5100 5-2017 (+a1)
5100 5-2017 (+a1)
5100 5-2017 (+a1)
AS 5100.5:2017
Bridge design
Part 5: Concrete
AP-G51.5-17
AS 5100.5:2017
(Incorporating Amendment No. 1)
This Australian Standard® was prepared by Committee BD-090, Bridge Design. It was
approved on behalf of the Council of Standards Australia on 17 March 2017.
This Standard was published on 31 March 2017.
Standards Australia wishes to acknowledge the participation of the expert individuals that
contributed to the development of this Standard through their representation on the
Committee and through the public comment period.
Standards may also be withdrawn. It is important that readers assure themselves they are
using a current Standard, which should include any amendments that may have been
published since the Standard was published.
Detailed information about Australian Standards, drafts, amendments and new projects can
be found by visiting www.standards.org.au
Australian Standard®
Bridge design
Part 5: Concrete
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Originated as HB 77.5—1996.
Revised and redesignated as AS 5100.5—2004.
Second edition 2017.
Reissued incorporating Amendment No. 1 (November 2018).
COPYRIGHT
© Standards Australia Limited
All rights are reserved. No part of this work may be reproduced or copied in any form or by
any means, electronic or mechanical, including photocopying, without the written
permission of the publisher, unless otherwise permitted under the Copyright Act 1968.
Published by SAI Global Limited under licence from Standards Australia Limited, GPO Box
476, Sydney, NSW 2001, Australia
ISBN 978 1 76035 718 4
AS 5100.5:2017 2
PREFACE
This Standard was prepared by Standards Australia Committee BD-090, Bridge Design, to
supersede AS 5100.5—2004.
This Standard incorporates Amendment No. 1 (November 2018). The changes required by
the Amendment are indicated in the text by a marginal bar and amendment number against
the clause, note, table, figure or part thereof affected.
This Standard is also designated as Austroads publication AP-G51.5-17.
The objectives of the AS(AS/NZS) 5100 series are to provide nationally acceptable
requirements for—
(a) the design of road, rail, pedestrian and cyclist path bridges;
(b) the specific application of concrete, steel and composite construction, which embody
principles that may be applied to other materials in association with relevant
Standards; and
(c) the assessment of the load capacity and rehabilitation of existing bridges.
These requirements are based on the principles of structural mechanics and knowledge of
material properties, for both the conceptual and detailed design, to achieve acceptable
probabilities that the bridge or associated structure being designed will not become unfit for
use during its design life.
The objective of this Part (AS 5100.5) is to specify requirements for the design and
construction of concrete bridges and associated structures.
Whereas earlier editions of the Bridge design series were essentially administered by the
infrastructure owners and applied to their own inventory, an increasing number of bridges
are being built under the design-construct-operate principle and being handed over to the
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relevant statutory authority after several years of operation. This Standard includes clauses
intended to facilitate the specification to the designer of the functional requirements of the
owner, to ensure the long-term performance and serviceability of the bridge and associated
structure.
Significant changes to the 2004 edition of AS 5100.5 are as follows:
(a) Increase in concrete strength specified in design rules from 65 MPa to 100 MPa. This
has resulted in the review of all equations in AS 5100.5 for strength and has meant, in
some instances, modification of equations such as the rectangular stress block model
and inclusion of requirements for confinement to the core of columns.
The application of the Standard is further influenced by the ductility class of the steel
reinforcement, with some new restrictions applying to the use of Ductility Class L
reinforcement. Ductility Class N stainless steel reinforcement may now be used.
(b) Section 2 ‘Design procedures actions and loads’, has been revised to align with the
AS/NZS 1170 series, Structural design actions, and additional design check methods
for designers to consider has been included.
(c) Section 3 ‘Design properties of materials’ has been reviewed to include—
(i) new shrinkage equations, to address autogenous and drying shrinkage; and
(ii) creep calculations, to modify the creep factor by revising the k2 and k3 factors,
including the addition of environmental and humidity factors.
(d) Specification of additional severe exposure classifications and requirements for
sulfate soils introduced in Section 4 on durability.
3 AS 5100.5:2017
(e) The fire resistance criteria in Section 5 ‘Design for fire resistance’ have been
updated.
(f) Section 6 ‘Methods of structural analysis’ has been completely revised.
(g) New Section 7 ‘Strut-and-tie modelling’, which provides rules on strut-and-tie
modelling, has been added.
(h) Clause 8.2 regarding design of flexural members for shear and torsion, incorporating
the modified compression field theory.
(i) Clause 10.7.3 regarding confinement to the core of columns in Section 10 has been
significantly changed due the importance of this issue for high strength concrete.
(j) Section 11 ‘Design of walls’ has been revised to be more consistent with Section 10
‘Design of columns for strength and serviceability’.
(k) Section 13 ‘Stress development, splicing of reinforcement and coupling of tendons’
has been completely revised.
(l) New Section 16 ‘Steel fibre reinforced concrete’ has been added.
NOTE: Traditionally, the terms ‘tie’ and ‘fitment’ were used interchangeably in this Standard.
The word ‘tie’ is now used only in the strut-and-tie analysis section while the term ‘fitment’ is
used for units such as stirrups and ligatures that perform various functions, such as restraining the
longitudinal reinforcement and resisting shear.
Statements expressed in mandatory terms in notes to tables are deemed to be requirements
of this Standard.
The terms ‘normative’ and ‘informative’ have been used in this Standard to define the
application of the appendix to which they apply. A ‘normative’ appendix is an integral part
of a Standard, whereas an ‘informative’ appendix is only for information and guidance.
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AS 5100.5:2017 4
CONTENTS
Page
Page
Page
Page
APPENDICES
A TESTING OF MEMBERS AND STRUCTURES.................................................... 202
B BEAM STABILITY DURING ERECTION ............................................................ 208
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STANDARDS AUSTRALIA
Australian Standard
Bridge design
Part 5: Concrete
1.1 SCOPE
This Standard sets out minimum requirements for the design and construction of concrete
bridges and associated structures that contain reinforcement or tendons, or both. It also sets
out minimum requirements for plain and steel fibre reinforced concrete (SFRC) members.
NOTES:
1 It is intended that the properties and requirements for reinforcement or tendons, as set out in
this Standard, may also be used for the design and construction of elements not containing
concrete, for example, stress laminated timber decks.
2 For design life of bridges covered by this Standard, see Clause 4.1.
1.2 APPLICATION
This Standard applies to structures and members in which the materials conform to the
following:
(a) Concrete with—
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AS
1379 Specification and supply of concrete
1478 Chemical admixtures for concrete, mortar and grout
1478.1 Part 1: Admixtures for concrete
3600 Concrete structures
3610 Formwork for concrete
3610.1 Part 1: Documentation and surface finish
3799 Liquid membrane-forming curing compounds for concrete
AS/NZS
1170 Structural design actions
1170.0 Part 0: General principles
1554 Structural steel welding
1554.3 Part 3: Welding of reinforcing steel
1554.6 Part 6: Welding stainless steels for structural purposes
1597 Precast reinforced concrete box culverts
1597.2 Part 2: Large culverts (exceeding 1200 mm span or 1200 mm height and up to
and including 4200 mm span and 4200 mm height)
1768 Lightning protection
2425 Bar chairs in reinforced concrete—Product requirements and test methods
3582 Supplementary cementitious materials and blended cement
3582.1 Part 1: Fly ash
3582.2 Part 2: Ground granulated blast-furnace
3582.3 Part 3: Amorphous silica
4671 Steel reinforcing materials
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EN
14889 Fibres for concrete
14889-1 Part 1: Steel fibres—Definitions, Specifications and Conformity
BS
6744 Stainless steel bars—Reinforcement of concrete—Requirements and test
methods
1.4 DEFINITIONS
1.4.1 General
For the purposes of this Standard, the definitions below apply.
1.4.2 Administrative definitions
1.4.2.1 Approved
Except as may be otherwise stated, approved by authority.
1.4.2.2 Authority
The body with jurisdiction over the provision of bridges and associated structures, and/or
responsible for the design, construction and maintenance of bridges within its jurisdiction.
1.4.2.3 Drawings
The drawings forming part of the documents setting out the work to be executed.
1.4.2.4 Specification
The specification forming part of the documents setting out the work to be executed.
1.4.3 Technical definitions
1.4.3.1 Action
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1.4.3.15 Cover
Distance between the outside of the reinforcing steel or tendons and the nearest permanent
surface of the member, excluding any applied surface finish.
1.4.3.16 Creep coefficient
Mean value of the ratio of creep strain to elastic strain under conditions of constant stress.
1.4.3.17 Critical shear perimeter
Perimeter defined by a line geometrically similar to the boundary of the effective area of a
support or concentrated load and located at a distance of d om/2 therefrom (see Figure 9.2.3).
1.4.3.18 Critical opening
Opening through the thickness of a slab where an edge, or part of the edge, of the opening
is located at a clear distance of less than 2.5b o from the critical shear perimeter [see
Figure 9.2.3(b)].
1.4.3.19 Design life
The period assumed in design for which a structure or a structural element required to
perform its intended purpose with minimal maintenance and without replacement or major
structural repairs.
1.4.3.20 Discontinuity
Abrupt change in geometry or loading, including prestress.
discipline; or
(b) if legislation is not applicable, a corporate member of the Institution of Engineers
Australia, or a person eligible to become a chartered professional engineer of the
Institution of Engineers, Australia, or the National Engineers Register in the relevant
discipline.
1.4.3.56 Reinforcement
Steel bar, wire or mesh but not tendons.
NOTE: Commonly referred to as reinforcing steel.
1.4.3.57 Self-compacting concrete
Concrete that is able to flow and consolidate under its own weight, completely fill the
formwork or excavation even in the presence of dense reinforcement, whilst maintaining
homogeneity and without the need for additional compaction, and which complies with
specified requirements for slump flow, viscosity and passing ability.
1.4.3.58 Shear wall
Wall that is intended to resist lateral forces acting in or parallel to the plane of the wall.
1.4.3.59 Short column
Column in which the additional bending moments due to slenderness can be taken as zero.
1.4.3.60 Slender column
Column that does not satisfy the requirements for a short column.
1.5 NOTATION
The symbols used in this Standard, including their definitions, are listed below.
Unless a contrary intention appears, the following applies:
(a) The symbols used in this Standard have the meanings ascribed to them below, with
respect to the structure, or member, or condition to which a clause is applied.
(b) Where non-dimensional ratios are involved, both the numerator and denominator are
expressed in identical units.
(c) The dimensional units for length, force and stress, in all expressions or equations, are
to be taken as millimetres (mm), newtons (N) and megapascals (MPa) respectively,
unless noted otherwise.
(d) An asterisk (*) placed after a symbol as a superscript (for example, M y* ) denotes a
design action effect due to the design load.
Symbol Definition
Ab cross-sectional area of a reinforcing bar
Ab.fit cross-sectional area of the fitment
Ac smallest cross-sectional area of the concrete strut at any point along its
length and measured normal to the line of action of the strut
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Symbol Definition
Ast cross-sectional area of longitudinal tensile reinforcement; or
cross-sectional area of reinforcement in the zone that would be in tension
under the design loads if the effects of prestress and axial loads are ignored
Ast.min minimum area of reinforcement required within the tensile zone (mm2).
NOTE: If Ast.min is zero only steel fibres are necessary to control cracking
Asv cross-sectional area of shear reinforcement
Asv.min cross-sectional area of minimum shear reinforcement
Asw cross-sectional area of the bar forming a closed fitment
Atr cross-sectional area of a transverse bar along the development length
Atr.min cross-sectional area of the minimum transverse reinforcement along the
development length
A1 a bearing area
A2 largest area of the supporting surface that is geometrically similar to and
concentric with A1
a a distance; or
horizontal projection of the inclined strut; or
perpendicular distance from the nearer support to the section under
consideration; or
dimension of the critical shear perimeter measured parallel to the direction of
bending being considered
asup length of a support in the direction of the span
av distance from the section at which shear is being considered to the face of the
nearest support
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Symbol Definition
D overall depth of a cross-section in the plane of bending; or
depth of member
Db overall depth of a spandrel beam
Dc depth of smaller column cross-sectional dimension if rectangular, or the
column diameter if circular
Ds overall depth of a slab or drop panel
d effective depth of a cross-section in the plane of bending
db nominal diameter of a bar, wire or tendon; or
nominal internal diameter of reinforcement bend or hook
dc width of the idealized strut; or
core dimension measured between the centre-lines of the outermost fitments
measured through the depth of the section
dd diameter of a prestressing duct
df diameter of the bar forming the tie; or
equivalent diameter of the steel fibre
dg maximum nominal aggregate size
do distance from the extreme compressive fibre of the concrete to the centroid
of the outermost layer of tensile reinforcement or tendons (not less than 0.8D
for prestressed concrete members)
dom mean value of do, averaged around the critical shear perimeter
dp distance from the extreme compressive fibre of the concrete to the centroid
of the tendons in the zone of the concrete in tension under ultimate strength
conditions
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Symbol Definition
eo vertical eccentricity between the centre of gravity of a beam and the
longitudinal axis through the lifting points
F force
FL peak load obtained from a 3-point notch bending test undertaken in
accordance with EN 14651
Ftd required tensile force in longitudinal reinforcement on the flexural tension
side of a member
fcm mean value of concrete compressive strength at the relevant age; or
mean concrete compressive strength at the time cracking is expected to occur
fcmi mean value of the in situ compressive strength of concrete at the relevant age
fcp mean compressive strength of concrete at transfer
fct uniaxial tensile strength of concrete
fct.f measured flexural tensile strength of concrete
fct.ef tensile strength of the concrete effective at the time when the cracks may
first be expected to occur
fct.sp measured splitting tensile strength of concrete
fcv concrete shear strength
fpb characteristic minimum breaking strength
fpy yield strength of tendons
fpo stress in prestressed reinforcement when stress in the surrounding concrete is
zero
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Symbol Definition
f cθ design characteristic compressive strength of concrete at elevated
temperature
f R,2 mean residual flexural strength determined at a crack mouth opening
displacement (CMOD) of 1.5 mm as determined from a 3-point notch
bending test undertaken in accordance with EN 14651
f R,4 mean residual flexural strength determined at a crack mouth opening
displacement (CMOD) of 3.5 mm as determined from a 3-point notch
bending test undertaken in accordance with EN 14651
f1.5 characteristic residual tensile strength of steel fibre reinforced concrete
(SFRC)
G permanent action (dead load)
gp permanent distributed load normal to the shear interface per unit length, in
newtons per millimetre
Hw floor-to-floor unsupported height of a wall
Hwe effective height of a wall
h overall depth of a joint
I second moment of area of the uncracked concrete cross-section about the
centroidal axis
Ic second moment of area of a concrete section
Icr second moment of area of a cracked section with the reinforcement
transformed to an equivalent area of concrete
Ief an effective second moment of area
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Symbol Definition
kR,4 ratio of the mean residual tensile strength taken at a crack opening
displacement (COD) of 1.5 mm
kr ratio of the dimension of an anchorage bearing plate to the corresponding
depth, or breadth, of the symmetrical prism
ku neutral axis parameter being the ratio, at ultimate strength under any
combination of bending and compression, of the depth to the neutral axis
from the extreme compressive fibre to d
kuo ratio, at ultimate strength, without axial force of the depth to the neutral axis
from the extreme compressive fibre to do
k1 a coefficient which allows for the effect of non-uniform self-equilibrating
stresses due to non-linear shrinkage or temperature profiles through the
member depth
k1 compressive strength factor for concrete at elevated temperatures
k2 tension reinforcement factor with strain 2%
k3 modulus of elasticity factor of steel reinforcement at elevated temperatures
k4 minimum tensile strength factor of tendons at elevated temperatures
k5 modulus of elasticity of tendons factor at elevated temperatures
L centre-to-centre distance between the supports of a flexural member
Le effective length of a column
Lef effective span of a member, taken as the lesser of ( Ln + D) and L for a beam
or slab; or
Ln + D/2 for a cantilever
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Symbol Definition
Lu unsupported length of a column, taken as the clear distance between the faces
of members capable of providing lateral support to the column. Where
column capitals or haunches are present, Lu is measured to the lowest
extremity of the capital or haunch
Lw overall length of a wall
lb length of the bursting zone
lf length of the steel fibre
M* design bending moment at a cross-section
M x* , M y* design bending moment in a column about the major and minor axes
respectively under the design axial force N*
M 1* , M 2* smaller and larger design bending moment respectively at the ends of a
column
Mc moment used in the calculation of the buckling load (Nc)
Mcr bending moment causing cracking of the section with due consideration to
prestress, restrained shrinkage and temperature stresses
Mg bending moment due to self-weight plus dynamic allowance at serviceability
limit state (SLS)
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N G* design axial force due to permanent effects at the ultimate limit state (ULS)
Symbol Definition
n number of bars uniformly spaced inside helical reinforcement; or
number of laterally restrained longitudinal bars; or
number of stress cycles
P force in the tendons; or
maximum force occurring at the anchorage during jacking; or
applied load
Pe total effective prestress force allowing for all losses
Pi prestressing force after initial losses
Pv vertical component of the prestressing force
p a reinforcement ratio
pc length of the outside perimeter of concrete cross-section
pcw web reinforcement ratio for compressive reinforcement
pw a reinforcement ratio in a wall; or
web reinforcement ratio for tensile reinforcement
R design relaxation of a tendon
Rb basic relaxation of a tendon
Rd design capacity of a member or structure (equal to Ru or sys. Ru.sys)
Ru ultimate strength of a member
Ru.sys mean capacity of the structure
r radius of gyration of a cross-section; or
radius of curvature of the duct; or
radius of curvature of the prestressing tendon
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Tb.cr bursting (or splitting) force across a strut caused at the time of cracking of
the strut
Symbol Definition
Tcr torsional cracking moment
Tu ultimate torsional strength
Tuc ultimate torsional strength of a beam without torsional reinforcement and in
the presence of shear
Tus ultimate torsional strength of a beam with torsional reinforcement
Tu.max ultimate torsional strength of a beam limited by web crushing failure
Tw vertical component of the force carried by the secondary struts
t time
tf thickness of topping or flange anchored by shear reinforcement
th hypothetical thickness of a member used in determining creep and shrinkage,
taken as 2Ag/ue
tw thickness of a wall
u effective length of the critical shear perimeter
ue exposed perimeter of a member cross-section plus half the perimeter of any
closed voids contained therein, used to calculate th
uh perimeter of the centre-line of the closed transverse torsion reinforcement
*
V design shear force at a cross-section
Vo shear force which would occur at a section when the bending moment at that
section was equal to the decompression moment Mo
Vt shear force, which, in combination with the prestressing force and other
action effects at the section, would produce a principal tensile stress of f ct at
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either the centroidal axis or the intersection of flange and web, whichever is
the more critical
Veq* equivalent factored shear force at any section for coexisting applied shear
(V*) and applied torsion (T*)
*
Vmin minimum design shear force for all load combinations
Symbol Definition
y larger overall dimension of a rectangular part of a cross-section
yt depth from the centroidal axis to the extreme fibre at the top of the section
y1 larger overall dimension of a closed fitment
Z section modulus of the uncracked cross-section, referred to the extreme fibre
at which flexural cracking occurs
z projection of the inclined compressive strut normal to the shear span; or
internal moment lever arm of the section
α coefficient; or
divergence angle between bottled shape compression fields and idealized
parallel sided strut
αb coefficient for beams
αc coefficient; or
modular ratio of the cast-in-place concrete to the precast beam concrete in
the composite member
αf stress range factor
αn coefficient
αs correlation factor
αtot sum in radians of the absolute values of successive angular deviations of the
prestressing tendon over a length of the tendon from the jacking end to a
point at distance (a) from that end (Lpa)
αv angle between the inclined shear reinforcement and the longitudinal tensile
reinforcement
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Symbol Definition
Δh lateral deviation of a slender beam at mid-span from the specified datum line
immediately after transfer
Δv lateral deflection caused by the self weight of the beam due to bending about
the y– y axis
ΔFcd required additional force in longitudinal reinforcement on the flexural
compression side of a member
Δσp change in the stress due to the change in length of the prestressed tie
δ, δb, δs moment magnifiers for slenderness effects
ε a strain
εcc strain due to concrete creep
εcs design shrinkage strain of concrete
cs* final design shrinkage strain of concrete
Symbol Definition
σci sustained stress in the concrete at the level of the centroid of the tendons,
calculated using the initial prestressing force prior to any time-dependent
losses and the sustained portions of all the service loads
σcp average intensity of effective prestress in concrete
σcp.f compressive stress due to prestress, at the extreme fibre where cracking
occurs
σcs maximum shrinkage-induced tensile stress on the uncracked section at the
extreme fibre at which cracking occurs
σ min minimum compressive stress at the extreme fibres under consideration, taken
as zero if tensile.
σ max maximum compressive stress at the extreme fibres under consideration.
σ max σ min maximum permissible stress range under fatigue loading for the calculated
σ min and equal to 0.45 f c when σmin is zero.
σo a constant sustained stress
σp effective stress in the prestressing tendon at the time under consideration
σpa stress in the tendon at a distance ‘a’, measured from the jacking end
σp.ef effective stress in the tendon after allowing for all losses
σpi stress in the tendon immediately after transfer
σpj maximum stress in the tendon at the jacking end
σpu maximum stress that would be reached in a tendon at ultimate strength of a
flexural member
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1.6 CONSTRUCTION
All concrete structures, designed in accordance with this Standard, shall be constructed so
that all the requirements of the design, as contained in the drawings and specifications, are
achieved.
1.8 DESIGN
1.8.1 Design data
In addition to the data specified in AS 5100.1, the drawings shall include the following
design data:
(a) Exposure classification for durability and associated cover to reinforcing steel and
tendons.
(b) Class and grade of concrete.
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(c) Grade, ductility class and type of reinforcement and grade and type of tendons.
(d) Reference number and date of issue of applicable design Standards.
(e) Design life (if not 100 years).
1.8.2 Design details
The drawings or specifications for concrete members and structures shall include, as
appropriate, the following:
(a) The shape and size of each member.
(b) The finish and method of control for unformed surfaces.
(c) Class of formwork for the surface finish specified.
(d) The number of bars, size, bar shape, spacing and location of all reinforcement to
AS 1100.501 and the required concrete cover.
(e) The size, quantity and location of tendons and structural fixings and the required
concrete cover.
(f) Any required properties of the concrete.
(g) The curing procedure.
(h) The force required in each tendon, the maximum jacking force to be applied in each
tendon and the order in which the tendons are to be stressed.
(i) The minimum strength concrete required before the application of prestressing forces.
(j) The location and details of planned construction and movement joints, and of
connections and splices.
(k) The minimum period of time before stripping of forms and removal of shores.
(l) Any constraint on construction assumed in the design including, where relevant, the
casting procedure.
(m) Any other requirements.
accordance with Clause 9.2. For slabs where the effective number of stress cycles is greater
than 2 000 000, the maximum calculated shear shall be limited to 0.54 times the value of
Vu. If the longitudinal tensile reinforcement ratio (Ast + Apt)/(bdo) is less than 0.01, the
permissible shear shall be reduced by multiplying the permissible value of Vu by the factor
[100(Ast + Apt)/(bdo)]1/3.
Where the potential failure surface could form a truncated cone or pyramid around a
support or loaded area, the maximum calculated shear shall be limited to 0.50 times the
value of Vuo specified in Clause 9.2.3.
2.2.5 Tensile stress range in steel
The maximum tensile stress range in tendons and reinforcement under the fatigue loading
specified in AS 5100.2 shall be limited to the appropriate values given in Table 2.2.5. These
stress ranges are applicable for 2 000 000 stress cycles.
To account for the design number of stress cycles (n), determined from AS 5100.2, the
values given in Table 2.2.5 shall be multiplied by the stress range factor αf—
where
αf = (2 106/n)1/3 . . . 2.2.5
0.74
In areas of high fluctuating stresses, such as in deck slabs, welded lap splices shall not be
used. All other welding, including tack-welding of reinforcing bar shall be in accordance
with AS/NZS 1554.3, or welded mesh in accordance with AS/NZS 4671, as appropriate.
The design for fatigue of welded reinforcement and welded mesh shall be in accordance
with recognised verification methods as approved by the relevant authority.
NOTE: Suitable verification methods for fatigue of welded reinforcement include:
(a) EN 1992-1-1
(b) EN 1992-2
(c) AASHTO LRFD
(d) FIB Model Code 2010
TABLE 2.2.5
PERMISSIBLE TENSILE FATIGUE
STRESS RANGES IN STEEL
Type of steel embedded in Fatigue design stress range
concrete limit, MPa
Reinforcement 150 (0.35 + 0.026d i /d b )
Prestressing wires and strands 150
in grouted plastic ducts
Prestressing wires, strands and 100
bars in grout steel ducts
Deflected pretensioned strands 70
and bent reinforcing bars
LEGEND:
d b = nominal diameter of a reinforcing bar
di = nominal internal diameter of reinforcement bend or
hook
stress variations in both the longitudinal reinforcement and tendons, and shear
reinforcement shall be calculated, assuming that all the shear force is carried by the
reinforcement and tendons. The angle between the compression struts and the longitudinal
axis of the member shall be chosen to be between 35° and 55°, except that for non-
prestressed slabs and trough girders the angle shall be between 40° and 55°.
TABLE 2.3.2
CAPACITY REDUCTION FACTORS (ϕ)
Type of action effect Capacity reduction factor (ϕ)
(a)
Axial force without bending:
(i) Tension: 0.8
(ii) Compression 0.6
(b) Bending without axial tension or compression: 0.6 (1.19 13k uo /12) 0.8
(c) Bending with axial tension: + [(0.8 ) (N u /N uot )] and
is obtained from Item (b)
(d) Bending with axial compression, where—
(i) N u N ub 0.6
(ii) N u < N ub 0.6 + [( 0.6) (1 N u /N uot )] and
is obtained from Item (b)
(e) Shear 0.7
(f) Torsion 0.7
(g) Bearing 0.6
(h) Bending, shear and compression in plain concrete 0.6
(i) Bending, shear and tension fixings 0.6
NOTE: Ductility Class L reinforcement shall only be used in accordance with Clause 1.2.
2.3.3 Strength check procedure for use with linear elastic stress analysis
The strength check procedure for use with a linear elastic stress analysis of a structure or
member shall be made as follows:
(a) The structure or member shall be analysed for the critical combination of factored
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TABLE 2.3.3
STRESS REDUCTION FACTORS FOR DESIGN
USING LINEAR STRESS ANALYSIS ( s)
Material Stress reduction factor
( s )
Concrete 0.6
Reinforcement and tendons 0.8
NOTE: Ductility Class L reinforcement shall only be used in
accordance with Clause 1.2.
Clause 7.3.3.
(f) The design strength of nodes shall be calculated in accordance with Clause 7.4.2 and
shall not be exceeded. The strength reduction factor (s) shall be in accordance with
Table 2.3.4.
TABLE 2.3.4
STRENGTH REDUCTION FACTORS FOR DESIGN
USING STRUT-AND-TIE ANALYSIS ( st)
Material Strength reduction factor ( st )
Concrete in compression 0.6
Steel in tension 0.8
2.3.5 Strength check procedure for use with non-linear analysis of framed structures
The strength check procedure for use with non-linear analysis of framed structures at
collapse shall be carried out as follows:
(a) It shall be confirmed that the design capacity of the structure (Rd) is equal to or
greater than the design action effect (Ed)—
Rd Ed . . . 2.3.5
(b) The design action effect (Ed) is the critical combination of factored actions as
specified in AS 5100.2 and Clause 2.5.
(c) The design capacity of the structure ( Rd = sys Ru.sys) shall be obtained using the
appropriate system strength reduction factor (sys ) given in Table 2.3.5, and the mean
capacity of the structure (Ru.sys) determined for the same combination of actions
adopted in Item (b) to evaluate Ed, by using non-linear frame analysis as specified in
Clause 6.5, with mean values of material properties.
TABLE 2.3.5
SYSTEM STRENGTH REDUCTION FACTORS FOR DESIGN USING NON-
LINEAR METHODS OF ANALYSIS ( sys )
System strength
Type of failure
reduction factor ( sys )
For structural systems in which the deflections and local deformations at high 0.7
overload are an order of magnitude greater than those for service conditions; and
yielding of the reinforcement and/or the tendon occurs well before the peak load
is reached
In all other cases 0.5 (see Note)
NOTE: Larger values than 0.5 may be used if it can be shown that, at high overload, adequate warning is given
of impending collapse.
2.3.6 Strength check procedure for use with non-linear stress analysis
The strength check procedure for use with non-linear stress analysis at collapse shall be
carried out as follows:
(a) It shall be confirmed that the design capacity of the structure or the component
member is equal to or greater than the design action effect—
Rd Ed . . . 2.3.6
where
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2.4.3 Cracking
2.4.3.1 General
Cracking in concrete structures shall be controlled by appropriate design, specification and
construction measures so that structural performance, durability and appearance of the
structure are appropriate to its intended use, which shall include cracking in both the pre-
hardened and hardened concrete states.
2.4.3.2 Control of cracking
The design requirements for the control of cracking in the hardened concrete state, as set
out in Clause 2.4.3.1, shall be deemed to be satisfied by designing the structure and
members to conform to the following requirements:
(a) Flexural cracking in concrete beams and slabs under service conditions shall be
controlled in accordance with Clause 8.6, 9.4.1, 9.4.2, 9.4.4 or 9.4.5, as appropriate.
(b) Cracking caused by shrinkage and temperature in concrete slabs shall be controlled in
accordance with Clause 9.4.3.
(c) Cracking in concrete walls under service conditions shall be controlled in accordance
with Clause 11.7.2.
(d) Cracking in D-regions under service conditions shall be controlled in accordance with
Clause 12.8.
(e) Early age thermal cracking of large and/or restrained members shall be controlled in
accordance with Clause 4.12.
Notwithstanding the above requirements, all concrete members shall be provided with a
minimum of reinforcement as follows:
(i) For members with a thickness of 150 mm or less, a single layer of reinforcement of
not less than 500 mm2/m shall be provided for each of two directions, at right angles
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to each other.
NOTE: Reinforcement provided for structural reasons may be considered as contributing
towards this requirement.
(ii) For members with a thickness greater than 150 mm, each face of the member shall be
reinforced with not less than 500 mm2/m for each of two directions at right angles to
each other. The layers shall be placed, as close to each surface as cover and detailing
permit.
NOTE: Reinforcement provided for structural reasons and located within 80 mm of the face
may be considered as contributing towards this requirement (see Tables 4.13.3.2 and
4.13.3.3).
Reinforcement shall be provided in two directions at right angles to each other and with a
spacing that is less than or equal to 300 mm.
Where considered necessary for durability requirements (for example, for exposure
classifications B2 or more severe) or where crack width is considered detrimental to the
appearance of the structure, consideration shall be given to limiting the steel stresses near
the tension face to values less than those given in this Standard. In addition, in such
conditions consideration shall be given to the detailing of the structure to minimize
cracking due to restraint and shrinkage.
2.4.4 Vibration
Vibration in concrete structures and members shall comply with the dynamic behaviour
requirements as specified in AS 5100.2 so that the serviceability and structural performance
are not adversely affected.
where the mean and upper characteristic values are obtained by multiplying these values by
1.4 and 1.8, respectively.
3.1.1.4 Supplementary cementitious materials
3.1.1.4.1 General
Values of fct.ef shall be obtained from 0.6 f cm but not less than 3.0 MPa and fcm is the mean
concrete compressive strength at the time cracking is expected to occur.
(b) For Standard strength grades at 28 days determined from Table 3.1.2 and determined
by test in accordance with AS 1012.17.
NOTES:
1 Where Ecj is determined from Item (a) or (b) above, consideration should be given to the fact
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TABLE 3.1.2
CONCRETE PROPERTIES AT 28 DAYS
f c , MPa 20 25 32 40 50 65 80 100
f cmi , MPa 22 28 35 43 53 68 82 99
E c , MPa 24 000 26 700 30 100 32 800 34 800 37 400 39 600 42 200
3.1.3 Density
The density of concrete (ρ) shall be either—
(a) taken as not less than 2400 kg/m3 for normal weight concrete; or
(b) determined by test in accordance with AS 1012.12.1 or AS 1012.12.2.
3.1.4 Stress-strain curves
The stress-strain curve for concrete shall be either—
(a) assumed to be of curvilinear form defined by recognized simplified equations; or
(b) determined from suitable test data.
For design purposes, the shape of the in situ uniaxial compressive stress-strain curve shall
be modified so that the maximum stress is 0.9 f c .
The maximum stress specified above shall not apply when assessing the flexural strength of
plastic hinge zones of bridge columns in accordance with Clause 10.2.4.2.
3.1.5 Poisson’s ratio
Poisson’s ratio for concrete (v) shall be either—
(a) taken as equal to 0.2; or
(b) determined by test in accordance with AS 1012.17.
3.1.6 Coefficient of thermal expansion
The coefficient of thermal expansion of concrete shall be either—
(a) taken as equal to 10 106/°C, consideration being given to the fact that this value
has a range of 20%; or
(b) determined from suitable test data.
3.1.7 Shrinkage
3.1.7.1 Calculation of design shrinkage strain
The design shrinkage strain of concrete (εcs) shall be determined—
(a) from measurements on similar local concrete;
(b) by tests after eight weeks of drying, in accordance with AS 1012.13 and modified for
the appropriate age; or
(c) by calculation in accordance with Clause 3.1.7.2.
3.1.7.2 Design shrinkage strain
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When the design shrinkage strain of concrete (εcs) is to be calculated, it shall be determined
as the sum of the chemical (autogenous) shrinkage strain (ε cse) and the drying shrinkage
strain (εcsd), as follows:
εcs = εcse + εcsd . . . 3.1.7.2(1)
The autogenous shrinkage strain shall be taken as—
cse cse
*
1.0 e 0.1t . . . 3.1.7.2(2)
where t is the time (in days) after setting and cse
*
is the final autogenous shrinkage strain
given by—
cse
*
0.06 f c 1.0 50 10 6 . . . 3.1.7.2(3)
At any time (t), in days, after the commencement of drying, the drying shrinkage strain
shall be taken as—
csd k1k 4 csd.b . . . 3.1.7.2(4)
and k1 is obtained from Figure 3.1.7.2 and k4 is equal to 0.7 for an arid environment, 0.65
for an interior environment, 0.6 for a temperate inland environment and 0.5 for a tropical or
near-coastal environment.
The basic drying shrinkage strain ( csd.b ) shall be taken as—
csd.b 1.0 0.008 f c csd.b
*
. . . 3.1.7.2(5)
where the final drying basic shrinkage strain ( csd.b
*
) depends on the quality of the local
aggregates, which shall be taken as 800 10 for Sydney and Brisbane, 900 106 for
6
NOTES:
1 Based on a value of csd.b
*
= 1000 10 6 this method gives the typical design shrinkage strains
after 30 years shown in Table 3.1.7.2.
Consideration should be given to the fact that ε cs has a range of 30%.
2 Concrete exposed to early drying undergoes shrinkage due to capillary suction. This can
result in cracking and poor service performance, particularly of exposed slabs. The amount of
shrinkage from suction depends on the ambient conditions and the concrete mix, and can
exceed the combined shrinkage from other causes. Therefore, it is important to prevent
excessive drying of concrete between the commencement of casting and the application of
curing at the completion of finishing.
1.8
th = 50 mm
1.6
α 1t 0 . 8
k1 = t h = 10 0 m m
t 0 . 8 + 0.15 t h
1.4
α 1 = 0.8 + 1. 2e - 0 .0 0 5 t h
t h = 20 0 m m
1. 2
W h ere t i s in d ays
1.0
k1 th = 400 mm
0.8
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0.6
0.4
0. 2
0
1 3 10 30 10 0 1 3 10 30
DAYS YE ARS
TIM E SIN CE CO M M EN CEM ENT OF DRYIN G, t
TABLE 3.1.7.2
TYPICAL DESIGN SHRINKAGE STRAINS AFTER 30 YEARS ( csd.b
*
1000 )
*
Design shrinkage strain cs 10 6
Tropical, near coastal
Temperate inland
f c Arid environment Interior environment and coastal
environment
MPa environment
t h , mm t h , mm t h , mm t h , mm
50 100 200 400 50 100 200 400 50 100 200 400 50 100 200 400
25 990 870 710 550 920 810 660 510 850 750 610 470 720 630 510 400
32 950 840 680 530 880 780 640 500 820 720 590 460 690 610 500 390
40 890 790 650 510 830 740 610 480 780 690 570 450 660 590 490 390
50 830 740 610 490 770 690 580 460 720 650 540 440 620 550 470 380
65 730 650 560 460 680 620 530 440 640 580 500 410 560 510 440 370
80 630 570 500 420 590 540 480 410 560 520 450 390 500 460 410 360
100 490 460 420 380 480 450 410 370 460 430 400 360 420 400 370 340
3.1.8 Creep
3.1.8.1 General
The creep strain at any time (t) caused by a constant sustained stress (σo) shall be calculated
from the following equation:
εcc = φcc σo/Ec . . . 3.1.8.1
where
Ec = mean value of the modulus of elasticity of the concrete at 28 days
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TABLE 3.1.8.2
BASIC CREEP COEFFICENT
Characteristic strength ( f c ), MPa 20 25 32 40 50 65 80 100
Basic creep coefficient (φ cc.b) 5.2 4.2 3.4 2.8 2.4 2.0 1.7 1.5
In the absence of more accurate methods, φcc at any time (t) shall be taken as—
φcc = k2 k3 k4 k5 φcc.b . . . 3.1.8.3
where k2 is obtained from Figure 3.1.8.3 and k3 depends on the age of the concrete ( ) at the
time of loading (in days) and is given by the following:
k3 = 2.7/[1+log()] for 1 day
k4 = 0.7 for an arid environment, 0.65 for an interior environment, 0.60 for a
temperate inland environment and 0.50 for a tropical or near-coastal
environment
k5 = a modification factor for high strength concrete, which shall be taken as—
k5 = 1.0 when f c 50 MPa; or
1.8
th = 50 mm
1.6
α 2t 0.8
k2 = t h = 10 0 m m
t 0.8 + 0.15 t h
1.4
α 2 = 0.8 + 1.12e - 0 .0 0 5 t h
t h = 20 0 m m
1. 2
W h ere t i s in d ays
th = 400 mm
1.0
k2
0.8
0.6
0.4
0. 2
0
1 3 10 30 10 0 1 3 10 30
DAYS YE ARS
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TABLE 3.1.8.3
FINAL DESIGN CREEP COEFFICIENTS ( cc* ) FOR CONCRETE FIRST LOADED
AT 28 DAYS
*
cc
The ductility of the reinforcement shall be characterized by its uniform strain (εsu) and
tensile strength to yield stress ratio and designated as low (L) or normal (N) Ductility Class
as given in Table 3.2.1. For the purposes of design, values of these parameters for each
Ductility Class shall comply with AS/NZS 4671, and for stainless steel with BS 6744.
The physical and mechanical properties of stainless steel reinforcement shall be in
accordance with BS 6744 and the chemical composition conform to one of designations
1.4301, 1.4162, 1.4436, 1.4429, 1.4362 or 1.4462 to EN 10088-1 (as identified by
BS 6744).
Ductility Class L reinforcement may be prequalified and reclassified as Ductility Class LP
and used as shear and torsion reinforcement to Clauses 8.2.5 or longitudinal shear
reinforcement to Clause 8.4 provided the following requirements are satisfied:
(a) A minimum uniform strain of 0.025.
(b) A minimum tensile strength to yield stress ratio of 1.05.
Testing to determine Items (a) and (b) shall be undertaken in accordance with the
following:
(i) For individual fitments, 3 tests per coil or per 5 tonnes, whichever is the greater.
(ii) For transverse bars of welded mesh, 3 tests per coil or per 5 tonnes, whichever is the
greater.
(iii) For longitudinal bars of welded mesh, 1 test per coil or per 5 tonnes, whichever is the
greater.
The minimum values of uniform strain for Ductility Class LP reinforcement are not lower-
characteristic values, but are lower limits placed on every tensile test result. The uniform
strain in any test shall be not less than 0.025, and the tensile strength to yield stress ratio
shall be not less than 1.05.
NOTE: In AS/NZS 4671, ε su is referred to as Agt, expressed as a percentage, and fsy is referred to
as Re .
TABLE 3.2.1
YIELD STRENGTH AND DUCTILITY CLASS OF REINFORCEMENT
Reinforcement Characteristic Uniform
Ductility
yield strength (f sy ) strain
Type Designation grade class
MPa (ε su )
Bar plain to AS/NZS 4671 R250N 250 0.05 N
Bar plain deformed or indented to D500L 500 0.015 L
AS/NZS 4671 D500N 500 0.05 E
D500E 500 0.10
Bar deformed to Clause 3.2.1 D500LP 500 0.0253 LP
Welded mesh, plain, deformed or R500L, D500L, I500L 500 0.015 L
indented to AS/NZS 4671
R500N, D500N, 500 0.05 N
I500N
Welded mesh, plain, deformed or R500LP, D500LP, 500 0.0253 LP
indented to Clause 3.2.1 I500LP
Stainless steel plain bar to BS 6744 200 200 0.05 N
(see Note 2)
Stainless steel ribbed bar to 500 650 0.05 N
BS 6744 (see Note 2)
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NOTES:
1 Reference should be made to AS/NZS 4671 for explanation to designations applying to 500 MPa steels
and BS 6744 for stainless steels.
2 Stainless steel bars to BS 6744 are deemed to satisfy the requirements for Ductility Class N reinforcement
as in AS/NZS 4671.
3 Ductility Class LP is Ductility Class L reinforcement that is prequalified to meet the requirements of
Clause 3.2.1, that is minimum uniform strain of 0.025 and minimum tensile strength to yield stress ratio of
1.05.
TABLE 3.3.1
TENSILE STRENGTH OF COMMONLY USED WIRE STRAND AND BAR
Characteristic Characteristic
Nominal
Material type and Area minimum breaking minimum breaking
diameter
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following equation:
R = k6 k7 k8 Rb . . . 3.3.4.3
where
k6 = a coefficient, dependent on the duration of the prestressing force
= log [5.4(j)1/6]
j = time after prestressing, in days
k7 = a coefficient, dependent on the stress in the tendon as a proportion of fpb,
determined from Figure 3.3.4.3
k8 = a coefficient, dependent on the average annual temperature (T) in degrees
Celsius, taken as T/20 but not less than 1.0
Rb = basic relaxation of a tendon after one thousand hours at 20°C, as specified in
Clause 3.3.4.2
3.3.4.4 Design relaxation for elevated temperature curing
Where curing of a prestressed member is carried out at elevated temperatures, ultimate
relaxation shall be deemed to have occurred during the curing cycle. In such cases, the
design relaxation shall be taken as either—
(a) the value determined from suitable test data; or
(b) for low relaxation strand stressed to 0.8fp, a value of 7% to 10%.
COEFFICIENT k 7
A llll oy sste
te e l b
bar
ar
W ire an d str an d
0
0.4 0. 5 0.6 0.7 0.8
STRESS IN TEN D O N AS PRO PORTIO N O F f p b
The immediate loss of prestress shall be estimated by adding the calculated losses of
prestress due to elastic deformation of concrete, friction, anchoring and other immediate
losses as are applicable.
3.4.2.2 Loss of prestress due to curing conditions
Where curing of a prestressed member is carried out at ambient conditions, the design
relaxation shall be as determined by Clause 3.3.4.3.
Where curing of a prestressed member is carried out at elevated temperature (such as steam
curing), the design relaxation shall be determined from Clause 3.3.4.4 and shall be
considered as an immediate loss.
3.4.2.3 Loss of prestress due to elastic deformation of concrete
Calculation of the immediate loss of prestress due to elastic deformation of the concrete at
transfer shall be based on the value of modulus of elasticity of the concrete at that age. For
multi-stage prestressing, elastic deformation losses resulting from each stage of stressing
shall be determined.
3.4.2.4 Loss of prestress due to friction
The stress variation along the design profile of a tendon due to friction in the jack, the
anchorage and the duct shall be assessed in order to obtain an estimate of the prestressing
forces at the critical sections considered in the design.
The extension of the tendon shall be calculated allowing for the variation in tension along
its length, as follows:
(a) Friction in the jack and anchorage The loss of prestress due to friction in the jack
and anchorage shall be determined for the type of jack and anchorage system to be
used.
(b) Friction along the tendon Friction loss shall be calculated from an analysis of the
forces exerted by the tendon on the duct. In the absence of more detailed calculations,
the stress in the tendon at a distance (a) measured from the jacking end (σpa) shall be
taken as—
pa pje
p Lpa
tot
. . . 3.4.2.4
where
σpj = maximum stress in the tendon at the jacking end
e = base of Napierian logarithms
μ = friction curvature coefficient for different conditions
In the absence of specific data and when all tendons in contact in the
one duct are stressed simultaneously, μ shall be taken as—
(i) for greased-and-wrapped coating, 0.15;
(ii) for bright and zinc-coated metal sheathing, 0.15 to 0.20;
(iii) for bright and zinc-coated flat metal ducts, 0.20; and
(iv) for polyethylene ducts, 0.14.
αtot = sum in radians of the absolute values of successive angular deviations of
the prestressing tendon over a length of the tendon from the jacking end
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Where reinforcement is distributed throughout the member so that its effect on shrinkage is
mainly axial, the loss of prestress in the tendons may be taken as—
E p cs
. . . 3.4.3.2
1 15 As / Ag
4.1 GENERAL
The requirements of this Section apply to plain, steel fibre reinforced, and steel reinforced
and prestressed concrete structures and members with a design life of 100 years in
accordance with AS 5100.1.
For structures with design life of 50 (20%) years, the durability requirements of AS 3600
may be adopted.
NOTES:
1 More stringent requirements may be appropriate for structures with a design life in excess of
100 years (for example, monumental structures or high risk significant structures crossing
major waterways), while some relaxation of the requirements may be acceptable for structures
with a design or service life of less than 40 years (for example, temporary structures).
2 Durability is a complex topic and compliance with these requirements may not be sufficient
to ensure a durable structure.
3 Design life is defined in Clause 1.4.3.19 and is the period assumed in design for which a
structure or structural element is required to perform its intended purpose with minor
maintenance and without replacement or major structural repairs.
TABLE 4.3
EXPOSURE CLASSIFICATIONS
Exposure classification
reinforced or prestressed
Surface and exposure environment
concrete members
(see Notes 1 and 13)
1 Surface of members in contact with the ground (see Notes 2 and 3):
(a) Members protected by a damp-proof membrane in non-aggressive A
soils
(b) Members in non-aggressive soils (see Note 4) B1
(c) Members in aggressive soils:
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be adequate for sodium sulfate conditions. For the magnesium sulfate conditions, specific consideration
should be given to concrete containing not only supplementary cementitious materials but also other
protective measures that are likely to resist this type of sulfate.
7 The climatic zones referred to are those given in Figure 4.3, which is based on the Bureau of Meteorology
map, Major seasonal rainfall zones of Australia, Commonwealth of Australia, 2005.
8 Industrial refers to areas that are within 3 km of industries that discharge atmospheric pollutants.
9 For the purpose of this Table, the coastal zone includes locations within 1 km of the shoreline of large
expanses of saltwater. Where there are strong prevailing winds or vigorous surf, the distance should be
increased beyond 1 km and higher levels of protection should be considered.
10 The spray zone is the zone from 1 m above wave crest level.
11 The tidal/splash zone is immediately below the spray zone and includes the zone 1 m below lowest
astronomical tide (LAT) and up to 1 m above highest astronomical tide (HAT) on vertical structures, and all
exposed soffits of horizontal structures over the sea.
12 Further guidance on measures appropriate in exposure classification U may be obtained from AS 3735 and
AS 3735 Supp l respectively which cover exposure classifications and aggressiveness of various liquids and
ground environments in contact with a concrete surface.
13 In this Table, classifications A, B1, B2, C1 and C2 represent increasing degrees of severity of exposure,
while classification U represents an exposure environment not specified in this Table but for which a
degree of severity of exposure should be appropriately assessed. Protective surface coatings may be taken
into account in the assessment of the exposure classification.
14 The interior of a box girder or voided member is typically determined to be a classification A, unless a
more detailed assessment is carried out identifying a different exposure classification. Where the exterior of
a box girder or voided member is exposed to a salt spray, the interior should be at least a classification B1.
This Note does not apply to the internal surfaces of the segmental box girders.
13 0 ° 14 0 °
C L AS S I FI CAT I O N 15 0 °
10 ° T h u r s d ay I s
T R O PI CA L 10 °
Yirrkala
Ashmore Is DA RW I N We i p a
T E M PER AT E
Tr o u g h t o n I s Katherine
ARID
Wyndham Cook town
Cairns Willis Is
D e r by
TROPICAL Normanton
Broome Halls Creek
To w n s v i l l e
Camooweal
Te n n a n t C r e e k
Pt Hedland Mt Isa
Hughenden 20°
20° M a c k ay
North West
Cape Wittenoom
Alice Springs Longreach
Rockhampton
Mundiwindi
Giles Bundaberg
ARID Birdsville Ta r o o m
C a r n a r vo n
C h a r l ev i l l e
Meekatharra Wiluna Oodnadatta
BRISBANE
L ave r t o n Marree
Moree
Geraldton Grafton
Fo r r e s t Cook Ta r c o o l a B o u r ke
Kalgoorlie
30°
Eu c l a Cobar Ta m w o r t h
30° Ceduna Po r t A u g u s t a
Dubbo
PER T H TEMPER ATE TEMPER ATE Newcastle
Wa g i n Mildura
Esperance SY D N E Y
ADEL AIDE
CA N B ER R A Wo l l o n g o n g
Cape Leeuwin
A l b a ny Horsham Ec h u c a
Kangaroo Is.
Cooma
MELBOURNE
Po r t l a n d Sale
CLIMATIC ZO NES
AUSTR ALIA Currie Burnie
40°
Launceston
40° Queenstown
Kilometres 200 0 200 400 600 800 Kilometres
PR O J EC T I O N A L B ER S C O N I CA L EQ UA L A R E A Hobar t
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110 ° 12 0 ° 13 0 ° 14 0 ° 15 0 °
An alternative concrete mix for durability may be used if approved by the authority. The
concrete mix and associated testing shall demonstrate that the concrete can provide a level
of durability at least equal to that provided by this Standard for the concrete structure over
its required design life.
Where self-compacting concrete (SCC) as defined in Clause 1.4.3.57 is used, it shall also
comply with the required properties specified in Table 4.4.1(C) for slump flow, T500 time
and passing ability as determined by test method AS 1012.3.5.
TABLE 4.4.1(A)
MINIMUM STRENGTH AND CEMENT MATERIAL CONTENT,
MAXIMUM WATER/CEMENT (W/C) MATERIAL RATIO
AND CURING REQUIREMENTS FOR CONCRETE
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6
Minimum
average
compressive
strength at the
Minimum Minimum
completion of
Maximum water/ initial curing
Exposure Minimum cement accelerated
cement material requirement
classification f c material curing and/or at
(W/C) ratio (see
content the time of
Clause 17.3.5.1)
stripping of
forms or
removal from
moulds
at least 3 days
B1 32 330 0.50 Cure 20
continuously for
B2 40 400 0.45 at least 7 days 25
NOTE: For acidic and sulfate deterioration mechanisms in exposure classifications C1 and C2, a water
cementitous material (w/c) ratio of less than or equal to 0.4 and with a limit for the minimum cement material
content of 420 kg/m3 may be used.
TABLE 4.4.1(B)
COMPLIANT CEMENT MATERIAL PROPORTIONS (MINIMUM TO MAXIMUM
RANGE)
Proportioning of cement material
Exposure (% mass) in concrete mixes
classification Fly ash Amorphous silica
Slag Triple blends
(FA) (SF)
Up to 60 * /up to 40 ‡ , up to
A 100 * /0 to 70 * /30 † 100 * /0 to 60 * /40 ‡ 100 * /0 to 90 * /10 §
25 † , up to 10 §
Up to 60 * /up to 40 ‡ , up to
B1 100 * /0 to 70 * /30 † 100 * /0 to 60 * /40 ‡ 100 * /0 to 90 * /10 §
25 † , up to 10 §
70 * /30 ‡ to Up to 60 * /up to 40 ‡ , up to
B2 80 * /20 † to 70 * /30 † 92 * /8 § to 90 * /10 §
60 * /40 ‡ 25 † , up to 10 §
C1 75 * /25 † to 60 * /40 † 50 * /50 ‡ to 92 * /8 § to 90 * /10 § 25 * 30 * /60 ‡ 67 ‡ /8 § 10 §
30 * /70 ‡ 70 * 75 * /17† 20† /8 § 10 §
C2 75 * /25 † to 60 * /40 † 50 * /50 ‡ to 92 * /8 § to 90 * /10 § 25 * 30 * /60 ‡ 67 ‡ /8 § 10 §
30 * /70 ‡ 70 * 75 * /17† 20† /8 § 10 §
* % of GP (general purpose Portland cement to AS 3972)
† % of FA
‡ % of slag
§ % of SF
NOTES:
1 The Table is by percent (%) of total combined cement (by weight).
2 Where proportioning of cement material in concrete mixes utilizes replacement levels of supplementary
cementitious materials outside of these limits, a more detailed methodology may be mandated by the
authority, addressing potential lower early strength development, curing and stripping times and concrete
strength requirements for early lifting.
3 The cement material proportions in this Table are based on the replacement of type GP cement with a
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supplementary cementitious material. The use of special purpose cement as defined in AS 3972 on its own
may be considered for particular applications if approved by the relevant authority.
4 Where a member is located in more than one exposure environment, the concrete mix shall either comply
with the relevant mix requirements for each environment, or the mix requirements for the more severe
environment may apply to the whole member, provided the additional cover for the more severe
environment is demonstrated to provide equivalent durability for the mix in then less severe environment.
TABLE 4.4.1(C)
REQUIRED PROPERTIES OF SELF COMPACTING CONCRETE (SCC)
Properties of SCC Measurement Observations
Slump flow 550–750 mm spread The aggregate shall be evenly distributed
throughout the concrete paste within the spread
and shall not exhibit signs of segregation
T 500 time Achieve a spread of 500 mm The final spread shall not exceed 750 mm in
(measure of viscosity) within 2 to 5 seconds diameter
Passing ability 10 mm The concrete shall not exhibit signs of
segregation
4.4.2 Curing
4.4.2.1 General
Concrete shall be cured, using one or a combination of the methods set out in
Clauses 4.4.2.2 to 4.4.2.6 and as stated in Table 4.4.
The concrete shall be protected from moisture loss until the commencement of the curing.
Curing shall not be interrupted for more than half an hour when a combination of curing
methods is used.
For accelerated curing methods, the concrete strength for checking the adequacy of curing
shall be determined by test specimens cured with and in the same manner as the concrete
member.
4.4.2.2 Moist curing
Concrete shall be kept continuously moist and the concrete maintained at a temperature
above 5°C.
4.4.2.3 Membrane curing
Where curing compounds are permitted by the authority, they shall be correctly applied to
all exposed concrete surfaces. The concrete shall be maintained at a temperature above 5°C.
Curing compounds shall not be used on concrete surfaces of structures in seawater or
brackish water.
4.4.2.4 Polyethylene sheet
Polyethylene sheet may be used, provided its application ensures effective sealing.
4.4.2.5 Retaining formwork in place
Where formwork is left in place to satisfy formwork removal times, either as stated in the
relevant Standard or as required by the authority, or where formwork is left in place for
curing purposes, any exposed surfaces of the concrete shall be cured by other means in
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4.6 ABRASION
In addition to the other durability requirements of this Section, concrete for members
subject to abrasion from traffic shall have a characteristic compressive strength not less
than the applicable value given in Table 4.6.
TABLE 4.6
STRENGTH REQUIREMENTS FOR ABRASION
Minimum
characteristic
Member type and/or traffic condition compressive strength
( f c )
MPa
Footpaths and cyclist paths 25
Combined pedestrian pavements and cyclist paths, subject to 32
occasional pneumatic tyre traffic
Pavement and bridge decks subject to the following:
(a) Pneumatic tyre traffic 40
(b) Non-pneumatic tyre traffic (excluding studded tyres) 50
(c) Studded tyres To be assessed
but not less than 50
NOTE: f c refers to the characteristic compressive strength of the required member subject
to abrasion.
TABLE 4.8
EXPOSURE CLASSIFICATION FOR CONCRETE IN SULFATE, ACIDIC
AND SALINE SOILS
Exposure conditions * Exposure classification
Sulfates (expressed as SO 4 ) † Chlorides in Soil
Soil conditions
In soil ** In groundwater pH groundwater conditions
A‡
ppm ppm ppm B§
* Acid sulfate soils or sulfate soils with a magnesium ions content of less than 1000 mg/l.
† Approximately 100 ppm SO 4 = 80 ppm SO 3
‡ Soil conditions A—high permeability soils (for example, sands and gravels) that are in groundwater
§ Soil conditions B—low permeability soils (for example, silts and clays) or all soils above groundwater
** 1 ppm is equivalent to 1 mg of sulfate to 1 kg of dried soil.
NOTES:
1 This is a simplified approach to the complex response of concrete to a range of aggressive soil
conditions. It is common to find more than one chemical in the service environment and the effect of
these chemicals may be modified in the presence of others. For example, sulfate ions become
aggressive at levels of 600 to 1000 ppm when combined with magnesium or ammonium ions. In the
presence of chloride ions, however, attack by sulfate ions generally exhibits little disruptive expansion
with the exception of conditions of wetting and extreme drying where crystallization can cause surface
fretting of concrete.
2 If magnesium ions exceed 1000 mg/l together with sulfate ions (SO 4 ) more than 1000 ppm in soil or
400 ppm in ground water, an aggressivity or exposure classification of one higher class should be
adopted, additional protective measures should be considered and expert advice should be sought.
3 Corrosion damage by chlorides is only relevant to the steel reinforcement and steel inclusions in
concrete and not to steel fibres. If there is no reinforcement or the reinforcement is otherwise
adequately protected (for example, by a coating or cathodic protection), the chloride content is not
relevant to the exposure classification.
4 Chemical concentrations relate only to the proportion of chemical present that is water soluble.
5 Acidic ground conditions can be caused by dissolved ‘aggressive’ carbon dioxide, pure and very soft
waters, organic and mineral acids, and bacterial activity. Care is required in the assessment of pH
under concrete element installation and lifetime conditions since pH can change over the lifetime of the
concrete element. Therefore, the pH should not be assessed only on the basis of a present-day test
result, rather the ground chemistry should be considered over the design life of the concrete element.
Testing for pH should be carried out either in situ or immediately after sampling as there is otherwise a
risk of oxidation with time, leading to apparent acidity, which does not correctly represent in situ
conditions.
6 pH alone may be a misleading measure of aggressivity without a full analysis of causes (for example,
still vs running water).
7 Contamination by the tipping of mineral and domestic wastes or by spillage from mining, processing or
manufacturing industries presents special durability risks due to the presence of certain aggressive
acids, salts and solvents, which can either chemically attack concrete or lead to a corrosion risk.
Certain ground conditions cannot be properly addressed by reference only to Table 4.8. These
conditions include, for example, areas where acid-sulfate soils exist, contamination by industrial and
domestic waste, or spillage from mining, processing or manufacturing industries. This presents special
durability risks due to the presence of certain aggressive acids, alkalis, salts and solvents that can lead
to either chemical attack of concrete or lead to a corrosion risk. In the absence of site-specific chemical
information, the exposure condition should be assessed as ‘exposure classification C1’ for domestic
refuse and ‘exposure classification C2’ for industrial/mining waste tips. Chemical analysis of the latter
may allow a lower risk classification.
8 For piles and other concrete elements in disturbed soil where accelerated corrosion may occur, the
exposure classification shall be for soil conditions A in the above Table.
9 Attention is drawn to regions of dry land salinity where the chloride concentrations in the soil can be
greater than seawater (for example, Murray River basin). This can affect the upper few metres of a
concrete element where the aggressive salts accumulate.
10 Cathodic protection should not fall below the levels recommended in AS 2832.5.
11 Testing for pH shall be in accordance with AS 1289.4.3.1. Testing for sulfate shall be in accordance
with BS 1377.
(b) Curing Further to the requirements of this Section, the period of continuous curing
for all cast-in-place concrete shall be not less than 14 days.
Curing compounds shall not be used on structures within tidal and splash zones of a
marine environment.
(c) Electrical continuity of the steel reinforcement Steel reinforcement shall be made
electrically continuous in concrete members, including piles, below 1 m above the
highest astronomical tide to allow for future application of a cathodic protection
system.
(d) Application of protective coatings Where required by the authority, a protective
coating against chloride ingress shall be applied to exposed concrete surfaces
subjected to an exposure classification C2 environment.
NOTE: Concrete surfaces exposed to an exposure classification C1 environment may also
require additional protection.
(e) Reinforcement Steel reinforcement shall be supported by premium grade extruded
fibre concrete supports and spacers manufactured under factory-controlled conditions
and of material compatible with the surrounding concrete.
NOTE: Other measures that may be considered to enhance concrete durability include the use
of controlled permeability formwork, use of stainless steel reinforcement in high exposure
locations, the addition of corrosion-inhibiting admixtures in the concrete and the installation
and maintenance of a cathodic protection system.
TABLE 4.10
SUPPLEMENTARY CEMENTITIOUS MATERIAL LIMITS IN THE CONCRETE
MIX TO MITIGATE ALKALI AGGREGATE REACTIVITY (AAR)
Proportion of supplementary cementitious material
Supplementary cementitious material
%
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Fly ash 20 to 30
Slag 50 to 70
Amorphous silica 8 to 10
NOTE: The table is by percent of total combined weight (Portland cement portion not shown).
NOTE: Thermocouples should be located within the concrete member being constructed to
monitor the maximum temperature and differential temperature across the concrete. Typical large
and restrained members include crossheads, diaphragms, columns, abutments, footings and pile
caps.
TABLE 4.13.1
MAXIMUM VALUES OF ACID-SOLUBLE CHLORIDE AND SULFATE ION
CONTENT IN CONCRETE AS CAST
Mass of maximum acid soluble Mass of maximum acid-soluble
Form of construction chloride ion content, sulfate ion content, % by mass of
kg/m 3 of concrete cement material
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2 Due to the significant differences between the physical properties of epoxy resin and epoxy
materials and concrete, they do not act monolithically under physically or chemically applied
loadings, and may result in the failure of the seal. In particular, differences in the coefficient
of thermal expansion may result in excessive stresses at the bond interface. This could
eventually result in failure at the interface or within the concrete substrate (lower strength),
unless a balance is achieved between the sizes of the cross-sectional area of the repair and the
bond area required at the interface, to sustain the stresses generated.
In the determination of an appropriate cover, consideration shall be given to—
(i) the size and shape of the member;
(ii) the size, type and configuration of the reinforcement and, if present, the tendons or
ducts; and
(iii) the aggregate size, the workability of the concrete and the direction of concrete
placement.
4.14.3 Cover for corrosion protection
4.14.3.1 General
For corrosion protection, the cover shall be not less than the appropriate value given in
Clauses 4.14.3.2 to 4.14.3.7.
4.14.3.2 Standard formwork and compaction
Where concrete is cast in formwork complying with AS 3610.1 and transported, placed and
compacted so as to—
(a) limit segregation or loss of materials;
TABLE 4.14.3.2
REQUIRED COVER WHERE STANDARD FORMWORK
AND COMPACTION ARE USED
classifications.
2 In construction, the specified position of reinforcements and tendons shall not
deviate from the required cover by more than the fixing tolerances specified in
Clause 17.7.3.
TABLE 4.14.3.3
REQUIRED COVER WHERE INTENSE COMPACTION
IS USED IN RIGID STEEL FORMWORK
TABLE 4.14.3.6
REQUIRED COVER FOR SPUN OR ROLLED MEMBERS
Concrete characteristic Cover
Exposure classification compressive strength ( f c )
MPa mm
A, B1 32 30
40 35
B2
50 30
C1 50 40
C2 50 45
5.1 GENERAL
The relevant authority shall determine whether a bridge is required to be designed for fire
resistance, and nominate the type of fire loading to be applied and fire resistance rating as
applicable.
Where the relevant authority determines that a non-hydrocarbon design fire resistance is
required, the relevant provisions of AS 3600 shall apply.
TABLE 5.4.1.1
COMPRESSIVE STRENGTH FACTOR
Temperature of concrete, °C 0 100 200 900 1200
k θ1 1.0 1.0 0.95 0.09 0
NOTE: Linear interpolation between values is permissible.
TABLE 5.4.1.2
COEFFICIENT OF THERMAL EXPANSION
Temperature of concrete, °C 0 to 200 200 to 700 700 to 1200
Coefficient of thermal expansion (10 -6 ), /°C 10 24 0
NOTE: Coefficient has a range of 20%.
TABLE 5.4.1.4
THERMAL CONDUCTIVITY
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TABLE 5.4.2.1(A)
TENSION REINFORCEMENT WITH STRAIN 2%
Temperature of reinforcement, °C 0 400 800 1200
k θ2 1.0 1.0 0.1 0.0
NOTE: Linear interpolation between values is permissible.
TABLE 5.4.2.1(B)
TENSION REINFORCEMENT WITH STRAIN 2%
OR COMPRESSION REINFORCEMENT
Temperature of reinforcement, °C 0 100 500 700 1200
k θ2 1.0 1.0 0.6 0.1 0.0
NOTE: Linear interpolation between values is permissible.
TABLE 5.4.2.2
MODULUS OF ELASTICITY FACTOR
Temperature of reinforcement, °C 0 100 500 700 1200
k θ3 1.0 1.0 0.6 0.13 0.0
NOTE: Linear interpolation between values is permissible.
TABLE 5.4.3.1
MINIMUM TENSILE STRENGTH FACTOR
Temperature of tendon, °C 0 100 700 1000
k θ4 1.0 1.0 0.05 0.0
NOTE: Linear interpolation between values is permissible.
TABLE 5.4.3.2
MODULUS OF ELASTICITY FACTOR
Temperature of tendon, °C 0 100 400 700 1000
k θ5 1.0 1.0 0.8 0.1 0.0
NOTE: Linear interpolation between values is permissible.
6.1 GENERAL
6.1.1 Basis for structural analysis
Analysis of concrete structures shall take into account the following:
(a) The strength and deformational properties of the member materials.
(b) The equilibrium requirements for all forces acting on and within the structure.
(c) The requirements of compatibility of deformations within the structure.
(d) The support conditions and, where appropriate, interaction of the structure with the
foundation and other connecting or adjacent structures.
6.1.2 Interpretation of the results of analysis
Irrespective of the method chosen for structural analysis, the simplifications, idealizations
and assumptions implied in the analysis shall be considered in relation to the real, three-
dimensional nature of the structure when the results of the analysis are interpreted.
NOTE: Users of software packages for analysis should ensure the package is appropriate for the
analysis being undertaken.
6.1.3 Methods of analysis
For the purpose of complying with the requirements for strength, serviceability, fatigue and
robustness specified in Section 2, it shall be permissible to determine the action effects and
deformations in a reinforced or prestressed structure and its component members using the
following methods, as appropriate:
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throughout the analysis. Particular account shall be taken of the effect of cracking on
torsional stiffness, which, in the absence of additional information, shall be not greater than
20% of the uncracked torsional stiffness at the strength ULS when checking for flexure of
slabs and beams.
NOTES:
1 For strength design of a regular rectangular framed structure, the cross-sectional stiffness of
the flexural members and columns may be taken as 0.4Ec If and 0.8EcI c respectively.
2 When modelling single cell box girders, account should be taken of the effect of torsion on
the distribution of shear between the webs (for example, adding the torsion divided by the
distance between the webs to the shear in one web).
6.2.4 Deflections
Deflection calculations shall take into account the effects of cracking, tension stiffening,
shrinkage, creep, thermal effects, relaxation of tendons, elastic shortening and settlement of
supports. Calculations in accordance with the requirements of Clauses 8.5 and 9.3 shall be
deemed to satisfy this requirement for beams and slabs respectively. Consideration shall be
given to any deformations that may result from construction staging and any deflection or
settlement of supporting temporary works.
6.2.5 Secondary bending moments and shears resulting from prestress
The secondary bending moments and shears and the associated deformations that are
produced in an indeterminate structure by prestressing shall be taken into account in the
design calculations for fatigue and serviceability.
The secondary bending moments and shears due to the effects of prestress may be
determined by elastic analysis of the unloaded uncracked structure.
regions, the redistribution of the moment at a support shall not exceed 30%.
(d) Where ku exceeds 0.2 in one or more peak moment regions, but does not exceed 0.4,
the redistribution shall not exceed 75 (0.4 ku)%.
(e) The positive bending moment shall be adjusted to maintain equilibrium.
(f) Where ku exceeds 0.4 in any peak moment region, no redistribution shall be made.
(g) Static equilibrium of the structure after redistribution of the moments shall be used to
evaluate all action effects for strength design.
(h) At column supports, the out of balance moment ( M v* ) shall not be varied during
moment redistribution.
NOTES:
1 The values of ku are calculated for cross-sections that have been designed on the basis of the
redistributed moment diagram.
2 The amount of redistribution is measured as a percentage of the bending moment before
redistribution.
3 Extra checks should be made on ductility and the possibility of punching shear failures.
Additional analysis shall be considered using other values of material properties to allow
for variability of material properties and the effects of non-proportionality in non-linear
analysis.
6.5.5 Sensitivity of analysis to input data and modelling parameters
Checks shall be made to investigate the sensitivity of the results of a non-linear frame
analysis to variations in input data and modelling parameters.
7.1 GENERAL
It shall be permissible to use strut-and-tie models to represent the conditions at overload
and at failure in non-flexural members and in non-flexural regions of members, as a basis
both for strength design and for evaluating strength.
A strut-and-tie model shall consist of compression elements (struts) and tension elements
(ties) that are connected together at nodes to form a load-resisting structural system.
Strut-and-tie models shall satisfy the following requirements:
(a) Loads shall be applied at nodes, and the struts and ties shall be subjected only to axial
force.
(b) The model shall provide load paths to carry the loads and other actions to the supports
or into adjacent regions.
(c) The model shall be in equilibrium with the applied loads and the reactions.
(d) In determining the geometry of the model, the dimensions of the struts, ties, and
nodal zones shall be taken into account.
(e) Ties shall be permitted to cross struts.
(f) Struts shall cross or intersect only at nodes.
(g) For reinforced concrete members at a node point, the angle between the axes of any
strut and any tie shall be not less than 30°.
(h) For prestressed concrete members at a node point, the angle between the axes of any
strut and any tie with a tendon acting as the reinforcement shall be not less than 20°.
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B ur st i n g for c e s
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(c) B ot t l e - s ha p e d c o m pre s s i o n fi e l d
A x i s of str ut
A x i s of t i e
θ
T
The value of the strength reduction factor (st) shall be obtained from Table 2.3.4.
Longitudinal reinforcement may be used to increase the strength of a strut. Such
reinforcement shall be placed parallel to the axis of the strut, located within the strut and
enclosed in ties or spirals satisfying Clause 10.7. The longitudinal reinforcement shall be
properly anchored. The strength of a longitudinally reinforced strut may be calculated as for
a prismatic, pin-ended short column of similar geometry.
7.2.4 Bursting reinforcement in bottle-shaped struts
The design bursting force at both the SLS Tb.s*
and ULS Tb* shall be calculated using an
equilibrium model consistent with the bottle shape shown in Figure 7.2.4(A). The
divergence angle () for the bottle-shaped strut shall be assessed for each situation but shall
be not less than—
(a) tan = 0.5 ................................................................................ for serviceability; and
(b) tan = 0.2 ............................................................................................... for strength.
The bursting force across the strut at cracking shall be taken as—
Tb.cr 0.7bl b f ct . . . 7.2.4(1)
where
b = width of rectangular cross-section or member
lb = length of the bursting zone [see Figure 7.2.4(A)]
If the calculated bursting force Tb* is greater than 0.5Tb.cr with tan taken as 0.5,
transverse reinforcement shall be provided in either—
(i) two orthogonal directions at angles 1 and 2 to the axis of the strut
[see Figure 7.2.4(B)]; or
(ii) one direction at an angle 1 to the axis of the strut, where 1 shall be not less than 40°
and shall satisfy—
where
Asi = area of reinforcement in directions 1 and 2 crossing a strut at an angle
1 to the axis of the strut [see Figure 7.2.4(B)]
fsi = serviceability limit stress in the reinforcement as specified in
Clause 12.7
The transverse reinforcement shall be evenly distributed throughout the length of the
bursting zone (lb), which shall be calculated from the following equation:
lb z 2 a 2 d c . . . 7.2.4(4)
where
a = shear span [see Figure 7.2.4(A)]
dc = width of the idealized strut [see Figure 7.2.4(A)]
z = projection of the inclined compressive strut normal to the shear span, [see
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Figure 7.2.4(A)]
a
Id ealize d parallel - s i d e d
str ut
CCC N o d e
Tb
/2 dc
/2
C
D z
/2
Tb
α C
/2
θ
CCT N o d e B ot t l e - s ha p e d str ut
L
) a
dc
+
(I b w w
2 5
0.
Ω Ω
d
c /2
d c /4
Tb
/2
/2
C d c /4
D z
/2
Tb
α C
/2
Ib
Ω
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w dc = w2 + Ω 2
d c /4
d c /4
A S1
A x i s of
str ut
γ1
γ2 S tr u t
A S2
7.3 TIES
7.3.1 Arrangement of ties
Ties shall consist of reinforcing steel and/or prestressing tendons. The reinforcement and/or
tendons shall be evenly distributed across the nodal regions at each end of the tie, and
arranged such that the resultant tensile force coincides with the axis of the tie in the strut-
and-tie model.
7.3.2 Design strength of ties
The design strength of a tie shall be taken as st [Astfsy + Ap(p.ef + p)] where ( p.ef + p)
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shall not exceed fpy. The value of st shall be obtained from Table 2.3.4.
7.3.3 Anchorage of ties
To provide adequate anchorage at each end of the tie, the reinforcement or tendon shall be
extended beyond the node to achieve the design strength of the tie at the node and anchored
in accordance with Clause 13.1. At least 50% of the development length (Lst) shall extend
beyond the nodal zone.
NOTE: Alternatively, anchorage of reinforcement may be achieved by a welded or mechanical
anchorage, located entirely beyond the nodal zone.
7.3.4 Design stress of reinforcement
The maximum stress in tie reinforcement at SLS shall be not greater than fscr given in
Table 8.6.1(A) for the largest nominal diameter (d b) of the bars in the tie.
7.4 NODES
7.4.1 Types of nodes
Three types of node are distinguished by the arrangement of the entering struts and ties, and
the confinement thus provided, as follows:
(a) CCC—there are only struts entering the node.
(b) CCT—there are two or more struts and a single tension tie entering the node.
(c) CTT—there are two or more tension ties entering the node.
(b) the strain in the extreme compression fibre may be adjusted to obtain the maximum bending
strength.
8.1.3 Rectangular stress block
Clause 8.1.2 shall be deemed to be satisfied for the concrete provided—
(a) the maximum strain in the extreme compression fibre is taken as 0.003; and
(b) a uniform compressive stress of 2 f c acts on an area bounded by—
(i) the edges of the cross-section; and
(ii) a line parallel to the neutral axis under the loading concerned, and located at a
distance kud from the extreme compressive fibre, where—
2 1.0 0.003 f c (within the limits of 0.67 2 0.85) . . . 8.1.3(1)
Sections with kuo greater than 0.36 and M* > 0.6Muo shall be used only when—
(a) the structural analysis is carried out in accordance with Clauses 6.2 to 6.6; and
(b) compressive reinforcement of at least 0.01 times the area of concrete in compression
is used and restrained by fitments as specified in Clause 10.7.4.
8.1.6 Minimum strength requirements
8.1.6.1 General
The ultimate strength in bending (Muo), without axial force, at critical cross-sections shall
be not less than (Muo)min, the minimum required strength in bending at a critical cross-
section, and calculated using the following equation:
M uo min 1.2 [ Z f ct.f
Pe / Ag Pe e] . . . 8.1.6.1(1)
where
Z = section modulus of the uncracked cross-section, referred to the extreme fibre
at which flexural cracking occurs
= characteristic flexural tensile strength of concrete at 28 days
f ct.f
Pe = total effective prestress force allowing for all losses of prestress
e = eccentricity of the prestressing force (Pe), measured from the centroidal axis
of the uncracked section
This requirement may be waived at critical sections of a statically indeterminate member,
provided it can be demonstrated this will not lead to sudden collapse of a span or a reduced
collapse load.
For reinforced concrete cross-sections, this requirement shall be deemed to be satisfied for
the direction of bending being considered if tensile reinforcement of the cross-sectional
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where
For rectangular sections:
b = 0.20
For T-sections and L-sections with the web in tension:
1/ 4
b D b
b 0.20 ef 1 0.4 s 0.18 0.20 ef
bw D bw
For T-sections and L-sections with the flange in tension:
2/3
b D b
b 0.20 ef 1 0.25 s 0.08 0.20 ef
bw D bw
8.1.6.2 Prestressed beams at transfer
The strength of a prestressed beam at transfer shall be checked using the load combinations
specified in AS 5100.2 and a capacity reduction factor () for the section of 0.6.
This requirement shall be deemed to be satisfied if the maximum compressive stress in the
concrete, under the loads at transfer, does not exceed 0.5fcp for a rectangular distribution of
stress or 0.6fcp for a triangular distribution of stress, and flexural cracking is controlled in
accordance with Clause 8.6.2.
if f py f pb 0.9 ,
k1 = 0.28;
k2
1
bef d p f c
Apt f pb Ast Asc f sy . . . 8.1.7(2)
Compressive reinforcement may be taken into account only if dsc, the distance from the
extreme compressive fibre of the concrete to the centroid of compressive reinforcement, is
not greater than 0.15dp, in which case k2 shall be taken as not less than 0.17.
8.1.8 Stress in tendons not yet bonded
Where the tendon is not bonded, the stress in the tendon at the strength ULS (pu) shall be
determined from the following equation, but in no case shall pu be greater than fpy:
d p ku d
pu p.cf 6200 . . . 8.1.8(1)
L
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pc
where
p.cf = effective stress in the tendon (after losses)
kud = neutral axis depth
Ap f py Ast Asc f sy 0.85 b bw d f f c
= for a T-section . . . 8.1.8(2)
0.85 bw f c
k2 d p
= for a rectangular section . . . 8.1.8(3)
0.85
df = thickness of the compression flange
k2 = as given in Equation 8.1.7(2)
Lpa
Lpe = . . . 8.1.8(4)
1 s
n
2
Lpa = length of the tendons
ns = number of support hinges crossed by the tendon (draped tendons only)
where
sd = centre-to-centre distance between lines of ducts in the plane of the curvature
Pi = prestressing force after initial losses
r = radius of curvature of the duct
At all other locations where tendons curve or deviate, the adequacy of the concrete to carry
the lateral force shall be assessed and, where necessary, the lateral load shall be carried by
reinforcement designed in accordance with Section 12.
8.1.9.4 Out-of-plane forces
Curved tendons with multiple strands or wires also induce out-of-plane forces perpendicular
to the plane of the tendon curvature. The distributed splitting force along the line of the
tendon may be estimated as 0.16P/r in addition to any bursting forces calculated in
accordance with Clause 7.2.4.
The out-of-plane splitting force shall be deemed to be resisted over a distance dsp from the
duct, that is, towards the centre of curvature, equal to the lesser of—
(a) twice the distance between the centre-line of the duct and the closest outer layer of
non-prestressed reinforcement parallel to the plane of curvature of the duct; and
(b) the clear distance between two ducts in the same or similar planes of curvature.
The splitting force may be resisted by the concrete in tension or by reinforcement designed
in accordance with Section 12. The concrete tensile capacity may be taken as f ct , where ϕ
is equal to 0.6. Transverse reinforcement, if required, shall be spaced at no greater than the
lesser of 300 mm and dsp.
NOTE: For guidance, see EN 1992-2.
and
Acp = total area enclosed by outside perimeter of concrete section
Tcr = torsional cracking moment
uc = the length of the outside perimeter of concrete cross-section
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A1 The equivalent factored shear force ( Veq* ) at any section for co-existing applied shear (V*)
and applied torsion (T*) shall be taken equal to the following:
(a) For solid sections:
2
0.9T *uh
Veq* V
* 2
. . . 8.2.1.2(4)
2 Ao
(b) For box sections:
T *d s
Veq* V * . . . 8.2.1.2(5)
2 Ao
where
uh = perimeter of the centre-line of the closed transverse torsion reinforcement
ds = distance from the extreme compression fibre to the centroid of non-prestressed
tensile reinforcement
8.2.1.3 Vertical component of prestress
Where the vertical component of the prestressing force (Pv) at the section under
consideration is greater than the minimum design shear force (V* min), the following
additional design action shall be considered:
V* = 1.2Pv V*min . . . 8.2.1.3
where
V*min= minimum design shear force for all load combinations
A1 In this case, Pv shall be taken as zero for the determination of the shear capacity in
Clauses 8.2.1.6, 8.2.3.1, 8.2.3.3, 8.2.4.5 and 8.2.7.
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where
s = centre-to-centre spacing of shear reinforcement, measured parallel to the
longitudinal axis of the member
8.2.1.8 Design yield strength of tendons as transverse shear reinforcement
The design yield strength of tendons used as transverse shear reinforcement shall be taken
as the effective prestress plus 500 MPa, but shall not be taken greater than fpy.
8.2.1.9 Effective shear depth
The effective shear depth (dv) shall be taken as the distance between the resultants of the
tensile and compressive forces due to flexure in Clause 8.1.2 but not less than the greater of
0.72D or 0.9d, where d is taken as the distance from the extreme compression fibre to the
centroid of the longitudinal tension reinforcement in the half-depth of the section
containing the flexural tension zone.
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(ii) the transverse shear reinforcement required at do from the support is continued
unchanged to the face of the support.
For concentrated loads near a support, either the maximum transverse shear shall be taken
at the face of the support or more refined modelling techniques shall be used to consider the
enhanced effect of loads taken directly to a support such as strut-and-tie action (see
Clause 8.2.2.1).
8.2.3.3 Shear strength limited by web crushing
In no case shall the ultimate shear strength (Vu) at any section be taken as greater than—
A1
Vu.max cot v cot v
0.55 f cbv d v P ; or
= 1 cot 2 v . . . 8.2.3.3(1)
v
cot v cot v
0.55 0.9 f cpbv d v P , at transfer
= 1 cot 2 v . . . 8.2.3.3(2)
v
where
Vu.max = ultimate shear strength limited by web crushing failure
dv = effective shear depth (see Clause 8.2.1.9)
and
v = angle between the axis of the concrete compression strut and the
longitudinal axis of the member (see Clause 8.2.4.2)
A1
αv = angle between the inclined shear reinforcement and the longitudinal tensile
reinforcement
8.2.4 Concrete contribution to ultimate shear strength of a beam (Vuc)
8.2.4.1 General
A1 The shear strength shall be calculated as follows:
Vuc k v f cbv d v . . . 8.2.4.1
0.4 1300
kv . . . 8.2.4.2(1)
1 1500 x 1000 kdg d v
where
(i) f c 65 MPa —
32
kdg but not less than 0.80
16 d g
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. . . 8.2.4.2(2)
where
dg = maximum nominal aggregate size
or
(ii) f c 65 MPa —
kdg = 2.0 . . . 8.2.4.2(3)
Provided the maximum nominal aggregate size (dg) is not less than 16 mm, kdg may be
taken as 1.0.
(b) For sections with transverse reinforcement equal or greater than minimum shear
reinforcement (Asv Asv.min)—
0.4
kv . . . 8.2.4.2(4)
1 1500 x
The angle of inclination of the concrete compression strut and the longitudinal axis of the
member (v) shall be calculated as follows:
v = (29 + 7000x) . . . 8.2.4.2(5)
(c) Ast and Apt are the areas of reinforcing bars and prestressing tendons in the half-depth
of the section containing the flexural tension zone.
NOTES:
1 fpo may be taken as 0.7fpb for bonded tendons outside the transfer length and p for
unbonded tendons.
2 In calculating Ast, the area of bars that terminate less than their development length from
the section under consideration shall be reduced in proportion to their lack of full
development.
NOTE: For sections closer than d o to the face of the support, the value of x calculated at d o from
the face of the support may be used in evaluating and kv.
If the axial tension is large enough to crack the flexural compression face of the section, the
resulting increase in x shall be taken into account. In lieu of more accurate calculations, x
calculated from the equation shall be doubled.
v and kv may be determined from Clause 8.2.4.2 using a value of x that is greater than that
calculated from the equation in this Clause. x shall be taken as not greater than 3.0 103.
0.9T *uh
V
* * 2
M dv Pv . . . 8.2.4.4(3)
2 Ao
(b) N* is taken as positive for tension and negative for compression.
NOTE: For rigid frames and rectangular culverts, the value of N* used to determine x may be
taken as twice the compressive axial thrust calculated by elastic analysis.
(c) Ast and Apt are the areas of reinforcing bars and prestressing tendons in the half-depth
of the section containing the flexural tension zone.
NOTES:
1 fpo may be taken as 0.7fpb for bonded tendons outside the transfer length and p for
unbonded tendons.
2 In calculating Ast, the area of bars that terminate less than their development length from
the section under consideration may be reduced in proportion to their lack of full
development.
(d) Act = area of concrete calculated from the mid-depth of the section on flexural tension
side.
NOTE: For sections closer than d o to the face of the support, the value of x calculated at d o from
the face of the support may be used in evaluating v and kv.
If the axial tension is large enough to crack the flexural compression face of the section, the
resulting increase in x shall be taken into account. In lieu of more accurate calculations, x
calculated from the equation shall be doubled.
v and kv may be determined from Clause 8.2.4.2 using a value of x that is greater than that
calculated from the equation in this Clause. However, x shall be taken as not greater than
+3.0 103.
where
Aoh = area enclosed by centre-line of exterior closed transverse torsion
reinforcement, including area of holes (if any)
uh = perimeter of the centre-line of the closed transverse torsion reinforcement
Vu,max = ultimate shear strength limited by web crushing failure, in accordance with
Clause 8.2.3.3
8.2.4.6 Determination of v and kv for non-prestressed components (simplified method)
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For non-prestressed components not subjected to axial tension, and provided the specified
yield strength of the longitudinal reinforcement does not exceed 500 MPa, the design
concrete strength does not exceed 65 MPa and the size of maximum aggregate particle is
not less than 10 mm, the angle of inclination (v) shall be taken as 36°, and the value of kv
shall be determined as follows:
A1 (a) For Asv < Asv.min kv = 200/(1000 + 1.3dv) 0.10 . . . 8.2.4.6
(b) For Asv Asv.min kv = 0.15
8.2.4.7 ‘Text deleted’
A1
A1 8.2.5 Transverse shear and torsional reinforcement contribution to the ultimate shear
strength of a beam (Vus )
8.2.5.1 General
Where the spacing (s) of the transverse shear reinforcement changes, the quantity Asv/s may
be assumed to vary linearly over a length, D, centred on the location where the spacing
changes.
8.2.5.2 Transverse reinforcement for shear
A1
The contribution to the design shear strength (Vu) by shear reinforcement in a beam (Vus)
shall be determined from the following equations:
(a) For perpendicular shear reinforcement:
Vus = (Asvfsy.fdv/s)cotv . . . 8.2.5.2(1)
(b) For inclined shear reinforcement:
Vus = (Asvfsy.fdv/s)(sinvcotv + cosv) . . . 8.2.5.2(2)
where
v = angle between the inclined shear reinforcement and the longitudinal
tensile reinforcement
8.2.5.3 Transverse reinforcement for combined shear and torsion
For sections subjected to combined shear and torsion, the transverse reinforcement that is
provided shall be at least equal to the sum of that required for shear and that required for
the coexisting torsion.
8.2.5.4 Transverse reinforcement for torsion
The amount of transverse reinforcement required for torsion shall be such that T* ϕTus.
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Ftd V * p Pv 0.5Vus cot v
. . . 8.2.7(2)
Fcd V * p Pv 0.5Vus cot v Fc* . . . 8.2.8(2)
where Fc* is the absolute value of the design force in the compressive zone due to flexure
and axial actions.
Additional reinforcement (As) and/or additional tendons (Ap) shall be anchored and
proportioned such that the following is satisfied:
Asfsy + Appu Fcd/
where
= 0.7 [see Table 2.3.2(c)]
Reinforcement and tendons shall be developed in accordance with Clause 13.1.
NOTE: The reinforcement and tendons calculated in this Clause are additional to that calculated
for bending and axial actions.
8.2.9 Extension of longitudinal reinforcement and tendons
8.2.9.1 General
A1 At every section, the longitudinal reinforcement and tendons shall be designed to resist the
flexural design force determined in Clause 8.1.5, axial design force determined in
accordance with Section 10 and additional longitudinal forces caused by shear and torsion
as specified in Clause 8.2.7, Clause 8.2.8 and Figure 8.2.9.1.
For members not subjected to significant direct tension or torsion, these requirements may
be satisfied by extending the flexural tension reinforcement and tendons to develop the
flexural tensile force beyond the location required by flexure alone as follows:
(a) Where transverse reinforcement is not required, a distance D.
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LEGEN D:
A
A = Enve l o p e of M */z + N */2
B = Ac t i n g te n s i l e for c e Δ F t d
C = R e s i s t i n g te n s i l e for c e ØT u
B Δ F td
C
d 0 c ot(θ v )
d 0 c ot(θ v ) A
Δ F td
C B
cross-sectional area required to resist the maximum moment acting alone, where the support
or the load at the maximum moment location introduces direct compression into the flexural
compression face of the member and the member is not subject to significant torsion.
A1 8.2.9.3 ‘Text deleted’
This requirement shall be deemed to be satisfied if any one of the following conditions is
met:
(a) Not more than a quarter of the maximum tensile reinforcement or tendons is
terminated within any distance 2D.
(b) At the cut-off point, ϕVu Veq* .
(c) Stirrups are provided to give an area of shear reinforcement of Asv + Asv.min for a
distance equal to the overall depth of the cross-section (D) along the terminated bar
beyond the cut-off point, where Asv.min and Asv are determined in accordance with
Clause 8.2.1.7 and Clause 8.2.5.2 respectively.
8.3.1.4 Anchorage of flexural reinforcement
Notwithstanding the requirements of Clause 8.2.9, the anchorage of longitudinal flexural
reinforcement for the positive moment tensile reinforcement provided at midspan shall be—
(a) not less than one half shall extend into a simple support for a length of 12db; and
(b) not less than one quarter shall extend into a support where the beam is continuous or
flexurally restrained.
8.3.1.5 Restraint of compressive reinforcement
Compressive reinforcement required for strength in beams shall be restrained by fitments in
accordance with Clause 10.7.4.
8.3.1.6 Bundled bars
Groups of parallel longitudinal bars bundled to act as a unit shall—
(a) have not more than four bars in any one bundle;
(b) be tied together in contact; and
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NOTE: Straight reinforcement or tendons may be permissible provided they are fully anchored at
both the top and bottom of a member.
8.3.2.2 Spacing
Shear reinforcement shall be spaced longitudinally not further apart than 0.5D or 300 mm,
whichever is less.
The maximum transverse spacing across the width of the member shall not exceed the lesser
of 600 mm and D.
8.3.2.3 Extent
The shear reinforcement required at the critical cross-section shall be carried to the face of
the support.
Shear reinforcement of area not less than that calculated as being necessary at any cross-
section shall be provided for a distance (D) from that cross-section in the direction of
decreasing shear. The first fitment at each end of a span shall be positioned not more than
50 mm from the face of the adjacent support.
Shear reinforcement shall extend as close to the compression face and the tension face of
the member as cover requirements and the proximity of other reinforcement and tendons
will permit.
8.3.2.4 Anchorage of shear reinforcement
The anchorage of shear reinforcement transverse to the longitudinal flexural reinforcement
may be achieved by a hook or cog complying with Clause 13.1.2.7 or by lapped splices.
Where lapped splices are used, the lap lengths shall be calculated in Clause 13.1.2, except
that for stirrups or fitments adjacent to the cover concrete a hook shall be provided at the
end of each lapped bar, and the lap length calculated in Clause 13.1.2 shall be multiplied by
1.3.
Shear reinforcement shall be deemed to be anchored provided the following criteria are
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met:
(a) Bends in bars used as fitments shall enclose a longitudinal bar with a diameter not
less than the diameter of the fitment bar. The enclosed bar shall be in contact with the
fitment bend.
Where a fitment hook is located in the compression zone of the structural member,
where anchorage conditions are most favourable, the stirrup spacing shall comply
with Clause 8.3.2.1. Provided the hook complies with Clause 13.1.2.7, anchorage
shall be deemed to be satisfied.
(b) Where a fitment hook is located in the tension zone, the anchorage specified in
Item (b) shall be deemed to be satisfied, provided the stirrup spacing calculated in
accordance with Clause 8.2.5.1 is multiplied by 0.8 and the maximum spacing
specified in Clause 8.3.2.1 is multiplied by 0.8.
(c) Fitment cogs shall not be used when the anchorage of the fitment is solely in the outer
layer of reinforcement. In this case fitment hooks shall be used.
NOTE: The type of anchorage used should not induce splitting or spalling of the concrete cover.
8.3.2.5 End anchorage of mesh
Where mesh is used as shear reinforcement, the ends shall be anchored—
(a) in accordance with Clause 8.3.2.3, if the wires are bent at least to the dimensions of a
standard fitment hook; or
(b) by embedding two or more transverse wires at least 25 mm within the compressive
zone.
8.4.1 General
This Clause applies to the transfer of longitudinal shear forces, across interface shear planes
through webs and flanges of—
(a) composite beams constructed of precast concrete sections and cast in situ toppings or
flanges; and
(b) beams constructed monolithically.
8.4.2 Design shear stress
The design shear stress ( *) acting on the interface shall be taken as follows:
* = Veq*/(zbf) . . . 8.4.2
where
z = internal moment lever arm of the section
For a shear plane that passes through a region in compression—
= ratio of the compressive force in the member (calculated between the
extreme compressive fibre and the shear plane) and the total compression
force in the section
fsy = characteristic yield strength of shear reinforcement not exceeding 500 MPa
s = spacing of anchored shear reinforcement crossing interface
TABLE 8.4.3
SHEAR PLANE SURFACE COEFFICIENTS
Coefficients
Surface condition of the shear plane
k co
A smooth surface, as obtained by casting against a form, or finished to a similar
0.6 0.1
standard
A surface trowelled or tamped, so that the fines have been brought to the top, but
where some small ridges, indentations or undulations have been left; slip-formed 0.6 0.2
and vibro-beam screeded; or produced by some form of extrusion technique
A surface deliberately roughened—
(a) by texturing the concrete to give a pronounced profile;
(b) by compacting but leaving a rough surface with coarse aggregate protruding
but firmly fixed in the matrix; 0.9 0.4
(c) by spraying when wet, to expose the coarse aggregate without disturbing it;
or
(d) by providing mechanical shear keys.
Monolithic construction 0.9 0.5
NOTE: Where a beam is subjected to high levels of differential shrinkage, temperature effects,
tensile stress or fatigue effects across the shear plane, the values of and k co in the above Table do
not apply.
For the purpose of the above determinations, the value of Ief at each of the cross-sections
nominated in Items (a) to (c) above shall be given by the following:
A1
I cr
I ef 2
I ef.max
I M cr.t . . . 8.5.3.1
1 1 cr *
I Ms
where
Ief.max = maximum effective second moment of area, taken as I for reinforced
sections when p = Ast/(bd) 0.005 and prestressed sections
= 0.6 I, for reinforced sections when p = Ast/(bd) < 0.005
b = width of the rectangular cross-section at the compression face
M s* = maximum bending moment at the section, based on the short-term
serviceability load or the construction load
Mcr
σ cs P / Ag Pe 0
= Z f ct.f
Z = section modulus of the uncracked section, referred to the extreme
fibre at which cracking occurs
= characteristic flexural tensile strength of concrete
f ct.f
cs = maximum shrinkage-induced tensile stress on the uncracked section
at the extreme fibre at which cracking occurs
In the absence of more refined calculation, cs may be taken as—
= 2.5 pw 0.8 pcw
Es cs
1 50 pw
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(e)
not exceed the larger of the maximum steel stresses given in—
(i) Table 8.6.1(A) for the largest nominal diameter (db) of the bars in the tensile
zone; and
(ii) Table 8.6.1(B) for the largest centre-to-centre spacing of adjacent parallel bars
in the tensile zone.
Bars with a diameter less than half the diameter of the largest bar in the section shall
be ignored when determining spacing.
NOTE: Design bending moments M s* at the SLS are typically estimated using elastic analysis.
Significant errors may result if they are determined from the design bending moments M* at the
strength limit state when the amount of moment redistribution is unknown; for example, if plastic
methods of analysis are used for strength design.
TABLE 8.6.1(A)
MAXIMUM STEEL STRESS FOR TENSION OR FLEXURE
Loading case specified in Loading case specified in
Nominal bar diameter (db ) Item (c)(i) Item (c)(ii)
mm Maximum steel stress (f scr )
MPa
10 360 275
12 330 250
16 280 215
20 240 185
24 210 160
28 185 140
32 160 125
36 140 110
40 120 95
NOTES: Values for other bar diameters may be calculated using the appropriate equations, as
follows:
(a) f scr = [760 – 173log e (d b )] MPa for loading case specified in Item (c)(i).
(b) f scr = [575 – 130log e (d b )] MPa for loading case specified in Item (c)(ii).
TABLE 8.6.1(B)
MAXIMUM STEEL STRESS FOR FLEXURE
Loading case specified in Loading case specified in
Centre-to-centre spacing Item (c)(i) Item (c)(ii)
mm Maximum steel stress (f scr )
MPa
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50 360 280
100 320 240
150 280 200
200 240 160
250 200 120
300 160 80
NOTES: Values for other centre-to-centre spacings may be calculated using the appropriate
equation, as follows:
(a) f scr = [400 (0.8 centre-to-centre spacing)] MPa for loading case specified in
Item (c)(i).
(b) f scr = [320 (0.8 centre-to-centre spacing)] MPa for loading case specified in
Item (c)(ii).
(b) the increment in steel stress near the tension face to that given in Table 8.6.2.1, as the
load increases from its value when the extreme concrete tensile fibre is at zero stress
to the SLS load combinations values.
TABLE 8.6.2.1
MAXIMUM INCREMENT OF STEEL STRESS
FOR FLEXURE IN PRESTRESSED BEAMS
compression under a SLS load combination that comprises permanent effects plus 25% of
the transient serviceability load(s).
8.6.3 Crack control in the side face of beams
For crack control in the side face of beams where the overall depth exceeds 750 mm,
longitudinal reinforcement, consisting of 12 mm bars at 200 mm centres or 16 mm bars at
300 mm centres, shall be placed in each side face.
8.6.4 Crack control at openings and discontinuities
Reinforcement shall be provided for crack control at openings and discontinuities in a
beam.
8.8.2 Effective width of flange for strength and serviceability for T-beams and
L-beams
In the absence of a more accurate determination, the effective width of the flange for
strength and serviceability shall be taken as—
(a) for T-beams .................................................................................. bef = bw + 0.2a; and
(b) for L-beams ........................................................................................ bef = bw + 0.1a,
where a is the distance between points of zero bending moment, which, for continuous
beams, may be taken as 0.7L.
In both Items (a) and (b) above, the overhanging part of the flange considered effective
shall not exceed half the clear distance to the next parallel member. The effective width so
determined may be taken as constant over the entire span.
Ca st- in - p l ac e
c o n c rete
Ca st- in - p l ac e
c o n c rete
Methods of calculating the effects of residual creep and differential shrinkage shall be as
specified in Clause 8.10.3.2.
Residual creep and differential shrinkage in a composite member shall be regarded as
always acting together.
8.10.2.2 Analysis
The following assumptions shall be applied:
(a) The effective width of the concrete slab shall be used in the design of a concrete
member and shall be determined in accordance with Clause 8.8.
(b) The effective cross-sectional area of the concrete slab shall be transformed to an
equivalent area of beam concrete by applying the modular ratio factor (αc) of the slab
concrete and the beam concrete in the composite member.
8.10.3 Design for applied loads
8.10.3.1 General
All components and composite members shall be designed in accordance with this Section
for all loads to which they are subjected.
NOTE: Particular attention should be given to the validity of any assumptions about concrete
stress-strain relationships being adopted when high compression stresses occur at SLS.
8.10.3.2 Effects due to residual creep and differential shrinkage
8.10.3.2.1 General
Residual creep is that portion of the creep that occurs in the precast element after
establishing composite action.
The procedures in Clauses 8.10.3.2.2 and 8.10.3.2.3 shall be used to determine the effects
of residual creep in a composite member subject to dead load and prestress only, and the
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where
cc.j residual creep coefficient, which depends on the amount of creep strain
= that will occur after the precast beam and the cast-in-place concrete are
made composite
The final stresses in the composite section due to dead load (precast beam and cast-
in-place concrete), prestress and creep shall be the sum of stresses in Item (i) and the
stresses due to residual creep.
(b) Continuous members Stresses in a continuous composite member due to dead load,
prestress after all losses and creep shall be calculated by considering the continuous
member separated into simply supported spans, and then restoring continuity by
applying restraint moments at the supports. The final stresses at any section shall be
the sum of the stresses occurring in each simply supported span calculated in
accordance with Item (a) above and those stresses caused by 1 e cc.j the continuity
restraint moments resulting from the application of both the dead load and prestress to
the continuous composite section [described in Item (a)(ii)].
The restraint moments may be calculated by any method using elastic analysis. The restraint
moment calculation shall be based on the assumption that continuity and composite action
are established in all spans simultaneously at time (tj). A minimum and maximum estimated
value of tj shall be used in the calculation of creep and shrinkage effects.
NOTE: In a composite member, creep occurring in the precast beam results in a redistribution of
stresses between the beam and the cast-in-place concrete slab. The magnitude of these stresses
depends on the age of the precast beam when composite behaviour is established. If a large
proportion of the creep in the beam has taken place by the time the slab is cast, the effect of
subsequent creep will be small.
8.10.3.2.3 Effect of differential shrinkage
Differential shrinkage effects between the precast beam and the cast-in-place concrete shall
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be evaluated as follows:
(a) Simply supported members Stresses and deformations in the composite member, due
to differential shrinkage, shall be evaluated assuming a uniform differential shrinkage
force along the member calculated as follows:
1 e cc.j
differential shrinkage force = Ec Acscs.j . . . 8.10.3.2.3
cc.j
where
Acs = area of cast-in-place concrete
TABLE 8.10.3.2.3
FACTORS USED FOR RESIDUAL CREEP AND DIFFERENTIAL SHRINKAGE
CALCULATIONS IN COMPOSITE MEMBERS
cc.j
1 e 0 0.393 0.632 0.865 0.950 0.982 0.993
cc.j
1 e
1.0 0.787 0.632 0.432 0.317 0.245 0.199
cc.j
The analysis of the continuous member shall be based on the assumption of uniform
moment of inertia using the uncracked cross-section including the actual width of the
member.
The time-dependent effects of creep and shrinkage shall be calculated in accordance with
Clause 8.10.3.2.
8.10.3.3.2 Positive moment connection at supports
In addition to those positive moments due to live load, support settlement and thermal
effects, positive moments can develop due to the combined effects of differential creep and
shrinkage. Where positive moments occur at supports, fully anchored non-prestressed
longitudinal reinforcement shall be cast into the ends of the precast beams to permit the
connection of the bottom flanges of adjoining beams at supports. Reinforcement shall be
designed for the SLS in accordance with Clause 8.6.1.
The reinforcement shall be spliced in accordance with Section 13.
NOTE: If overlapping cogged bars or hooked bars are used, the distance between the end face of
the beam and the inside edge of the leg of the bar projecting from the beam should be not less
than 12 times the bar diameter.
8.10.3.3.3 Negative moment zones
The value of f c for the beam concrete and the width of the bottom flange of the beam shall
be used in the strength calculation for the cross-section directly over internal supports.
The negative moment reinforcement shall be distributed evenly within the effective width
and extended at the same rate beyond that area.
8.10.4 Shear
The shear resistance of a composite section shall be in accordance with Clause 8.2.
The interface shear connection shall be in accordance with Clause 8.4.
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L
(Minimum 30%)
For main reinforcement perpendicular to traffic, the amount of distribution
reinforcement in the outer quarters of the span may be reduced by a maximum of
50%.
For rail bridges, the distribution reinforcement for slabs shall be based on a rational
analysis using rail traffic loading as specified in AS 5100.2.
9.1.3 Edge stiffening
Edge stiffening of slabs shall be considered as follows:
(a) Longitudinal Edge beams shall be provided for all slabs having main reinforcement
parallel to traffic. An edge beam may consist of a kerb section, a beam integral with
the slab, or a slab edge additionally reinforced or extended.
(b) Transverse Transverse edges at the ends of the bridge and at intermediate points
where the continuity of the slab is disrupted shall be additionally reinforced or
supported by edge beams or diaphragms designed for the full effects of the wheel
loads.
The need for longitudinal or transverse edge stiffening of slabs shall be based on a rational
analysis of the slab using the specified loadings plus any other loading that may be applied
to the edge of the slab during the life of the structure.
where
u = length of the critical shear perimeter as defined below
dom = mean value of do, averaged around the critical shear perimeter (u)
fcv = concrete shear strength, given by
2 . . . 9.2.3(3)
0.171 f c 0.34 f c
h
σcp = average intensity of effective prestress in the concrete
h = ratio of the longest overall dimension of the effective loaded area (Y) to the
shortest overall dimension (X) measured perpendicular to Y (see
Figure 9.2.3)
For the purpose of this Clause, the critical shear perimeter (u) is defined by a line
geometrically similar to the boundary of the effective area of a support or load and located
at a distance of dom/2 from the boundary as shown in Figure 9.2.3. The effective area of a
support or load shall be that area totally enclosing the actual support or load for which the
perimeter is a minimum.
That part of the critical shear perimeter that is enclosed by radial projections from the
centroid of the support or load to the extremities of any critical opening shall be regarded as
ineffective.
An opening shall be regarded as critical if it is located at a clear distance of less than 2.5bo
from the critical shear perimeter, where bo is the width of the critical opening as shown in
Figure 9.2.3(b).
bo
Cr it i c al s h ear
p er i m eter
Cr it i c al s h ear
p er i m eter In ef fe c t i ve
< 2 . 5b o portion
dom
2
dom dom
In ef fe c t i ve
X 2 2 portion
Y
Y < 2 . 5b o
dom
2
B o u n d ar y of ef fe c t i ve X
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For areas of slabs fully enclosed within a building except for a brief period of weather
exposure during construction and, where it is assessed that crack control is not required,
only Item (a) and Item (b) shall be satisfied.
NOTE: Design bending moments M s* at the SLS are typically estimated using elastic analysis.
Significant errors may result if they are determined from the design bending moments M* at the
strength limit state when the amount of moment redistribution is unknown; for example, if plastic
methods of analysis are used for strength design.
TABLE 9.4.1(A)
MAXIMUM STEEL STRESS FOR FLEXURE
IN REINFORCED SLABS—NOMINAL DIAMETER
TABLE 9.4.1(B)
MAXIMUM STEEL STRESS FOR FLEXURE
IN REINFORCED SLABS—CENTRE-TO-CENTRE SPACING
Centre-to-centre spacing Maximum steel stress (f scr )
mm MPa
50 360
100 320
150 280
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200 240
250 200
300 160
NOTE: Intermediate values may be calculated using the following equation:
Maximum steel stress = 0.8 centre-to-centre spacing + 400 MPa.
(b) the increment in steel stress near the tension face to that given in Table 9.4.2, as the
load increases from its value when the extreme concrete tensile fibre is at zero stress
to the SLS load combination value.
For prestressed members in exposure classifications B2, C1, C2 or U, the concrete at the
level of each tendon shall be in compression under the SLS load combinations that
comprises permanent effects plus 50% of the transient serviceability load(s).
TABLE 9.4.2
MAXIMUM INCREMENT OF STEEL STRESS
FOR FLEXURE IN PRESTRESSED SLABS
Nominal reinforcement Maximum increment of steel stress f c MPa
bar diameter (d b )
mm D s 300, mm D s > 300, mm
10 320 360
12 300 330
16 265 280
20 240
24 210
28 200
All bonded tendons 200
(b) The reinforcement calculated using Equation 9.4.3 shall be placed equally with half
on each face of the slab and located as close to each face as cover and detailing
permit. Deff shall be taken as—
(i) D, where D is less than 500 mm; or
(ii) 500 + 0.2(D 500), where D is greater than 500 mm.
9.4.4 Crack control at openings and discontinuities
For crack control at openings and discontinuities in a slab, additional, properly anchored,
reinforcement shall be provided.
9.4.5 Crack control in the vicinity of restraints
In the vicinity of restraints, special attention shall be paid to the internal forces and cracks
which may be induced by prestressing, shrinkage or temperature.
10.1 GENERAL
10.1.1 Design strength
The design strength of a column shall be determined by its ability to resist the axial forces
and bending moments caused by the design loading for strength and any additional bending
moments produced by slenderness effects.
10.1.2 Minimum bending moment
At any cross-section of a column, the design bending moment about each principal axis
shall be taken to be not less than N* times 0.05D, where D is the overall depth of the
column in the plane of the bending moment.
10.1.3 Definitions
For the purpose of this Section the definitions below apply.
10.1.3.1 Braced column
Column in a structure for which the lateral actions applied at the ends in the direction under
consideration are resisted by components such as shear walls or lateral bracing.
10.1.3.2 Short column
Column in which the additional bending moments due to slenderness can be taken as zero.
10.1.3.3 Slender column
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Column that does not satisfy the requirements for a short column.
c 1 / 3.5 N * / 0.6 N uo for N*/0.6Nuo < 0.15
b = km/(1N*/Nc) 1 . . . 10.4.2
where
Nc = buckling load given in Clause 10.4.4
km = 0.6 0.4M *
/ M 2* but shall be taken as not less than 0.4, except that if the
1
column is subjected to significant transverse loading between its ends and in
the absence of more exact calculations, km shall be taken as 1.0
10.4.3 Moment magnifier for an unbraced column
The moment magnifier ( ) for an unbraced column shall be taken as the larger value of b or
s where—
(a) b for an individual column is calculated in accordance with Clause 10.4.2, assuming
the column is braced; and
(b) s for each column in a bent is calculated as—
1/(1N*/Nc) . . . 10.4.3(1)
where the summations include all columns within the storey and Nc is calculated for
each column in accordance with Clause 10.4.4.
As an alternative to Item (b), s may be calculated from a linear elastic critical buckling
load analysis of the entire frame, where s is taken as a constant value for all columns given
by the following equation:
s 1 /1 1 d / s uc . . . 10.4.3(2)
where
d = N G* N * and taken as zero when Le/r 40 and N* M*/2D
10.5 SLENDERNESS
10.5.1 General
The slenderness ratio (Le/r) of a column shall not exceed 120, unless a rigorous analysis has
been carried out in accordance with Clauses 6.4, 6.5 or 6.6 and the column is designed in
accordance with Clause 10.2.3.
Where the forces and moments acting on a column have been obtained from a linear elastic
analysis, as specified in Clause 6.2, the influence of slenderness shall be taken into account
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using a radius of gyration (r) specified in Clause 10.5.2 and an effective length (Le), in
accordance with Clause 10.5.3.
10.5.2 Radius of gyration
The radius of gyration (r) shall be calculated for the gross concrete cross-section.
NOTE: For a rectangular cross-section, r may be taken as 0.3D, where D is the overall dimension
in the direction in which stability is being considered and for a circular cross-section, r may be
taken as 0.25D.
10.5.3 Effective length of a column
The effective length of a column (Le) shall be taken as kLu, where the effective length factor
(k) is determined from Figure 10.5.3(A) for columns with simple end restraints, or more
generally from Figure 10.5.3(B) or 10.5.3(C), as appropriate.
The end restraint coefficients (1 and 2) shall be determined—
(a) where the column ends at a footing, in accordance with Clause 10.5.5;
(b) for all other structures, including non-rectangular framed structures or structures
where the axial forces in the restraining members are large, in accordance with
Clause 10.5.4.
Alternatively, the effective length of a column may be determined from the elastic critical
buckling load of the frame, as calculated by analysis.
Br ac e d c o lum n Un br ac e d c o lum n
Buckled
shape
Ef fe c t i ve l e n g t h
0.70 0.8 5 1.0 0 1.3 0 1. 20 2. 20 2. 20
fac tor (k)
FIGURE 10.5.3(A) EFFECTIVE LENGTH FACTOR (k) FOR COLUMNS WITH SIMPLE
END RESTRAINTS
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∞
50
0.
10
95
6
0.
90
3
0.
2
85
EN D RESTR AINT COEFFICIENT γ 1
γ2
1. 5
0.
1. 2
80
1.0 k
0.
75
γ1
0.
70
0. 5
0.
65
0.
60
0.
55
0 ∞
0 0. 5 1.0 1. 2 1. 5 2 3 4 6 10 5 0
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∞
50
4
3
10
2.
5
6
2.
0
4
1.
3
8
1.
6
2
EN D RESTR AINT COEFFICIENT γ 1
γ2
1.
5
1. 5
1.
4
1. 2 k
1.0
1.
3
1.
25
γ1
1.
20
1.
0. 5
15
1.
10
1.
05
0 ∞
0 0. 5 1.0 1. 2 1. 5 2 3 4 6 10 5 0
TABLE 10.5.4
FIXITY FACTOR ()
Fixity factor ( )
Fixity conditions at far end
of a column, beam or slab Beam or slab or both, Beam or slab or both,
in a braced frame in an unbraced frame
Pinned 1.5 0.5
Rigidly connected to a column 1.0 1.0
Fixed 2.0 0.67
(c) The distribution of stress in the concrete and the steel is determined using a stress-
strain relationship determined from Clauses 3.1.4 and 3.2.3 respectively (see Note 1).
(d) The strain in compressive reinforcement does not exceed 0.003.
(e) Where the neutral axis lies outside of the cross-section, consideration is given to the
effect on strength of spalling of the cover concrete.
NOTE: If a curvilinear stress-strain relationship is used then—
(a) Clause 3.1.4 places a limit on the value of the maximum concrete stress; and
(b) the strain in the extreme fibre may be adjusted to obtain the maximum bending strength for a
given axial load.
The provisions in Items (c) and (d) above shall not be used to assess the flexural strength at
plastic hinge zones for seismic design (see Clause 10.2.4.3).
Columns subject to axial force with bending moments about each principal axis may take
into account the concessions given in Clauses 10.6.3 and 10.6.4.
10.6.2 Strength of cross-sections calculated using the rectangular stress block
10.6.2.1 General
This Clause shall not apply to the assessment of flexural strength at plastic hinge zones for
seismic design.
It shall be permissible to represent the strength of a cross-section in combined bending and
compression using a strength interaction diagram as shown in Figure 10.6.2.1 defined as
given in Clauses 10.6.2.2 to 10.6.2.5.
Decompression
p o int (Cl au s e 10.6. 2. 3)
A XIAL LOAD
B a l an c e d
p o int
C l au s e 10.6. 2. 5
Pure b e n d in g
p o int (Cl au s e 8 .1)
M O M ENT
0.1D
b 0. 2 D
0.1b
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0. 2 b
M 2*
(i) 0.4 L ; and
M 1* M 2*
φN u o
Re g i o n w h ere t h e d e s i g n ac t i o n
ef fe c t s of c o m b in e d a x i al for c e
DESIG N A XIAL FORCE
an d b e n d in g o n a se c t i o n
0.75φN u o require c o nfinement to the c ore
(φM u , φN u)
φN u
(0.6φM u , φN u)
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φ 0.3 A g f ’c
0.6φM u φM u o
DESIG N M O M ENT
M 1*
Special confinement
1.2D region
0.6φM u
0.6φM u
Special confinement
1.2D region
M *2
D
0.6φM u
A
i 1
b.fit f sy.f sin
. . . 10.7.3.3(2)
fr
ds s
where
Ab.fit = cross-sectional area of one leg of the fitment
fsy.f = yield stress of the reinforcement used as fitment (not greater than 500 MPa)
= angle between the tie leg and the confinement plane
m = number of fitment legs crossing the confinement plane
ds = overall dimension measured between centre-lines of the outermost fitments
s = centre to centre spacing of fitments along the column
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where
Ac = cross-sectional area bounded by the centre-line of the outermost fitments
n = number of laterally restrained longitudinal bars [see Clause 10.7.4.2(a)]
w = average clear spacing between adjacent tied longitudinal bars
bc = core dimension measured between the centre-lines of the outermost
fitments measured across the width of the section
dc = core dimension measured between the centre-lines of the outermost
fitments measured through the depth of the section
(b) For circular sections:
2
s
k e 1 . . . 10.7.3.3(4)
2d s
Alternatively, for rectangular or circular columns, the effective confining pressure applied
to the core of a column may be calculated as follows:
fr.eff = 0.5kes fsy.f . . . 10.7.3.3(5)
where
s = volumetric ratio of the fitments relative to the volume of the core calculated
as
Ab.fit total perimeter of fitments crossing the section
s
Ac s
bc
fr A b.f i t f s y.f
ds
fr A b.f i t f s y.f
(a) (b)
bc y
Y
A b.f i t f s y.f
dc f r.y y
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A b.f i t f s y.f x
fr Y
bc
A b.f i t f s y.f (s in θ)
2 A b.f i t f s y.f (s in θ)
fr = X X
bcs
f r. x x A b.f i t f s y.f
f r = m in.(f r. x x , f r.y y)
(c) (d)
where
n = number of laterally restrained longitudinal bars [see Clause 10.7.4.2(a)]
(b) For circular sections:
100 Ab. fit f sy.f
. . . 10.7.3.4(2)
d s f c
10.7.4 Restraint of longitudinal reinforcement
10.7.4.1 General requirements
The following longitudinal bars in columns shall be laterally restrained in accordance with
Clause 10.7.4.2:
(a) Single bars—
(i) each corner bar;
(ii) all bars, where bars are spaced at centres of more than 150 mm; and
(iii) at least every alternate bar, where bars are spaced at 150 mm or less.
Where N* 0.5 Nu the requirements of Items (ii) and (iii) do not apply.
(b) Bundled bars, each bundle of longitudinal bars.
10.7.4.2 Lateral restraint
Lateral restraint shall be deemed to be provided if the longitudinal reinforcement is placed
within and in contact with—
(a) a non-circular fitment (see Figure 10.7.4.2)—
(i) at a bend in the fitment, where the bend has an included angle of 135° or less;
or
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TABLE 10.7.4.3
BAR DIAMETERS FOR FITMENTS AND HELICES
Longitudinal bar diameter Minimum bar diameter
of fitment and helix
mm mm
Single bars up to 20 6
Single bars 24 to 28 10
Single bars 28 to 36 12
Single bars 40 16
Bundled bars 12
where
f ce = expected compressive strength of the concrete (may be taken as 1.3 f c )
fsy.f = yield strength of the reinforcement used as fitments
(b) Where rectangular fitments are used, the total cross-sectional area of the ties (Asv),
including supplementary cross-ties, shall be not less than—
Asv 0.055sy1 f ce f sy.f 0.006 ; and . . . 10.7.6.2.2(2)
s 0.006 . . . 10.7.6.2.2(3)
where
s = centre-to-centre spacing of ties along the longitudinal axis of the
member
y1 = core dimension of a closed rectangular tie in the direction under
consideration, as illustrated in Figure 10.7.6.4
Where N* < 0.2Nuo at least half the reinforcement specified in Items (a) and (b) shall be
provided.
10.7.6.2.3 Minimum lateral reinforcement
The volumetric ratio of the lateral reinforcement (ρs) shall be not less than 0.0025 for
circular columns and 0.003 for rectangular columns in locations where:
N* > 0.2Nuo and category BEDC-4 applies
N* > 0.2Nuo and category BEDC-3 applies and µ 3
10.7.6.3 Spacing of lateral reinforcement at plastic hinge
The spacing of lateral reinforcement shall satisfy the following:
(a) The spacing (s) of the lateral (confinement) reinforcement shall not exceed the lesser
of—
s = 0.2Dc and . . . 10.7.6.3(1)
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s = 6dbl . . . 10.7.6.3(2)
where
Dc = depth of the rectangular column in the direction under consideration or
the diameter of circular columns
dbl = diameter of longitudinal reinforcement steel
(b) Internal fitments shall be provided in non-circular columns so that the maximum
spacing of laterally restrained longitudinal bars shall not exceed 300 mm.
10.7.6.4 Extension of plastic hinge lateral reinforcement
Where plastic hinge lateral reinforcement is provided, it shall be extended as follows:
(a) The lateral (confinement) reinforcement shall extend from the top and bottom of
framed columns, or from the base of cantilever columns, for a distance equal to the
cross-section dimension in the direction under consideration or the region where the
moment exceeds 80% of the critical moment (M1 or M2, as shown in Figure 10.7.6.4),
whichever is greater.
(b) In pile-type pier columns, see Figure 10.7.6.4 for plastic hinge zones. The lateral
reinforcement shall be extended above and below the critical moment region (M1 or
M2, as shown in Figure 10.7.6.4) for at least the cross-section dimension in the
direction under consideration or the region where the moment exceeds 80% of the
maximum moment at the support, whichever is greater.
(c) The lateral reinforcement required within the predicted and plastic hinge zones shall
extend into the footing, pile cap or superstructure, as applicable, for a length not less
than half the maximum dimension of the column or 400 mm, whichever is greater
(see Figure 10.7.6.4).
≥ t h e l ar g er of 4 0 0 m m
M1 ma x. and ½ pile d i ameter
≥ t h e l ar g er of p il e
Bending d i a m e te r a n d r e g i o n w i t h
m o m e nt m o m e nt ≥ 8 0% of M 1 m a x
S e i s m i c c o nfi n m e nt
8 0%
of M 1 m a x .
Lo n g i t u d i n a l b ar s
L of p il e
N o r m a l c o nfi n e m e nt
C
S e i s m i c c o nfi n e m e nt
8 0% of M 2 m a x .
Bending
m o m e nt ≥ t h e l ar g er of p il e
d i a m e te r a n d r e g i o n w i t h
m o m e nt ≥ 8 0% of M 1 m a x
M2 max.
≥ t h e l ar g er of p il e
d i ameter and with
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m o m e nt ≥ 8 0% of M 2 m a x .
8 0% of M 2 m a x .
N o r m a l c o nfi n e m e nt
10.7.6.5 Splicing and anchoring of lateral reinforcement within plastic hinge zones
The following applies for splicing and anchoring of lateral (confinement) reinforcement:
(a) Splicing of helices shall be by welding or mechanical splicing in accordance with
Clause 13.2.6.
(b) Closed ties shall not be anchored by welding to the longitudinal reinforcement.
Closed ties shall end with 135° hooks in accordance with Clause 13.1.2.7.
(c) Internal fitments used as seismic confinement in predicted plastic hinge zones in
columns with rectangular cross-sections shall comprise a straight bar with a 135°
seismic hook at one end and fully anchored at the other end.
indeterminate structures.
11.1 GENERAL
This Section applies to the following:
(a) Braced walls (as defined in Clause 11.3) that are subject to in-plane load effects,
which shall be designed in accordance with Clauses 11.2 to 11.7.
(b) Braced walls that are subject to simultaneous in-plane and out-of-plane load effects
and unbraced walls, which shall be designed in accordance with Section 9, Section 10
and Section 11, as appropriate.
Where the maximum compressive stress at the mid-height section of a wall due to
factored in-plane bending and axial forces does not exceed the lesser of 0.03 f c and
2 MPa, the wall may be designed as a slab in accordance with Section 9, provided—
(i) second-order deflections due to in-plane loads and long-term effects are
considered in the calculation of bending moments; and
(ii) the ratio of effective height to thickness does not exceed 50.
(b) 2.5% of the total vertical load the wall is designed to carry at the level of lateral
support, but not less than 2 kN per metre length of wall.
L1
k where Hw > L1 . . . 11.4(3)
2H w
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Walls supported laterally on four sides that contain one or more openings shall be
designed as follows:
(i) If the total area of the openings is less than 1/10 of the area of the wall and the
height of any opening, not vertically one above the other, is less than 1/3 of the
height of the wall, then the effect of the openings may be ignored.
(ii) In other cases—
(A) the area of the wall between the support and the opening shall be
designed as supported on three sides; and
(B) the area between the openings shall be designed as supported on two
sides.
NOTE: An intersecting wall with a minimum length of 0.2H w may be considered a lateral
restraint.
where
= 0.6
Nu = tw 1.2e 2ea 0.6 f c . . . 11.5(2)
The maximum centre-to-centre spacing of parallel bars shall be the lesser of 2.5tw and
300 mm.
The vertical and horizontal reinforcement shall be provided in two grids, one near each face
of the wall under any of the following conditions:
(a) Walls greater than 200 mm thick.
(b) Any part of a wall structure where tension exceeds the tensile capacity of the concrete
under the design ultimate loads.
(c) Walls designed for two-way buckling [based on Clause 11.4(b) or Clause 11.4(c)].
(d) Wall-type piers for earthquake resistance.
11.7.4 Restraint of vertical reinforcement
For walls designed as columns in accordance with Section 10, the restraint provisions of
Clause 10.7.4 shall not apply if either—
(a) the vertical reinforcement is not used as compressive reinforcement; or
(b) the vertical reinforcement ratio is not greater than 0.02, and a minimum horizontal
reinforcement ratio of 0.0035 is provided.
NOTE: For walls greater than 500 mm thick, the minimum reinforcement required near each
surface may be calculated using 250 mm for tw .
2tw En d re g i o n s 2tw
tw
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15 0 15 0 2tw ma x. 2tw ma x.
max. max.
12.2 DESIGN
12.2.1 Design for strength
The design for strength shall be carried out using one of the following:
(a) Linear elastic stress analysis and the checking procedure given in Clause 2.3.3.
(b) Strut-and-tie analysis, and the checking procedure given in Clause 2.3.4.
(c) Non-linear stress analysis and the checking procedure given in Clause 2.3.6.
The value of the capacity stress and strength reduction factor shall be determined according
to Clauses 2.3.3, 2.3.4 and 2.3.6 as appropriate, for the analysis and checking procedure
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adopted.
12.2.2 Design for serviceability
Design for serviceability shall be in accordance with Clause 2.4 and Clause 12.7.
For Type II models, the force carried by the secondary struts shall be within the limits
0 Tw P, where Tw is the vertical component of the force carried by the secondary struts
and P is defined in Figure 12.3.2.
a P P
w
z d z
D
θ θ
T T
P P
(a) S tr ut- an d -t i e (b) S im p lifi e d
T YPE I
a P
P
a /2 a /2
w
Tw
z d z
D
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T T
P P
(a) S tr ut- an d -t i e (b) S im p lifi e d
T YPE II
a P P
w
Tw
D d
z z
θ θ
T T
P P
(a) S tr ut- an d -t i e (b) S im p lifi e d
T YPE III
are cast into a member at intermediate locations (see Figure 12.6.7), tensile zones can
develop behind the anchorage with tensile stresses parallel to the tendons, which
depend on the following:
(i) The magnitude of the anchored prestress forces.
(ii) The magnitude of the compressive stress in the longitudinal direction.
(iii) The ratio of the area of the anchorage to the total cross-sectional area of the
prestressed member.
Special reinforcement, designed to resist from 20% to 50% of the prestress force in
the tendon shall be provided to control these tensile stresses and shall be detailed as
shown in Figure 12.6.7. Such reinforcement shall extend at least over a length of 2D
as shown in Figure 12.6.7 and, have sufficient length to develop the yield stress (fsy)
of the reinforcing bar at the anchorage.
(c) External anchorages Where external anchorages (i.e. anchorages located on a
protruding bracket on the member) are used, reinforcement in addition to that
provided to resist the bursting tensile forces shall be designed, where applicable to—
(i) resist tension caused by curvature of tendons;
(ii) provide a shear connection to the main member and cater for the distribution of
the prestress force into the main member;
(iii) resist the forces as described in Item (b); and
(iv) resist tension caused by local eccentricity of prestress force.
S p e c i al B ur st i n g
r e i nfor c e m e nt reinforc ement
D = D e pt h of
m e m b er
C e nt r i o d
of te n d o n
L s y.t ≥ D L s y.t ≥ D
A n c h or ag e
decompression does not exceed the limits given by Item (a), or (b) as appropriate.
where
A2 = largest area of the supporting surface that is geometrically similar to and
concentric with A1
A1 = a bearing area
Where bearing areas are subject to high edge loading by the bearing plate, the design
bearing stress shall be not greater than 0.7 times the value specified above.
In the case of a bearing surface where the supporting structure is sloped or stepped, it shall
be permissible to take A2 as the area of the base of the largest frustum of a right pyramid or
cone—
(a) having for its opposite end the bearing area A1;
(b) having side slopes of 2 transversely to 1 longitudinally, with respect to the direction
of the load; and
(c) contained wholly within the supporting structure.
NOTE: This Clause is not applicable to the design of nodes within a strut-and-tie model.
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where
k1 = 1.3 for a horizontal bar with more than 300 mm of concrete cast below the bar;
or
= 1.0
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C1
a a
c c
C1
(a) S tr ai g ht bar s (b) C o g g e d or h o o ke d bar s (c) Lo o p e d bar s
c d = m in (a /2, c 1, c) c d = m in (a /2, c 1) cd = c
(i) N ar r ow e l e m e nt s o r m e m b er s (e.g. b e a m we b s a n d c o l u m n s)
a a
c c
a
a
L s y.t L s y.t
db
(i i i) Pl a n ar v i ew of s t ag g er e d d eve l o p m e nt l e n g t h s of e q u i - s p a c e d b ar s
www.standards.org.au
TABLE 13.1.2.3
VALUES OF K FOR TYPICAL ARRANGEMENTS OF TRANSVERSE REINFORCEMENT FOR DIFFERENT MEMBER TYPES
Member type Examples of potential splitting cracks at a tensile face nf n bs K (see Note 2)
Circular column
1 1 0.10
A t r = A b.f i t
Rectangular
column
n f = 2, n b s = 2 n f = 2, n b s = 3
K= 0.10 K= 0.0 8 3 1 1
A t r = A b.f i t
Beam
163
0.05 K 0.10
n f = 2, n b s = 4
A t r = A b.f i t 1 1
K= 0.075
Slab or wall
(with fitments) n f= n bs
A t r = A b.f i t 1 1
K= 0.10
Slab or wall
(without fitments) A tr
1 per main 0.05
0
bar spacing (see Note 3)
LEGEND:
n bs = total number of bars being anchored at the location under consideration
n f = numbered of anchored bars at the location under consideration adjacent to, and restrained by, a transverse bar or fitment
Standards Australia
NOTES:
1 Fitments are a type of transverse reinforcement.
AS 5100.5:2017
2 The same value of K shall apply to all of the longitudinal bars being either anchored or lap spliced, i.e. it is a weighted average value.
3 To be effective, the transverse reinforcement shall be located between the longitudinal bars and the concrete tensile face as shown, otherwise K = 0.
AS 5100.5:2017 164
0. 5L s y.t
or 0. 5L s t
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0. 5L s y.t
or 0. 5L s t
(a) S t an d ar d h o o k (b) S t an d ar d c o g
required for the largest bar within the bundle increased by—
(a) for a 3-bar bundle ......................................................................................... 20%; and
(b) for a 4-bar bundle ................................................................................................ 33%.
13.1.8 Development length of welded plain or deformed mesh in tension
13.1.8.1 Development length to develop yield strength
The development length (Lsy.t) of welded plain or deformed mesh, measured from the
critical section to the end of the bar or wire, shall be calculated in accordance with
Clause 13.1.8.2, Clause 13.1.8.3 or Clause 13.1.8.4, as appropriate.
13.1.8.2 Two or more cross-bars within development length
The yield strength of deformed bars of welded mesh shall be deemed to be developed by
embedding at least 2 cross-bars spaced at not less than 50 mm within the development
length, with the first cross-bar located not less than 50 mm from the critical section. For
plain bars, the 2 cross-bars shall be spaced at not less than 100 mm within the development
length.
13.1.8.3 One cross-bar within development length
When only one cross-bar is located within the development length, the minimum length
measured from the critical section to the outermost cross-bar shall be not less than Lsy.tb
calculated from—
Ab f sy
Lsy.tb 3.25 . . . 13.1.8.3
sm f c
but not less than 150 mm for plain mesh and not less than 100 mm for deformed mesh,
where
Ab = area of the individual bar being developed
s m = spacing of bars being developed
13.1.8.4 No cross-bars within development length
When no cross-bars are located within the development length, the development length of
welded mesh shall be determined in accordance with Clauses 13.1.2 and 13.1.3, as
appropriate.
13.1.8.5 Development length to develop less than the yield strength
The development length (Lst ) to develop a tensile stress ( st ) less than the yield strength (fsy)
shall be calculated from the development length determined from Clause 13.1.8.3 or
Clause 13.1.8.4, using the following equation:
st
Lst Lsy.tb . . . 13.1.8.5
f sy
Lst shall be not less than 150 mm for plain mesh and not less than 100 mm for deformed
mesh.
(c) Splicing of reinforcement shall take into account the requirements of Clause 17.3.3
regarding the placement of concrete.
(d) Splices required in bars in tension-tie members shall be made only by welding or
mechanical means.
(e) Lapped splices shall not be used for bars in compression or tension with diameter
larger than 40 mm.
(f) Welding of reinforcing bars shall not be made within 3db from that part of a bar that
has been bent and re-straightened.
13.2.2 Lapped splices for bars in tension
In wide elements or members (e.g. flanges, band beams, slabs, walls and blade columns),
where the bars being lapped are in the plane of the element or member, the tensile lap
length (Lsy.t.lap) for either contact or non-contact splices shall be calculated from the
following equation:
Lsy.t.lap k7 Lsy.t 29k1d b . . . 13.2.2
where
Lsy.t is calculated in accordance with Clause 13.1.2.1. (In the determination of Lsy.t for
use in Equation 13.2.2, the lower limit of 29k1 db in Equation 13.1.2.2 does not apply);
and
k7 shall be taken as 1.25 (unless As provided is at least twice As required and not more
than half of the reinforcement at the section is spliced, in which case k7 may be taken
as 1.0).
In narrow elements or members (such as beam webs and columns), the tensile lap length
(Lsy.t.lap) shall be not less than the larger of 29k1db , k7 Lsy.t and Lsy.t + 1.5sb , where sb is the
clear distance between bars of the lapped splice as shown in Figure 13.2.2. Provided sb does
not exceed 3db , then sb may be taken as zero for calculating Lsy.t.lap.
PL ANAR VIE W
(S e e N ote 1)
sL a sb
db
L s y.t . l a p c d = m in (a /2,c)
≥ 0.3L s y.t . l a p
sL
sb
L s y.t . l a p
c d = m in (a /2,c)
(ii) 5 0% st ag g ere d s p li c e s
NOTES:
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1 For the purposes of determining c d , dimension a shall be taken equal to (s L d b ) irrespective of the value
of s b .
2 For the purposes of determining c d , dimension a shall be taken equal to 2s L irrespective of the value of s b .
s2 s2
s1 s1
Welded or mechanical splices for the jointing or anchorage of reinforcing steel shall
possess an ultimate tensile strength exceeding 1.25 fsy of the bar.
When control of cracking or vertical deflection are relevant serviceability design criteria,
the potentially detrimental effects of excessive longitudinal slip between spliced Ductility
Class N bars and a proprietary mechanical connector shall be considered if tests show the
effective slip in the assemblage could exceed 0.1 mm at a tensile stress of 300 MPa. The
effective slip shall be taken as the overall deformation of a spliced pair of reinforcing bars,
measured over a gauge length of 12db , less the elongation of the bars assuming they are
unspliced over the same gauge length.
Welded splices shall be in accordance with AS/NZS 1554.3.
Mechanical splices of longitudinal reinforcement used in potential plastic hinge zones shall
be tested to prove the capability of the splice to sustain at least the ultimate tensile strength
of the bar.
TABLE 13.3.2.1
MINIMUM TRANSMISSION LENGTH
FOR PRETENSIONED TENDONS
p.ef = effective stress in the tendon after allowing for all losses
pu and p.ef are in megapascals.
Embedment less than the development length shall be permitted at a section of a member,
provided the design stress in the strand at that section does not exceed the values obtained
from the bi-linear relationship defined by this Clause and Clause 13.3.2.1.
The development length of de-bonded strand shall be taken to be 2Lp where the design
includes tension in accordance with Clauses 8.6.2 and 9.4.2 in the development length.
13.3.2.3 Development length of pretensioned wire
Pretensioned indented and crimped wire tendons shall be bonded beyond the critical section
for a length sufficient to develop the design stress in the wire but not less than 2.25 times
the value for the transmission length in Table 13.3.2.1 as appropriate.
13.3.2.4 Development length of untensioned strand or wire
Where strand or wire is untensioned, the development length shall be taken as not less than
2.5 times the value of the appropriate transmission length of a stressed tendon given in
Table 13.3.2.1 for a tendon stressed to the tensile strength (fpb) in Table 3.3.1.
13.3.3 Stress development in post-tensioned tendons by anchorages
Anchorages for tendons shall be capable of developing in the tendon the minimum tensile
strength (fpb).
In addition, anchorages for unbonded tendons shall be capable of sustaining cyclic loading
conditions.
14.1 JOINTS
14.1.1 General
A joint in a structure or member shall be designed and constructed so the load-carrying
capacity and serviceability of the structure or member is maintained while serving its
intended function. Joints shall be for construction purposes (construction joint) or to control
movement (movement joint), as appropriate.
14.1.2 Construction joints
14.1.2.1 General
Construction joints shall be designed and installed to satisfy intended construction practice
for the specific application. Construction joints shall be designed to produce a well-bonded
interface between hardened concrete and freshly placed concrete.
14.1.2.2 Joint spacing
Construction joints shall be located to facilitate the placement of concrete in accordance
with Clause 17.3.3 and to meet concrete placement restrictions and finishing requirements.
They shall be located in regions of minimal shear force and, where possible, in unobtrusive
locations. The spacing shall be determined by the rate of concrete placement and finishing
on site or as a result of any unplanned interruption to placement operations.
Where an interruption to the placing of concrete occurs such that the requirements of
Clause 17.3.3(c) or Clause 17.3.3(d) or Clause 17.3.3(e) cannot be fulfilled, a construction
joint shall be made at an appropriate location.
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14.3 FIXINGS
Fixings, including holding-down bolts, inserts and ferrules, shall comply with the
following:
(a) A fixing shall be designed to transmit all forces, acting or likely to act on it.
(b) Forces on fixings used for lifting purposes shall include an impact factor in assessing
the load.
(c) Fixings shall be designed to yield before ultimate failure in the event of overload.
(d) The anchorage of any fixings shall be designed in accordance with Section 13, as
appropriate. The design strength of this anchorage shall be taken as times the
ultimate strength, where = 0.6. In the case of shallow anchorages, cone-type failure
in the concrete surrounding the fixing shall be investigated taking into account edge
distance, spacing, the effect of reinforcement, if any, and concrete strength at time of
loading.
(e) In the absence of calculations, the strength of a fixing shall be determined by load
testing of a prototype to failure in accordance with Paragraph A4, Appendix A. The
design strength of the fixing shall be taken as times the ultimate strength where the
ultimate strength is taken as the average failure load divided by the appropriate factor
given in Table A4.3, Appendix A and = 0.6.
(f) The spacing between, and cover to, fixings shall be in accordance with Clause 14.2.3.
The cover for fixings shall be in accordance with Section 4. The cover for fire
resistance shall be in accordance with Section 5.
15.1 GENERAL
Plain concrete shall be used only for members in which cracking will not induce collapse.
The provisions of this Section apply to—
(a) plain concrete pedestals, provided the unsupported height of the member is not
greater than three times the least lateral dimension;
(b) plain concrete footings supported by the ground;
(c) gravity retaining walls; and
(d) bored piles.
The value of throughout this Section shall be determined from Table 2.3.2.
15.2 DESIGN
15.2.1 Basic principles of strength design
Members shall be designed in accordance with the following:
(a) Design of members for flexure shall be based on a linear stress-strain relationship in
both tension and compression.
NOTE: The tensile strength of concrete may be considered in the design.
(b) No tensile strength shall be assigned to reinforcement that may be present.
(c) Plain concrete members shall comply with the appropriate provisions of Section 4.
15.2.2 Section properties
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= 0.1uD1 2 / h f c 0.2uD f c
In the absence of more exact calculations, members subject to combined bending and axial
load shall be designed so that the maximum compressive stress under the design actions
does not exceed 0.45 f c and the maximum tensile stress does not exceed f ct.f . For a
member in combined bending and axial compression, the minimum eccentricity shall be
taken as 0.1a, where a is the cross-sectional dimension in the direction being considered.
The unsupported length of a plain concrete member in combined bending and compression
shall be not greater than 3 times the least lateral dimension.
16.1 GENERAL
This Section shall apply where steel fibres are used to improve the performance and
capacity of reinforced and prestressed concrete structures.
The design of steel fibre reinforced concrete (SFRC) at both the ultimate and serviceability
limit states shall be based on the stress ( ) ≠ strain () relationships for SFRC as specified
in Clause 16.3.3.
NOTE: When using brittle fibres that rely on a fibre pullout failure mechanism to obtain member
ductility, care is required for cases where a significant number of fibres fracture or where fibres
result in local crushing of the concrete due to the local forces imposed on the matrix by the fibres.
Fibre fracture may occur where the bond between the fibre and the matrix is high, and this is
more likely in a high strength concrete combined with fibres of high bond capacity and of lower
strength steels. In assessing the suitability of a given fibre for a given application, bond-strength
gain in time and the resulting potential loss of ductility should be considered.
Steel fibres shall not be relied upon for strength under reverse cyclic loading, unless supported by
test data.
Steel fibres shall not be relied upon at constructions joints for either serviceability or
strength requirements.
Design procedures in this Section are for steel-fibre-reinforced concrete with a softening
classification only (see Figure 16.3.3.1). Hardening SFRC and the use of synthetic fibres is
beyond the scope of this Standard.
16.2 DEFINITIONS
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ƒc t
ƒ0.5
ƒ 1. 5
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ε
0 ε cr
COD
0 0. 5 m m 1. 5 m m
σ
Cr ac k l o c aliz at i o n
ƒ c t ≥ 1.1 ƒ c t m
ƒc t m
Cr ac k for m at i o n
ε
0 ε cr
COD
0 ≥ 0.3 m m
(c) The specimen shall be connected to the testing machine in such a manner that the
machine does not apply a load to the specimen during the process of tightening of the
grips and prior to testing.
(d) One end of the specimen shall be connected to the testing machine through a
universal joint such that no moment is applied to the end of the specimen.
(e) Displacement measurements shall be taken on each of the four sides with the COD
taken as the average of these measurements.
(f) A minimum of 12 specimens shall be tested.
(g) Tests where the failure of the specimen is outside of the testing region, or where the
results are influenced by the test specimen boundaries, shall be retested.
(h) The characteristic values of the tensile strength f0.5 and f1.5, corresponding to CODs of
0.5 mm and 1.5 mm, respectively, shall be determined statistically as the
95 percentile confidence value assuming the population is normally distributed.
(i) The mean values of f0.5m and f1.5m, corresponding to CODs of 0.5 mm and 1.5 mm,
respectively, shall be determined statistically as the 50th percentile confidence value
assuming the population is normally distributed.
The stress results obtained from the test shall be multiplied by the three-dimensional
orientation factor k1, where—
1
k1 1 . . . 16.3.3.7
0.94 0.6lf / b
and lf is the length of the steel fibre and b is taken as the average of the width and depth of
the specimen taken at the critical section.
NOTES:
1 The factor k1 removes the influence of the boundaries on the fibre distribution and converts
the results of the test to a state where the fibres can be considered to be randomly orientated
in three-dimensional space.
2 Testing should be undertaken in a laboratory accredited by the National Association of
Testing Laboratories (NATA).
Univer sal
j o i nt
≥125
≥ 25
125
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5
R 14
125
215
Ep ox y g lu e
≥125
(o ptional)
All dimensions ±5 mm
where
b = width of the specimen, in millimetres
hsp = distance between tip of the notch and top of cross-section, in millimetres
L = span
FRj = load recorded at CMODj (see Figure 16.3.3.9)
NOTE: Testing should be undertaken in a laboratory accredited by the National
Association of Testing Laboratories (NATA).
FL
F R .1
FR.2
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FR.3
F R .4
CMOD (m m)
C
0. OD
C
M
M
05
O
D1
D 4
2
3
L
=
=
=
0.
3.
1.
2.
5
5
5
5
16.4.2 Strength of beams in bending and combined bending and axial force
Calculations for strength of cross-sections in bending shall incorporate equilibrium and
strain-compatibility considerations and be consistent with the following assumptions:
(a) Plane sections normal to the axis shall remain plane after bending.
(b) The stress in the SFRC in that part of the cross-section in tension shall be taken to be
f1.5 , where f1.5 is the characteristic residual tensile stress determined in accordance
with Clause 16.3.3.3.
(c) The distribution of compressive stress shall be determined from a stress-strain
relationship for the concrete in accordance with Clause 3.1.4.
The strength of a section in bending, or in combined bending and axial force, shall be
determined using rectangular stress blocks for the concrete in compression and concrete in
tension, as shown in Figure 16.4.2.
α 2 f c´
Cs
γdn Cc
dn
N. A .
d
D
f 1.´ 5 Tf
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Ts
α 2 f c´
Cs
γdn Cc
dn
d N. A .
do
D
f 1.´ 5 Tf
Ts
θv = angle between the axis of the concrete compression strut and the longitudinal
axis of the member and shall be taken as not less than 38°
16.4.4.3 Minimum shear reinforcement
The minimum contribution from the total of the transverse steel reinforcement and fibres
shall satisfy the following:
0.6bv d o
16.4.5 Design for serviceability limit states
16.4.5.1 General
When an SRFC cross-section is uncracked, the full cross-section shall be assumed to be
active and both concrete and steel assumed to be elastic in tension as well as in
compression.
When an SRFC cross-section is cracked, the SFRC shall be assumed to be elastic in
compression, and capable of sustaining a tensile stress equal to 1.1 f1.5 .
e/D = ratio of the eccentricity of the prestressing force on the cross-section (e)
measured from the centroidal axis of the uncracked section to the overall
depth of the cross-section in the plane of bending (D)
σcp = average intensity of the effective prestress (Pe/Ag)
16.4.5.4 Deflection control
16.4.5.4.1 General
The deflection of an SFRC member shall be calculated using the procedures outlined in
Clauses 16.4.5.4.2 and 16.4.5.4.3. Allowance shall be made for the expected load history,
the expected construction procedure and any anticipated deflections resulting from
deformation of forms or settlement of props.
16.4.5.4.2 Short-term deflection
The short-term deflections due to external loads and prestressing, which occur immediately
on their application, shall be calculated using the value of Ecj determined in accordance
with Clause 3.1.2 and the value of the effective second moment of area of the member (Ief).
The value of Ief may be determined from the values of Ief at nominated cross-sections as
follows:
(a) For a simply supported span, the value at midspan.
(b) In a continuous beam—
(i) for an interior span, half the midspan value plus one quarter of each support
value; or
(ii) for an end span, half the midspan value plus half the value at the continuous
support.
(c) For a cantilever, the value at the support.
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For the purpose of the above determinations, the value of Ief at each of the cross-sections
nominated in Items (a) to (c) above shall be obtained from the instantaneous curvature
i M s* Ecj I ef calculated as the slope of the strain diagram in Figure 16.4.5.4.2(b) and
obtained by satisfying the requirements for rotational and horizontal equilibrium of the
stress distribution in Figure 16.4.5.4.2(c).
εo σ o= E cjε o
d n /3
dn Cc
(d+ d n)/2
D d d
ε s = ε o (d - d n)/d n
A st σ s= E sε s
1.1 f 1.
´5
16.5 DURABILITY
The minimum concrete grade and cover for SFRC in exposure classifications A, B1 and B2
shall be as for concrete without fibres and shall apply to the steel reinforcement only. SFRC
shall not be used in exposure classification C1 or C2.
NOTES:
1 Steel fibres do not require concrete cover as specified for steel reinforcement in Clause 4.14.
2 SFRC may not be suitable in some exposure classification U environments.
16.6 FIRE
The structural performance of SFRC for fire shall be determined in accordance with
Section 5 of this Standard.
The material properties for SFRC shall be as specified for concrete in Clause 5.4.1 except
that the characteristic residual tensile stress of SFRC at elevated temperatures ( f1.5θ ) shall
be either—
(a) taken as f1.5θ k θ1 f1.5 where kθ1 is given in Table 16.6; or
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TABLE 16.6
ELEVATED TEMPERATURE COEFFICIENT
FOR RESIDUAL TENSILE STRESS OF SFRC
Temperature of SFRC
0 100 500 700 1200
°C
k θ1 1.0 1.0 0.6 0.1 0.0
NOTE: Linear interpolation between values.
TABLE 16.7.3
PRE-CONSTRUCTION TESTS
Material Inspection/Test Purpose
Steel fibres Check delivery note Verify that the delivery is in
accordance with the order, and is
shipped from the correct source
Check CE label Verify that the fibres have the
correct CE-label which matches
the corresponding Certificate of
Conformity
Steel fibre content in the fresh Testing according to EN 14721 Conformity with the target dosage
concrete and Clause 16.7.5 on the basis of
Verify homogeneous distribution
9 samples
of the steel fibres in the mix
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Steel fibre concrete performance Check limit of proportionality, and Verify that the performance is in
post-crack flexural strength in accordance to the specification
accordance to EN 14651 on a
The performance level serves as
minimum of 12 beams
the reference for continuous
production control
NOTE: The strength of the population may be treated as normally distributed and the characteristic strength
determined in accordance with ISO 12491. A confidence level of 75% shall be used such that 95% of the
population exceeds the characteristic value. For a sample of 12 specimens, the characteristic strength may be
calculated from the mean strength using characteristic strength = mean strength (1 1.84 COV). The
coefficient of variation (COV as a percentage) shall not exceed 25%.
TABLE 16.7.4
ROUTINE PRODUCTION CONTROL
Subject Inspection/Test Purpose Frequency
Equipment inspection
Automatic dosing Visual inspection Assure correct functioning Once per production day
equipment for steel of dosing device
fibres
Control of accuracy Avoid improper fibre On installation
dosage
Periodically
In case of doubt
Materials inspection
Steel fibres Check delivery note Verify that the delivery is in Each delivery
accordance with the order,
and is shipped from the
correct source
Check CE label Verify that the fibres have Each delivery
the correct CE-label which
matches the corresponding
Certificate of Conformity
Visual control, measure Compare the fibre geometry Each delivery
fibre dimensions with the fibres used for ITT
Production process inspection
Fibre content-record Record the quantity added Check the content Every batch
Fibre content in the Testing according to Conformity with the target Beginning of each day
fresh concrete EN 14721 and dosage and every
Clause 16.6.5 Verify homogeneous /50 m³ (manual dosing)
distribution of the steel /150 m³ (auto dosing)
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TABLE 16.7.5
CRITERIA OF ACCEPTANCE FOR STEEL FIBRE DOSAGE
Test control Test control Criteria
Each sample Each partial test 0.80 of the specified target dosage
Average of 3 samples Each test 0.85 of the specified target dosage
from the batch
Continuous control: Continuous control: 0.90 of the specified target dosage
average of >3 tests average of >3 tests
17.1 GENERAL
This Section sets out the material and construction requirements for bridge design.
(d) completely fill the formwork to the intended level, expel entrapped air, and closely
surround all reinforcement, tendons, ducts, anchorages, embedments and fixings; and
(e) provide the specified finish to the formed surfaces of the member.
17.3.4 Finishing of unformed concrete surfaces
Unformed concrete surfaces shall be finished by appropriate methods, to achieve the
specified—
(a) dimensions, falls, tolerances, or similar details relating to the shape and uniformity of
the surfaces;
(b) cover from the surfaces to reinforcement, tendons, ducts and embedments; and
(c) texture of the surface.
17.3.5 Curing and protection of concrete
17.3.5.1 Curing
Concrete shall be cured continuously for a period of time so the design requirements for
strength, serviceability and stripping are satisfied. To satisfy durability, curing requirements
shall be not less than those specified in Clause 4.4.
Curing shall be achieved by the application of water to accelerate the curing of, or the
retention of water in, the freshly cast concrete, and shall commence as soon as practicable
after the finishing of any unformed surfaces has been completed. Where retention of water
in the fresh concrete relies on the application of sprayed membrane-forming curing
compounds to exposed surfaces, the compounds shall comply with AS 3799.
Curing requirements for the various members of the structure shall be as detailed in the
project specification and shall be in accordance with this Standard.
17.3.5.2 Protection
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Freshly cast concrete shall be protected from the effects of rain, running water, freezing and
evaporative moisture losses prior to hardening.
17.3.6 Sampling and testing for compliance
17.3.6.1 General
Concrete, which is intended for use in structures designed in accordance with this Standard,
shall be assessed in accordance with AS 1379 for compliance with the specified parameters.
NOTE: When project assessment is required, the project specification should nominate
responsibility for carrying out the relevant sampling, testing and assessment and, if these differ
from or are not covered by AS 1379, should give details of the method of assessment.
17.3.6.2 Concrete specified by strength grade
Concrete specified by strength grade shall satisfy the following criteria:
(a) For each strength grade of concrete supplied to a project, the mean cylinder
compressive strength (fcm), as defined in AS 1379, shall be maintained within the
limits specified in that Standard.
(b) For concrete subject to project assessment—
(i) the slump of the supplied concrete shall be within the tolerance specified in
AS 1379 for the relevant specified slump; and
(ii) in addition to Item (a), the mean compressive strength of the representative
samples taken from the project shall be within the limits specified in AS 1379.
NOTES:
1 ‘Strength grade’ is defined in AS 1379 as ‘the specified value of the characteristic
compressive strength of the concrete at 28 days ( f c )’.
2 The compressive strength of the concrete sampled, tested and assessed in accordance with
AS 1379 indicates the potential strength of the supplied concrete, when placed,
compacted and cured under optimum conditions; the responsibility of demonstrating rests
on the supplier. The achievement of that potential on site is dependent upon the handling,
placing, compacting and curing techniques actually used; the responsibility for which
rests with the construction contractor (see Clauses 17.3.3 and 17.3.5).
17.3.6.3 Concrete specified by parameters other than strength grade
When concrete is specified by parameters other than strength grade, the method of
production control and, if required, project control shall be specified together with the
relevant compliance criteria.
The specified methods of control and assessment shall provide a reliable operating
characteristic curve so that—
(a) concrete with a proportion defective of 0.05 has a probability of acceptance of at least
50%; and
(b) concrete with a proportion defective of 0.30 has a probability of rejection of at least
98%.
17.3.7 Rejection of concrete
17.3.7.1 Plastic concrete
Plastic concrete may be rejected if, after completion of mixing but prior to site handling—
(a) the slump, determined in accordance with AS 1012.3.1, differs from the specified
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(iv) For the sawn or machined end of a straight bar intended for use as an end-
bearing splice, the angular deviation from square, measured in relation to the
end 300 mm, shall be within .......................................................................... 2°.
(b) Bending of reinforcement shall comply with Clause 17.4.3.
(c) If required, welding shall comply with AS/NZS 1554.3. Locational tack welding shall
be used only when consumed by final welds compliant with AS/NZS 1554.3.
Welding of stainless steel shall be in accordance with AS/NZS 1554.3 and
AS/NZS 1554.6.
NOTE: Welding of stainless steel reinforcement is not recommended.
17.4.3 Bending
17.4.3.1 General
Reinforcement shall be bent either—
(a) cold, by the application of a force, around a pin of diameter complying with
Clause 17.4.3.2, so as to avoid impact loading of the bar and mechanical damage to
the bar surface; or
(b) hot, provided—
(i) the steel is heated uniformly through and beyond the portion to be bent;
(ii) the temperature of the steel does not exceed 600°C;
(iii) the bar is not cooled by quenching;
(iv) if during heating the temperature of the bar exceeds 450°C, the design yield
strength of the steel after bending is taken as 250 MPa; and
(v) the reinforcement is not stainless steel.
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Reinforcement that has been bent and subsequently straightened or bent in the reverse
direction shall not be bent again within 20 bar diameters of the previous bend.
Bars shall not be bent using impact (e.g. such as with hammers).
Reinforcement partially embedded in concrete may be field-bent, provided the bending
complies with Items (a) or (b) above and the bond of the embedded portion is not impaired
thereby and the reinforcement is not stainless steel.
NOTE: If site rebending is to occur, then the following procedures should be stipulated for steel
reinforcement complying with AS/NZS 4671:
(a) Rebending of bars should preferably be undertaken using an approved rebending tool. Bars
should preferably be rebent against a flat surface or a pin with a diameter that is at least
equal to or greater than the minimum pin size as specified in Clause 17.4.3.2. Bars should
not be over-bent beyond the original bend, typically 90°.
(b) A pipe with an internal diameter not greater than 2db inserted over the bar may be used,
provided adequate care is taken and supervision provided; however, bending with pipes
should be carried out with a single, smooth continuous action. The pipe should be not less
than 1.2 m long.
(c) If scabbling tools have to be used near bars because of concrete leakage or contamination,
extreme care should be exercised to prevent any impact or damage to the bars.
(d) The bar should be positioned with the initial bend of the bar clear of the concrete.
steel. Pins used for stainless steel shall be made from stainless steel.
17.4.4 Surface condition
At the time concrete is placed, the surface condition of reinforcement shall be such as to not
impair its bond to the concrete or its performance in the member. The presence of millscale
or surface rust shall not be cause for rejection of reinforcement under this Clause unless
present on stainless steel reinforcement.
17.4.5 Fixing
17.4.5.1 General
All reinforcement, including secondary reinforcement provided for the purpose of
maintaining main reinforcement and tendons in position shall be supported and maintained
in position within the tolerances given in Clause 17.7.3 until the concrete has hardened.
17.4.5.2 Bar chairs and spacers
Bar chairs and spacers shall be in accordance with AS/NZS 2425.
Bar chairs and spacers within the cover concrete shall be made of durable concrete,
stainless steel or plastic materials strong enough to withstand the imposed loads and
environmental conditions without movement of the steel reinforcement, shall be positively
attached to the steel reinforcement, and shaped to facilitate placement and compaction of
concrete around the spacer to produce durable dense concrete protection to the steel
reinforcement.
The strength and durability of concrete bar chairs and spacers shall be the same or better
than the concrete member in which they are placed. Plastics coated carbon steel bar chairs
shall not be used at surfaces in exposure classes B1, B2, C1 or C2.
In addition to the requirements of AS/NZS 2425, sampling and testing, sample size and
frequency of routine testing for bar chairs and spacers shall be as approved by the relevant
authority.
Permeability testing for concrete bar chairs and spacers shall be as approved by the relevant
authority.
Wire used to tie stainless steel reinforcement shall be of stainless steel.
Bar chairs and spacers for stainless steel reinforcement shall not contain carbon steel.
17.4.6 Lightning protection by reinforcement
Where lightning protection is to be provided by the reinforcement, the reinforcement shall
comply with the relevant requirements of AS/NZS 1768.
Hard-drawn, high tensile steel wire, which has not been stress-relieved, shall not be used
for wire winding unless its elongation, tested in accordance with AS/NZS 4672.2, is 3.5%
or greater.
Plain wire shall not be used for pretensioning.
17.5.2 Construction requirements for ducts
17.5.2.1 Surface condition
When concrete is placed, the outside surface of sheaths and formers for ducts shall be such
as not to impair bond of the concrete to the duct. Immediately before grouting, the inside
surfaces of sheaths shall be such as not to impair bond of the grout to the duct.
Where an extractable core is used, a suitable technique shall be chosen to ensure its
withdrawal, without damage to the formed duct.
17.5.2.2 Sealing
Prior to the placing of concrete, ducts shall be sealed at the ends and at all joints, to exclude
concrete or other matter.
17.5.2.3 Fixing
Ducts shall be supported and fixed at regular intervals so the required tendon profile will be
maintained in accordance with Clause 17.7.3.
17.5.4.2 Protection
Before stressing, tendons shall be protected from stray current arcing and splashes from the
cutting operation of an oxy-acetylene torch or an arc-welding process.
The threaded ends of prestressing bars shall be provided with suitable protection, at all
times.
If tendons are to have a coating or wrapping, such coating or wrapping shall be inert with
respect to both the steel and the concrete.
After stressing and anchoring, all tendons and anchorages shall be protected from physical
damage and corrosion.
17.5.4.3 Surface condition
The surface condition of tendons shall be such as not to impair bond to the concrete or
grout, or performance in the member.
The presence of surface rust shall not be cause for rejection of ducts under this Clause
unless the steel is visibly pitted.
17.5.4.4 Fixing
All tendons shall be supported and maintained in position within the permissible tolerances
given in Clause 17.7.3 until the concrete has hardened.
17.5.4.5 Tensioning
Tensioning of tendons shall be carried out in a safe manner and in accordance with the
following:
(a) The stressing procedure shall ensure the force in a tendon increases at a uniform time
rate and that the force is transferred gradually to the concrete.
(b) The prestressing force applied to the tendon shall be measured at the jack by
measuring the jack pressure. The prestressing force shall be measured to an accuracy
of 3%.
(c) The tendon extension shall be measured.
(d) A check shall be made for each tendon, on the correlation between the measured
extension and the calculated extension derived from the prestressing force, using the
load-elongation curves for the tendons and assumed friction values for the cable. Any
disparity between the two figures greater than 10% of the calculated extension shall
be investigated.
(e) No stressing shall be carried out when the temperature of the surrounding air is lower
than 0°C.
17.5.4.6 Maximum jacking forces
The maximum force to be applied to a tendon during the stressing operation shall not
exceed—
(a) for pretensioned tendons ............................................................................... 0.80 fpbAp;
(b) for stress-relieved post-tensioned tendons ................................................ 0.85fpbAp; or
(c) for post-tensioned tendons and bars not stress-relieved ................................. 0.75fpbAp.
17.5.4.7 Grouting
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The deviation of any point on a surface of a member, from a straight line joining any two
points on the surface, shall not exceed 1/250 times the length of the line or 10 mm,
whichever is the greater.
17.7.3 Tolerance on position of reinforcement and tendons
The deviation from the specified position of reinforcement and tendons shall be not greater
than the following:
(a) For positions controlled by cover—
(i) in beams, slabs, columns and walls ................................................. 5, +10 mm;
(ii) in slabs-on-ground ................................................................. 10, +20 mm; and
(iii) in footings cast in the ground ........................................................ 20, +40 mm,
where a positive value indicates the amount the cover may increase and a negative
value indicates the amount the cover may decrease.
(b) For positions not controlled by cover, namely—
(i) the location of tendons on a profile ........................................................... 5 mm;
(ii) the position of the ends of reinforcement ......................................... 50 mm; and
(iii) the spacing of bars in walls and slabs and of fitments in beams and columns . 10%
of the specified spacing or 15 mm, whichever is greater.
For fitments that are nominally planar, the plane of the fitment may be skewed by not
more than three bar diameters of the fitment. The spacing of fitments shall be
measured between the same location on adjacent fitments.
Standards Australia www.standards.org.au
201 AS 5100.5:2017
17.8 FORMWORK
17.8.1 General
The materials, design and construction of formwork shall comply with AS 3610.1.
17.8.2 Stripping of forms and removal of formwork supports
17.8.2.1 General
The stripping of forms and the removal of formwork supports shall comply with the
following:
(a) Forms shall not be stripped or any formwork supports removed until the part of the
member that will be left unsupported has attained sufficient strength to support, with
safety and without detriment to its intended use, its own weight and any
superimposed loads due to concurrent or subsequent construction works.
(b) Removal of formwork supports shall be carried out in a planned sequence so the
concrete structure will not be subject to any unnecessary deformation, impact, or
eccentric loading during the process.
17.8.2.2 Removal of formwork from vertical surfaces
Formwork shall not be removed from vertical surfaces unless the concrete in the member
has achieved sufficient strength to withstand potential damage to its surfaces.
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APPENDIX A
TESTING OF MEMBERS AND STRUCTURES
(Normative)
A1 GENERAL
This Appendix sets out methods for testing a new structure or a prototype to demonstrate
compliance with the strength and serviceability requirements of this Standard. In addition, a
procedure is set out to demonstrate routine compliance for similar units manufactured
following prototype testing. Methods for testing hardened concrete in place are also
detailed.
All testing shall be undertaken by persons competent, and with appropriate expertise in,
performing such tests.
This Appendix shall not take precedence over AS 5100.7 unless approved by the authority.
NOTES:
1 This Appendix does not apply to testing for compliance of other limit states, such as for fire
or durability.
2 The capacity of an existing structure to carry repeated live loads can also be determined in
accordance with AS 5100.7. For testing of culverts, the capacity may be determined in
accordance with AS 1597.2.
A2 TESTING OF MEMBERS
A2.1 Purpose of testing
Structures designed by calculation in accordance with other parts of this Standard are not
required to be tested. Tests may be accepted as an alternative to calculation (prototype
testing), or may become necessary in special circumstances (proof testing), in order to
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satisfy the requirements of Clause 2.3 with respect to strength and Clause 2.4 with respect
to serviceability.
Where testing is necessary, elements of structures or whole structures shall be either—
(a) proof-tested in accordance with Paragraph A3, to ascertain the structural
characteristics of an existing member or structure; or
(b) prototype-tested in accordance with Paragraph A4, to ascertain the structural
characteristics of a particular class of member, which are nominally identical to the
elements tested.
A2.2 Test set-up
All measuring equipment shall be chosen and calibrated to suit the range of measurements
anticipated, in order to obtain measurements of the required precision. Care shall be
exercised to ensure that no artificial restraints are applied to the test specimen. All
necessary precautions shall be taken such that in the event of collapse of any part of a
structure being tested, the risk to life is minimized and the collapse will not endanger the
safety of the structure being tested (for tests on members) and/or adjacent structures.
A2.3 Test load
The test load shall simulate 100% of the design loads for the limit states for strength and
serviceability, as appropriate. The test load shall be applied gradually at a rate as uniform as
practicable and without impact. The distribution and duration of forces applied in the test
shall be representative of those forces to which the structure is deemed to be subject under
the requirements of this Standard.
A3 PROOF TESTING
A3.1 Test procedures
A proof test shall be conducted as follows:
(a) Before applying any load, record the original position of the members involved.
(b) Apply the test load as determined from Paragraph A2.3, for the relevant limit state.
(c) Maintain the test load for the necessary period as stated in Paragraph A3.2.
(d) Remove the test load.
A3.2 Criteria for acceptance
Criteria for acceptance shall be as follows:
(a) Acceptance for strength The test structure or member shall be deemed to comply
with the requirements for strength if it is able to sustain the strength limit state test
load for at least 24 h without incurring any significant damage such as spalling or
excessive cracking.
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(b) Acceptance for deflection The test structure or member shall be deemed to comply
with the requirements for serviceability if it is able to sustain the serviceability test
load for a minimum of 24 h without exceeding the appropriate serviceability limits.
Appropriate deflection limits for beams and slabs shall be determined using Clause 2.4.2
and the deflections calculated taking into account long-term and short-term effects,
allowing for the age and loading history of the structure.
A3.3 Damage incurred during test
The test specimen shall be regularly inspected to determine the nature and extent of any
damage incurred during the test. The effects of the damage shall be considered and the test
disbanded if collapse seems likely. At the completion of the test, appropriate repairs to
damaged parts shall be carried out.
A3.4 Test report
A report shall be prepared, which shall include, in addition to the test load-deflection
history and serviceability criteria records, a clear description of the test set-up, including
the methods of supporting and loading the members, the method of measuring deflections,
crack-widths, and so on, and any other relevant data. The report shall also include a
statement as to whether or not the structure, substructure or members tested satisfied the
relevant acceptance criteria of Paragraph A3.2, as appropriate.
A4 PROTOTYPE TESTING
A4.1 Construction of prototypes
Prototypes shall be constructed from materials that comply with this Standard, and
manufactured in accordance with the specification for the member.
TABLE A4.3
FACTOR TO ALLOW FOR VARIABILITY
IN PRODUCTION OF UNITS
(b) Acceptance for strength The test prototype shall be deemed to comply with the
requirements for strength if it is able to sustain the strength limit state test load for at
least 5 min without incurring any significant damage, such as spalling or excessive
cracking.
(c) Acceptance for serviceability The test prototype shall be deemed to comply with the
requirement for serviceability if it is able to sustain the serviceability test load for a
minimum period of 1 h without exceeding the serviceability limits appropriate to the
member. Deflection limits shall be determined using Clauses 2.4.2 and 2.4.3, taking
into account only short-term effects.
Qualitative indicators for the parameters affecting strength and serviceability shall be
determined for the expected variability during production. These indicators shall be
routinely monitored and measured in manufactured units and used to ensure the actual
coefficient of variation in production does not exceed the expected coefficient of variation.
Alternatively, manufactured units shall be routinely tested to failure, to determine the
coefficient of variation.
A4.6 Test report
A report shall be prepared in accordance with Paragraph A3.4, except that instead of the
requirement in the final sentence of Paragraph A3.4, the report shall contain a statement as
to whether or not the prototypes tested satisfied the relevant acceptance criteria in
Paragraph A4.5 as appropriate.
A5 QUALITY CONTROL
A5.1 General
This Paragraph (A5) applies to the assessment of a group of units that are part of a
production run of similar units. Paragraphs A5.2, A5.3 and A5.4 identify three methods to
routinely assess production. One of these methods shall be nominated by the manufacturer
as the means of demonstrating that the manufactured group is similar to the tested
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prototypes. The nominal routine examination shall include the determination of the
variability in a production run by relating key indicators in the sample to the previously
performed prototype testing and the application of a test load to each sample, as
appropriate.
A5.2 Statistical sampling
A sampling plan, in accordance with AS 1199.1, shall be established for the routine
inspection and testing of a produced batch. Sampling shall be undertaken in accordance
with this plan and the selected specimens shall be routinely tested to ensure compliance
with this Appendix is maintained.
For concrete specified by strength, the methods of production and assessment, taken
together, shall provide a reliable operating characteristic curve so that—
(a) concrete with a proportion defective of 0.05 has a probability of acceptance of not
less than 50%; and
(b) concrete with proportion defective of 0.30 has a probability of rejection of not less
than 98%.
A5.3 Product certification
To ascertain whether a production run or application routinely complies with the
requirements of this Appendix, independent assurance of the claim by a manufacturer or
contractor of batch consistency shall be permitted.
NOTE: The certification should meet the criteria described in ISO/IEC TR 17026 in order that
effective quality planning to control production is achieved.
quality. In particular, comparable concrete should be of similar maturity, curing history and
mix composition. Alternatively, where approved by the authority, values obtained by non-
destructive tests may be used directly to assess some properties of concrete.
The method of testing and assessment shall be specified and carried out in accordance with
internationally recognized procedures.
NOTE: Combined non-destructive techniques have been found to substantially improve the order
of accuracy of the estimated values compared with those obtained from testing by a single
method.
A6.4 Tests on samples taken from the structure
A6.4.1 Test requirements
Taking and testing of cores and beams from members and sample panels shall comply with
the following:
(a) Core and beam locations shall be selected so as to minimize any consequent reduction
of strength, durability and performance of the structure.
(b) The cores and beams shall be representative of the whole of the concrete concerned
and in no case shall less than three samples be tested.
(c) Cores and beams shall be examined visually before and after testing, to assess the
proportion and nature of any voids, cracks and inclusions present. These factors shall
be considered in the interpretation of the test results.
(d) Cores shall be taken and tested for compressive strength in accordance with
AS 1012.14 and beams shall be taken in accordance with ASTM C42. The beams
shall be tested for flexural strength in accordance with AS 1012.11, and shall be
tested dry unless the concrete concerned will be more than superficially wet in
service. The density of cores and beams shall be determined in accordance with
AS 1012.12, in the same condition as applicable to testing for compressive strength
using AS 1012.1 or AS 1012.2 by sealing or wrapping samples where appropriate.
A6.4.2 Interpretation of results
The strength of the concrete in the member shall be estimated—
(a) as 1.15 times the average strength of the cores and beams; or
(b) by using test data from cores or beams taken from another member for which the
strength of the concrete is known.
Inter l o c k in g bar s
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S p ir al
r e i nfor c e m e nt
APPENDIX B
BEAM STABILITY DURING ERECTION
(Normative)
A beam being lifted either by vertical or inclined slings may collapse or be damaged by
excessive cracking due to tilting of the beam about a longitudinal axis through the lifting
points. This initial tilting may be initiated by imperfections in the beam geometry and in the
eccentric location of the lifting points.
The stability of a prestressed beam lifted at or near the ends by vertical slings, which allow
rotation about the longitudinal axis through the lifting points (see Figure B1), shall be
determined as follows:
(a) Calculate the factor of safety against lateral buckling (ψr) as follows:
eo
r . . . B1
0.64 h
where
eo = vertical eccentricity between the centre of gravity of a beam and the
longitudinal axis through the lifting points
= yt 0.67Δv . . . B2
Δh = lateral deviation of a slender beam at midspan from the specified datum
line immediately after transfer
yt = depth from the centroidal axis to the extreme fibre at the top of the
section
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y e x Ec c e ntr i c it y
www.standards.org.au
of lif t in g p o int
A e o = d y. s u p - 0.67Δ v
Lif t ing Lif t ing Lif t ing
p o int p o int p o int
d y. s u p
βv
Datum line
x Centre of grav it y
of beam in elevation Δv
209
A
x M aj or
axis ELE VATIO N Lif t ing
Lif t ing p o int
p o int
ex e x + 0.67 Δ h Δh
Datum line
CL of b eam
M i n or a x i s
y
C e ntre of gr av it y of
SECTIO N A-A beam in plan
PL AN
Standards Australia
AS 5100.5:2017
AS 5100.5:2017 210
APPENDIX C
DESIGN OF SEGMENTAL CONCRETE BRIDGES
(Normative)
C1 ANALYSIS
C1.1 Longitudinal analysis
Longitudinal analysis of segmental concrete bridges shall consider a specific construction
method and construction schedule, as well as the time-related effects of concrete creep,
shrinkage and prestress losses.
The effects of secondary moments due to prestress shall be included in stress calculations at
serviceability limit states. In calculating flexural and shear resistance requirements at the
strength ultimate limit states, the secondary moments or shears induced by prestress (with a
load factor of 1.0) shall be added to the moments and shears due to factored dead and live
loads.
C1.2 Transverse analysis
Consideration shall be given to the increase in web shear, transverse web flexure and other
effects on the cross-section resulting from eccentric loading or asymmetry of the structural
geometry.
C1.3 Deflection calculations
Prior to casting segments, deflections shall be calculated based on the anticipated casting
and construction sequence and schedules. The calculated deflections shall be used as a
guide for presetting the girders and for checking actual deflections during construction.
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C2 LOADS
C2.1 Erection loads
Erection loads comprise all loadings arising from the anticipated system of temporary
supporting works or special erection equipment, or both, to be used in accordance with the
assumed construction sequence and schedule. The assumed erection loads and acceptable
closure forces due to misalignment corrections shall be stated on the drawings. Allowance
shall be made for all effects of changes to the statical structural scheme during construction
and the application, changes or removal of the assumed temporary supports and special
equipment, taking into account residual ‘built-in’ forces, moments, deformations, secondary
post-tensioning effects, creep, shrinkage and any other strain-induced effects.
C2.2 Post-tensioning force
The structure shall be designed for both the initial and final post-tensioning forces. For
determining the final post-tensioning forces, prestress losses shall be calculated for the
proposed construction schedule stated on the plans. The final post-tensioning forces used in
serviceability limit state stress calculations shall be based on the most severe condition at
each location along the structure.
C3 SHEAR AT JOINTS
Interfaces between elements such as webs and flanges, between dissimilar materials,
between concretes cast at different times or at an existing or potential major crack shall be
designed for shear transfer in accordance with Clause 8.4.
Shear keys in webs of precast segmental bridges shall extend for as much of the web height
as is compatible with other detailing requirements. Alignment shear keys shall be provided
in top and bottom flanges.
The ultimate shear strength (Vu ) for structures utilizing dry joints shall equal the nominal
shear resistance (Vuj) at the joint and shall be calculated as follows:
A
Vuj 1.875 Ak f ct 1 0.205 cp p 0.45 Asm cp . . . C3
Ag
where
Ak = area of the base of all the keys in the failure plane, in millimetres square
f ct = principal tensile strength of the concrete
σcp = average intensity of effective prestress in concrete
Asm = area of contact between smooth surfaces on the failure plane, in millimetres
square
C5 SPECIAL PROVISIONS
C5.1 Precast segmental construction
C5.1.1 Age of segments at erection
To limit construction deflections to values consistent with design calculations, precast
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segments shall be a minimum of 14 days old at the time of erection unless earlier erection is
specifically approved.
C5.1.2 Temporary stress on epoxy joints
A minimum compressive stress of 0.28 MPa shall be provided for the closure stress on an
epoxied joint until the epoxy has set.
C5.1.3 Dry joints
Dry joints shall not be used—
(a) for bridges with internal tendons; or
(b) in conjunction with external post-tensioning tendons in areas with exposure
classification B2 or C, or where freeze/thaw cycles occur.
C5.1.4 External tendons
At least three levels of corrosion protection of post-tensioning tendons shall be provided.
A waterproof membrane shall be provided on externally post-tensioned bridge
superstructures.
The bridge shall be detailed to allow for the inspection and replacement of external
prestressing tendons.
C6 SPECIFICATIONS
The method of construction shall be taken into consideration when designing the permanent
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works. Assumptions used in the design of the permanent works pertaining to the method of
construction shall be included in the drawings or specification. Tolerances shall be provided
regarding the construction equipment weights and variations in material properties to be
used.
Allowances shall be shown for variations in construction loads and construction stages. The
resultant camber information shall be given such that development of casting curves can be
achieved.
APPENDIX D
STANDARD PRECAST PRESTRESSED CONCRETE GIRDER
(Informative)
D1 GENERAL
The standard sections for precast, prestressed concrete bridge girders shown in
Figure D1(A) for I-girders and in Figure D1(B) for Super T-girders, have been adopted. For
the Super T-girder sections, the size of the internal void has not been detailed.
In addition, Figure D1(C) shows the earlier dimensions of Super T-girders used up until
mid-2001 when the width of the bottom flange was increased to enable the addition of a
deeper section to a common mould shape.
NOTE: Cover in excess of 25 mm required for durability may require increased width of the webs
of standard sections.
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350
20 0
40
10 0
10 0 10 0
C e nt r o i d a l 15 0
120
axis
420 900 450
75 0
Yb
15 0
10 0
10 0
90
300
450
T YPE 1 T YPE 2
G ir d er Ag Z y. s u p Z y. s u p I d y. s u b H y p ot h et i c a l t h i c k n e s s, t h
type (m m 2 ) (m m 3 ) (m m 3 ) (m m 4) (m m) (g ir d er s o nly)(m m)
1 126 x 10 3 17.9 x 10 6 2 2.0 x 10 6 74 0 0 x 10 6 3 37 120
2 218 x 10 3 41.1 x 10 6 4 8.1 x 10 6 19 9 5 0 x 10 6 415 15 5
3 317 x 10 3 8 2.9 x 10 6 91.1 x 10 6 4 9 9 0 0 x 10 6 548 18 0
4 4 4 3 x 10 3 13 5.9 x 10 6 16 8.6 x 10 6 10 5 3 3 0 x 10 6 6 25 20 5
500
450
15 0
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13 0
175
15 0
15 0 15 0
545 650
115 0 14 0 0
175
25 0
15 0
175
500
650
T YPE 3 T YPE 4
DIMENSIONS IN MILLIMETRES
A 10 27 A
10 27 75 m in.*
A A
75 m in.*
10 0 x 75
13 x 13 fillet (t y p)
* 10 0 x 75 c hamfer * 10 0 0
13 x 13 fillet (t y p) 75 0
c hamfer
= = tb 426 426 tb
899 N o m i n a l 10 r ad i u s 8 52 N o m i n a l 10 r ad i u s
or 13 x 13 c hamfer or 13 x 13 c hamfer
(a) Ty p e T1 - 2 (b) Ty p e T2 - 2
A 10 27 A
75 m in.*
A 10 27 A
75 m in.*
10 0 x 75
13 x 13 fillet (t y p)
c hamfer
10 0 x 75 *
13 x 13 fillet (t y p) 15 0 0
c hamfer
* 120 0
4 07 4 07 tb tb
814 N o m i n a l 10 r ad i u s 757 N o m i n a l 10 r ad i u s
or 13 x 13 c hamfer or 13 x 13 c hamfer
(c) Ty p e T3 - 2 (d) Ty p e T4 - 2
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A 10 27 A
75 m in.*
10. 5 5 6
1
5.3 47
10 0 x 75 To p s l o p e of
13 x 13 fillet (t y p) b ot to m fl an g e
c hamfer 1
* We b s l o p e
18 0 0 25 x 25
re c e s s 25
25
70 0 N o m i n a l 10 r ad i u s LEGEN D:
or 13 x 13 c hamfer = D e n ote s d im e n s i o n ha s to b e in c rea se d
if fl an g e t hi c k n e s s > 75
(e) Ty p e T5 - 2 * = D e n ote s d i m e n s i o n s var i e s
DIMENSIONS IN MILLIMETRES
A 9 20 A
75 m in.*
A 9 20 A
75 m in.*
*
10 0 x 75
fillet (t y p)
* 10 0 0
10 0 x 75
75 0
fillet (t y p)
79 2 N o m i n a l 10 r ad i u s 74 4 N o m i n a l 10 r ad i u s
or 12 x 12 c hamfer or 12 x 12 c hamfer
(a) Ty p e T1 - 1 (b) Ty p e T2 - 1
A 9 20 A
75 m in.*
A 9 20 A
75 m in.*
*
10 0 x 75
fillet (t y p)
*
10 0 x 75
fillet (t y p) 15 0 0
120 0
353 353 tb 3 25 3 25 tb
70 6 N o m i n a l 10 r ad i u s 650 N o m i n a l 10 r ad i u s
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or 12 x 12 c hamfer or 12 x 12 c hamfer
(c) Ty p e T3 - 1 (d) Ty p e T4 - 1
25 x 25
re c e s s 25
10. 5 5 6
1 25
5.0 0 0
1
To p s l o p e of We b s l o p e Detail A
b ot to m fl an g e
LEGEN D:
= D e n ote s d i m e n s i o n h a s to b e i n c r e a s e d
if fl an g e t hi c k n e s s > 75
* = D e n ote s d i m e n s i o n s var i e s
DIMENSIONS IN MILLIMETRES
TABLE D2
END BLOCK DIMENSIONS FOR POST-TENSIONED I-GIRDERS
Girder type End block length End block width Taper length
(see Note)
mm mm mm mm
1 750 200 70
2 900 350 170
3 1 150 450 260
4 1 400 500 300
NOTE: The taper length is the length of the tapered section between the end block and
the web of the beam.
D3 FLEXURAL PROPERTIES
Flexural moduli about the major axis of bending for standard precast prestressed concrete
I-girder sections are given in Table D3(A).
Flexural moduli about the major axis of bending are also given for a typical range of Super
T-girder sections that conform to the standard sections shown in Figure D1(B), with the
following dimensions:
(a) Width of webs: 100 mm (for girder types 1 to 4).
120 mm (for girder type 5).
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TABLE D3(A)
FLEXURAL MODULUS—PRECAST CONCRETE I-GIRDERS
Girder Ag Zt Zb I yb th
type (girders only)
mm 2 10 3 mm 3 10 6 mm 3 10 6 mm 4 10 6 mm mm
1 125 17.9 22.0 7 400 337 120
2 218 41.1 48.1 19 950 415 155
3 317 82.9 91.1 49 900 548 180
4 443 135.9 158.5 105 330 625 205
where
A g = gross sectional area of the member
Z t = section modulus about the centroidal axis at the top of an uncracked cross-section
Z b = section modulus about the centroidal axis at the bottom of an uncracked cross-section
I = second moment of area of the uncracked concrete cross-section
y b = depth from the centroidal axis to the extreme fibre at the bottom of the section
th = hypothetical thickness of the member
TABLE D3(B)
FLEXURAL MODULUS—PRECAST CONCRETE SUPER T-GIRDERS—
OPEN TOP FLANGE CASE
Girder tb Ag Zt Zb I yb th
type (girders only)
mm mm 2 10 3 mm 3 10 6 mm 3 10 6 mm 4 10 6 mm mm
T1-2 240 436.0 67.4 84.4 28 100 323 139
T2-2 240 472.1 104.6 132.1 58 390 442 131
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D4 TORSIONAL PROPERTIES
Torsional moduli (Jtb) of the standard precast prestressed concrete I-girder sections,
together with torsional moduli (Jtn) of the I-girder sections with a composite slab connected
above, taking into account the difference in elastic moduli of the girder and slab concretes,
as shown in Figure D4(A), are given in Table D4(A).
Torsional moduli are given for typical Super T-girder sections that conform to the standard
sections shown in Figure D1(B), with the following dimensions:
(a) Width of webs: 100 mm (for girder types 1 to 4).
120 mm (for girder type 5).
(b) Thickness of top flange: 75 mm.
(c) Width of top flange: 2100 mm.
(d) Thickness of bottom Dimension tb [see Table D3(B)].
flange at centre-line:
Torsional moduli (Jtb) of the standard precast prestressed concrete Super T-girder sections,
together with torsional moduli (Jtn) of the Super T-girder sections with a composite slab
connected above, taking into account the difference in elastic moduli of the girder and slab
concretes, shown in Figures D4(B)(1) and D4(B)(2), are given in Table D4(B)(1) for the
open top flange case and in Table D4(B)(2) for the closed top flange case.
For the application of the torsional moduli, the following considerations apply:
(i) Torsional moduli, given in Tables D4(A), D4(B)(1) and D4(B)(2) are based on elastic
theory and are equivalent to the Saint Venant’s torsional constants.
(ii) The value of torsional modulus (Jtn) for a composite section is the torsional modulus
for the girder plus the slab together with the junction effect between the girder and
the cast-in-place slab.
NOTE: The contribution to Jtn from the cast-in-place deck slab is reduced to one half of the
full amount because the continuity of the slab removes the effect of the vertical shear stresses
that would otherwise be present at the free ends of the slab.
(iii) Values of Jtn are given for modular ratios of 0.70 and 1.00 where αc is the modular
ratio factor of the cast-in-place concrete to the precast beam concrete in the
composite member. Intermediate values may be interpolated.
(iv) The width (bs) is the width of the flange in a composite member.
(v) The full torsional moduli are suitable for determining distribution of forces at applied
loads only, that is, while the section is uncracked. At ultimate load, considerable
reduction in the torsional stiffness may occur and the effect of using a torsional
modulus equal to 20% of the full value should be taken into consideration.
bs
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ds
Ca st- in - p l ac e s l a b
S t an d ar d pre c a st
p r e s t r e s s e d I - g ir d er
TABLE D4(A)
TORSIONAL MODULI (J tb) AND (J tn) FOR SECTIONS USING STANDARD
PRECAST PRESTRESSED CONCRETE I-GIRDERS
Torsional modulus
mm 4 10 6
Girder For girders in composite section, J tn
type For girder
only, d s = 150 mm d s = 175 mm d s = 200 mm
J tb
α c = 0.70 α c = 1.00 α c = 0.70 α c = 1.00 α c = 0.70 α c = 1.00
1 800 1 100 1 200 1 200 1 300 1 300 1 400
2 2 400 3 500 3 800 3 800 4 100 4 100 4 500
3 5 000 7 100 7 700 7 700 8 300 8 200 9 000
4 10 000 13 000 14 000 14 000 15 000 15 000 16 000
S t a n d ar d p r e c a s t p r e s t r e s s e d
o p e n fl an g e Su p er T- g ir d er
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bs
ds
Ca st- in - p l ac e s l a b
S t a n d ar d p r e c a s t p r e s t r e s s e d
o p e n fl an g e Su p er T- g ir d er
S t a n d ar d p r e c a s t p r e s t r e s s e d
c l o se d fl an g e Su p er T- g ir d er
bs
ds
Ca st- in - p l ac e s l a b
S t a n d ar d p r e c a s t p r e s t r e s s e d
c l o se d fl an g e Su p er T- g ir d er
TABLE D4(B)(1)
TORSIONAL MODULI (J tb) AND (J tn) FOR SECTIONS USING OPEN TOP
FLANGE STANDARD PRECAST PRESTRESSED CONCRETE SUPER T-GIRDERS
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Torsional modulus
mm 4 10 6
Girder For For girders in composite section, J tn
type tb girder
d s = 150 mm d s = 175 mm d s = 200 mm
mm only,
J tb α c = 0.70 α c = 1.00 α c = 0.70 α c = 1.00 α c = 0.70 α c = 1.00
1 240 6 300 66 000 75 000 69 000 80 000 73 000 86 000
2 240 6 100 103 000 116 000 108 000 123 000 113 000 130 000
3 260 6 900 136 000 151 000 142 000 160 000 148 000 169 000
4 260 6 400 181 000 200 000 188 000 210 000 195 000 221 000
5 325 9 900 244 000 265 000 252 000 278 000 261 000 290 000
TABLE D4(B)(2)
TORSIONAL MODULI (J tb) AND (J tn) FOR SECTIONS USING CLOSED TOP
FLANGE STANDARD PRECAST PRESTRESSED CONCRETE SUPER T-GIRDERS
Torsional modulus
mm 4 10 6
Girder For For girders in composite section, J tn
type tb girder
d s = 150 mm d s = 175 mm d s = 200 mm
mm only,
J tb α c = 0.70 α c = 1.00 α c = 0.70 α c = 1.00 α c = 0.70 α c = 1.00
1 240 49 000 67 000 76 000 70 000 81 000 74 000 87 000
2 240 83 000 109 000 121 000 114 000 128 000 119 000 136 000
3 260 114 000 145 000 160 000 151 000 169 000 157 000 177 000
4 260 156 000 196 000 214 000 203 000 225 000 210 000 235 000
5 325 215 000 261 000 282 000 269 000 294 000 278 000 306 000
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BIBLIOGRAPHY
AS
1012 Methods of testing concrete
1012.21 Method 21: Determination of water absorption and apparent volume of
permeable voids in hardened concrete
1141 Methods for sampling and testing aggregate
1141.60.1 Method 60.1: Potential alkali-silica reactivity—Accelerated mortar bar
method
1141.60.2 Method 60.2: Potential alkali-silica reactivity—Concrete prism method
1597 Precast reinforced concrete box culverts
1597.2 Part 2: Large culverts (exceeding 1200 mm span or 1200 mm height and
up to and including 4200 mm span and 4200 mm height
3735 Concrete structures retaining liquids
3735 Supp 1 Concrete structures retaining liquids (Supplement to AS 3735—2001)
3972 General purpose and blended cements
AS/NZS
3000 Electrical installation (known as the Australia/New Zealand Wiring Rules)
3500 Plumbing and drainage (series)
EN
1992 Eurocode 2—Design of concrete structures
1992-1 Part 1: General Rules And Rules For Buildings
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AS 5100.5:2017
CORRECTION
SUMMARY: This Amendment applies to the Preface, Clauses 8.2.1.2, 8.2.1.3, 8.2.1.5, 8.2.2.1, 8.2.3.3, 8.2.4,
8.2.4.1, 8.2.4.2, 8.2.4.3, 8.2.4.4, 8.2.4.5, 8.2.4.6, 8.2.4.7, 8.2.4.10, 8.2.5, 8.2.5.2, 8.2.5.5, 8.2.7, 8.2.8, 8.2.9.1,
8.2.9.3 and Equations 8.2.1.7 and 8.5.3.1.
Published on
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