IS 800:2007

the 10xI in the element spliced plus 5 percent but in no augment the strength of the web, they shall be placed
case should the strength developed be less than 50 on each side of the web and shall be equal in thickness.
percent of’the effective strength of the material spliced. The proportion of shear force assumed to be resisted
In welded construction, flange plates shall be joined by these plates shall be limited by the amount of
by complete penetration butt welds, wherever possible. horizontal shear which they can transmit to the flanges
These butt welds shall develop the full strength of the through their fastenings, and such reinforcing plates
plates. and their fastenings shall be carried up to the points
at which the flange without the additional plates is
8.6.3.3 Connection offianges to web
adequate.
The flanges of plate girders shall be connected to the
web by sufficient rivets, bolts or welds to transmit the 8.7 Stiffener Design
maximum horizontal shear force resulting from the 8.7.1 General
bending moment gradient in the girder, combined with
any vertical loads which are directly applied to the 8.7.1.1 When the web of a member acting alone (that
flange. If the web is designed using tension field is without stiffeners) proves inadequate, stiffeners for
method as given in 8.4.2.2 (b), the weld should be able meeting the following requirements should be
to transfer the tension freld stress, j’ywacting on the provided:
web, a) intermediate tramverse web st~fener — TO
8.6.3.4 Bolted/Riveted construction improve the buckling strength of a slender
web due to shear (see 8.7.2).
For girders in exposed situations and which do not have
b) Load carrying stiflener — To prevent local
flange plates for their entire length, the top edge of the buckling of the web due to
web plate shall be flush with or above the angles, and
concentrated loading (see 8.7.3 and 8.7.5).
the bottom edge of the web plate shall be flush with or
c) Bearing stl~ener — To prevent local crushing
set back from the angles.
of the web due to concentrated loading
8.6.3.5 Welded construction (see 8.7.4 and 8.7.6).
The gap between the web plates and flange plates shall d) Torsion stiflener — To provide torsional
be kept to a minimum and for fillet welds shall not restraint to beams and girders at supports
exceed 1 mm at any point before welding. (see 8.7.9).
e) Diagonal stiffener — To provide local
8.6.4 Webs
reinforcement to a web under shear and
8.6.4.1 Effective sectional area of web of plate girder bearing (see 8.7.7).
f) Tension str’’encr— To transmit tensile forces
The effective cross-sectional area shall be taken as the
applied to a web through a flange (see 8.7.8).
full depth of the web plate multiplied by the thickness.
~()’r~ — Where webs are varied in thickness in Lhedepth of The some stiffeners may perform more than one
the section by the ase of tongue plates or the like, or where the function and their design should comply with the
pt-opcrrtiunof the web included in the flange area is 25 percent requirements of all the functions for which designed.
or more of the overall depth, the above approximation is not
pcnnissib]c and the maximum shear stress shall be computed 8.7.1.2 O[ltstand of web sti~eners
on theory,
Unless the outer edge k continuously stiffened, the
8.6.4.2 Splice,v in vvebs outstand f’rom the face of the web should not exceed
Splices and cutouts for service ducts in the webs should 2ot,,E.
prefembly not be located at points of maximum shear When the outstand of web is between 14tqE and 20tq&,
force and heavy concentrated loads. then the stiffener design should be on the basis of a
Splices in the webs of the plate girders and rolled core section with an outstand of 14t~&,where tqis the
sections shall be designed to resist the shears and thickness of the stiffener.
moments at the spliced section (see Annex F). 8.7.1.3 St(~~bearing length
In riveted or bolted construction, splice plates shall be The stiff bearing length of any element b,, is that length
provided on each side of the web. In welded which cannot deform appreciably in bending. To
construction, web splices shall preferably be made with determine b], the dispersion of load through a steel bearing
complete penetration butt welds. element should be taken as 45” through solid material,
8.6.4.3 Where additional plates are required to such as bearing plates, flange plates, etc (see Fig. 15).

65
IS 800:2007

8.7.1.4 Eccentricity where

Where a load or reaction is applied eccentric to the L= length of the stiffener.

centreline of the web or where the centroid of the
stiffener does not lie on the centreline of the web, the If the load or reaction is applied to the flange by a
resulting eccentricity of loading should be accounted compression member, then unless effective lateral
for in the design of the stiffener. restraint is provided at that point, the stiffener should
be designed as part of the compression member
8.7.1.5 Buckling resistance of stiffeners
applying the load, and the connection between the
The buckling resistance F~d should be based on the column and beam flange shall be checked for the effects
design compressive stress fcd (see 7.1.2.1) of a strut of the strut action.
(curve c), the radius of gyration being taken about the
8.7.2 Design of Intermediate Transverse Web Stl~eners
axis parallel to the web. The effective section is the
full area or core area of the stiffener (see 8.7.1.2) 8.7.2.1 General
together with an effective length of web on each side
Intermediate transverse stiffeners may be provided on
of the centreline of the stiffeners, limited to 20 times
one or both sides of the web.
the web thickness. The design strength used should be
the minimum value obtained for buckling about the 8.7.2.2 Spacing
web or the stiffener.
Spacing of intermediate stiffeners, where provided,
The effective length for intermediate transverse shall comply with 8.6.1 depending on the thickness of
stiffeners used in calculating the buckling resistance, the web.
F~~, should be taken as 0.7 times the length, L of the
8.7.2.3 Outstand ofstifjleners
stiffener.
The outstand of the stiffeners should comply
The effective length for load carrying web stiffeners
with 8.7.1.2.
used in calculating the buckling resistance, FXd,
assumes that the flange through which the load or 8.7.2.4 Minimum stiffeners
reaction is applied is effectively restrained against
Transverse web stiffeners not subject to external loads
lateral movement relative to the other flange, and
or moments should have a second moment of area, Is
should be taken as:
about the centreline of the web, if stiffeners are on both
a) KL = 0.7 Lwhen flange is restrained against sides of the web and about the face of the web , if
rotation in the plane of the stiffener (by other single stiffener on only one side of the web is used
structural elements). such that:
b) KL = L, when flange is not so restrained:

t.
w

45° -&-bq—
,
‘ ‘< ;
\\ I L,
X t
‘\ \\
f
I

FIG. 15 STIFF BEARING LENGTH, b]

66
 IS 800:2007

8.7.2.6 Connection of intermediate sti$eners to web

~ > 1.5d3t;
s Intermediate transverse stiffeners not subject to
C2
external loading should be connected to the web so as
where to withstand a shear between each component of the
d= depth of the web; stiffener and the web (in kN/mm) of not less than:

tw = minimum required web thickness for t~/(5b, )

spacing using tension field action, as given
in 8.4.2.1; and where
c = actual stiffener spacing.
tw = web thickness, in mm; and
8.7.2.5 Buckling check on intermediate transverse web b, = outstand width of the stiffener, in mm.
stiffeners
For stiffeners subject to external loading, the shear
Stiffeners not subjected to external loads or moments between the web and the stiffener due to such loading
should be checked for a stiffener force: has to be added to the above value.

Stiffeners not subject to external loads or moments may

F, = V- VC,/y.O < F,,
terminate clear of the tension flange and in such a
where situation the distance cut short from the line of the weld
should not be more than 4tW.
F~~ = design resistance of the intermediate
stiffeners, 8.7.3 Load Carrying Stiffeners
v= factored shear force adjacent to the stiffener, 8.7.3.1 Web check
and
Load carrying web stiffeners should be provided where
Vcr = shear buckling resistance of the web panel compressive forces applied through a flange by loads
designed without using tension field action or reactions exceed the buckling strength, FCdW,of the
as given in 8.4.2.2(a). unstiffened web, calculated using the following:
Stiffeners subject to external loads and moments should
The effective length of the web for evaluating the
meet the conditions for load carrying web stiffeners
slenderness ratio is calculated as in 8.7.1.5. The area
in 8.7.3. In addition they should satisfy the following
of cross-section is taken as (b, + n I) tW:
interaction expression:
where

b] = width of stiff bearing on the flange

(see 8.7.1.3), and
n, = dispersion of the load through the web at
If F~c FX, then (F~– FX) should be taken as zero;
45°, to the level of half the depth of the cross-
where section.
F~ = stiffener force given above; The buckling strength of this web about axis parallel
to the web is calculated as given in 7.1.2.1, using
F~~ = design resistance of an intermediate web
stiffener corresponding to buckling about an curve ‘c’.
axis parallel to the web (see 8.7.1.5); 8.7.4 Bearing Stiffeners
FX = external load or reaction at the stiffener;
Bearing stiffeners should be provided for webs where
FX~ = design resistance of a load carrying forces applied through a flange by loads or reactions
stiffener corresponding to buckling about exceeding the local capacity of the web at its connection
axis parallel to the web (see 8.7.1.5); to the flange, FW, given by:
M~ = moment on the stiffener due to
eccentrically applied load and transverse FW= (b, + n~) twf,~ll’~o
load, if any; and
where
Mv~= yield moment capacity of the stiffener
based on its elastic modulus about its bl = stiff bearing length (see 8.7.1.3),
centroidal axis parallel to the web. rq = length obtained by dispersion through the

67
IS 800:2007

flange to the web junction at a slope of 1 :2.5 8.7.9 Torsional Stiffeners

to the plane of the flange,
Where bearing stiffeners are required to provide
tw = thickness of the web, and torsional restraint at the supports of the beam, they
.~W = yield stress of the web. should meet the following criteria:

8.7.5 Design of Load Carrying Stiffeners a) Conditions of 8.7.4, and

b) Second moment of area of the stiffener section
8.7.5.1 Buckling check
about the centreline of the web, 1, should be
The external load or reaction, FXon a stiffener should such that:
not exceed the buckling resistance, FX~of the stiffener
1, 2 o.34a, D3TC’
as given in 8.7.1.5.

Where the stiffener also acts as an intermediate stiffener where

it should be checked for the effect of combined loads U, = 0.006 for L~~It-ys 50,
in accordance with 8.7.2.5. = 0.3/( ~~ /rY) for 50< ~~ /rY= 100,
8.7.5.2 Bearing check = 30/( L~~/rY )2 for L~~Jry >100,

Load carrying web stiffeners should also be of sufficient D= overall depth of beam at support,
size that the bearing strength of the stiffener, FP,~,given TC~= maximum thickness of
below is not less than the load transferred, FX compression flange in the span
under consideration,
F,,, = A,fy,/ (0.8y~0 ) 2 F,
KL = laterally unsupported effective
where length of the compression flange
Fx = external load or reaction, of the beam, and

A~ = area of the stiffener in contact with the ‘Y =

radius of gyration of the beam
flange, and about the minor axis.
8.7.10 Connection to Web of Load Carrying and
~Y~ = yield stress of the stiffener.
Bearing Stiffeners
8.7.6 Design of Bearing Sti#eners
Stiffeners, which resist loads or reactions applied
Bearing stiffeners should be designed for the applied through a flange, should be connected to the web by
load or reaction less the local capacity of the web as sufficient welds or fasteners to transmit a design force
given in 8.7.4. Where the web and the stiffener material equal to the lesser of:
are of different strengths the lesser value should be
a) tension capacity of the stiffene~ and
assumed to calculate the capacity of the web and the
stiffener. Bearing stiffeners should project nearly as b) sum of the forces applied at the two ends of
much as the overhang of the flange through which load the stiffener when they act in the same
is transferred. direction or the larger of the forces when they
act in opposite directions.
8.7.7 Design of Diagonal Stiffeners
Stiffeners, which do not extend right across the web,
Diagonal stiffeners should be designed to carry the
should be of such length that the shear stress in the
portion of the applied shear and bearing that exceeds
web due to the design force transmitted by the stiffener
the capacity of the web.
does not exceed the shear strength of the web. In
Where the web and the stiffener are of different addition, the capacity of the web beyond the end of
strengths, the value for design should be taken as given the stiffener should be sufficient to resist the applied
in 8.7.6. force.

8.7.8 Design of Tension Sti#eners 8.7.11 Connection to Flanges

Tension stiffeners should be designed to carry the 8.7.11.1 In tension

portion of the applied load or reaction less the capacity
Stiffeners required to resist tension should be connected
of the web as given in 8.7.4 for bearing stiffeners.
to the flange transmitting the load by continuous welds
Where the web and the stiffener are of different or non-slip fasteners.
strengths, the value for design should be taken as given
8.7.11.2 In compression
in 8.7.6.
Stiffeners required to resist compression should

68
 - ...k _

,,
‘----&

IS 800:2007

either be fitted against the loaded flange or 8.8.2 Where the concentrated or moving load does not
connected by continuous welds or non-slip fasteners. act directly on top of the web, the local effect shall be
considered in the design of flanges and the diaphragms.
The stiffener should be fitted against or connected to
both flanges when: 8.9 Purlins and Sheeting Rails (Girts)
a) a load is applied directly over a support, or All purlins shall be designed in accordance with the
b) it forms the end stiffener of a stiffened web, requirements for uncased beams as specified in 8.2.1
or and 8.2.2, and the limitations of bending stress based
c) it acts as a torsion stiffener. on lateral instability of the compression flange and the
limiting deflection specified under 5.6.1 for the design
8.7.12 Hollow Sections
of purlins. The maximum bending moment shall not
Where concentrated loads are applied to hollow exceed the values specified in 8.2.1. The calculated
sections consideration should be given to local stresses deflections should not exceed those permitted for the
and deformations and the section reinforced as type of roof cladding used as specified in 5.6.1. In
necessary. calculating the bending moment, advantage may be
taken of the continuity of the purlin over supports. The
8.7.13 Horizontal Stiffeners
bending about the two axes should be determined
Where horizontal stiffeners are used in addition to separately and checked according to the biaxial
vertical stiffeners, they shall be as follows: bending requirements specified in Section 9.

a) One horizontal stiffener shall be placed on the 8.10 Bending in a Non-principal Plane
web at a distance from the compression flange
equal to 1/5 of the distance from the 8.10.1 When the flexural deflection of a member is
compression flange angle, plate or tongue constrained to a non-principal plane by lateral restraints
plate to the neutral axis when the thickness preventing lateral deflection, then the force exerted by
of the web is less than the limits specified the restraints shall be determined, and the principal
in 8.6.1. The stiffener shall be designed so axes bending moments acting on the member shall be
that I, is not less than 4ctW>where 1, and tWare calculated from these forces and applied forces, by a
as defined in 8.7.2.4 and c is the actual rational analysis. The combined effect of bending
about the principal axes shall satisfy the requirements
distance between the vertical stiffeners
of Section 9.
b) A second horizontal stiffener (single or
double) shall be placed at the neutral axis of 8.10.2 When the deflections of a member loaded in a
the girder when the thickness of the web is non-principal plane are unconstrained; the principal
less than the limit specified in 8.6.1. This axes bending moments shall be calculated by a rational
stiffener shall be designed so that 1, is not less analysis. The combined effect of bending about the
than dz tw~ where I, and tw are as defined principal axes shall satisfy the requirements of
in 8.7.2.4 and dz is twice the clear distance Section 9.
from the compression flange angles, plates or
tongue plates to the neutral axis; SECTION 9
c) Horizontal web stiffeners shall extend MEMBER SUBJECTED TO COMBINED
between vertical stiffeners, but need not be FORCES
continuous over them; and
d) Horizontal stiffeners may be in pairs arranged 9.1 General
on each side of the web, or single located on This section governs the design of members subjected
one side of the web. to combined forces, such as shear force and bending,
8.8 Box Girders axial force and bending, or shear force, axial force and
bending.
The design and detailing of box girders shall be such
as to give full advantage of its higher load carrying 9.2 Combined Shear and Bending
capacity. Box girder shall be designed in accordance
9.2.1 No reduction in moment capacity of the section is
with specialist literature. The diaphragms and
necessary as long as the cross-section is not subjected
horizontal stiffeners should conform to 8.7.12
to high shear force (factored value of applied shear force
and 8.7.13.
is less than or equal to 60 percent of the shear strength
8.8.1 All diaphragms shall be connected such as to of the section as given in 8.4). The moment capacity
transfer the resultant shears to the web and flanges. may be tiiken as, M~ (see 8.2) without any reduction.

69
IS 800:2007

9.2.2 When the factored value of the applied shear force where
is high (exceeds the limit specified in 9.2.1), the
MY,M, = factored applied moments about the
factored moment of the section should be less than the
minor and major axis of the cross-section,
moment capacity of the section under higher shear
respectively;
force, lkf~,, calculated as given below:
M~~Y,
Mn~Z= design reduced flexural strength under
a) Plastic or Compact Section combined axial force and the respective
uniaxial moment acting alone (see
M,, = Jf, – P(%–W,) ~ 1.’2-%f,/Ymo
9.3.1.2);
where N= factored applied axial force (Tension, T
or Compression, P);
p= (2v/vd-1)2 N~ = design strength in tension, Tdas obtained
M~ = plastic design moment of the from 6 or in compression due to yielding
whole section disregarding high given by N, = A~.fYlY~O;
shear force effect (see 8.2.1.2)
M~Y,M~Z = design strength under corresponding
considering web buckling effects
moment acting alone (see 8.2);
(see 8.2.1.1),
A~ = gross area of the cross-section;
v= factored applied shear force as
governed by web yielding or web a,, (X2 = constants as given in Table 17; and
buckling, Klo = partial factor of safety in yielding.
Vd = design shear strength as governed 9.3.1.2 For plastic and compact sections without bolts
by web yielding or web buckling holes, the following approximations may be used for
(see 8.4.1 or 8.4.2), evaluating Mn~Yand Mn~Z:
Mfd = plastic design strength of the area a) Plates
of the cross-section excluding the
Mn~= M~(l –n2)
shear area, considering partial
safety factor ymO,and b) Welded I or H sections
Ze = elastic section modulus of the 2

b)
whole section.
Semi-compact Section
Mn,Y= M,,
[( )]
1- ~ 5 MdYwhere n > a

M.~Z= M~Z(1 -n)/(1 –0.5a) SM~Z

~dv = Z fvi y.,

where
9.3 Combined Axial Force and Bending Moment
n = N/N~ anda = (A–2bt~)/A <0.5
Under combined axial force and bending moment, section
strength as governed by material failure and member c) For standard I or H sections
strength as governed by buckling failure shall be checked for n s 0.2 M.,, = M,,
in accordance with 9.3.1 and 9.3.2 respectively. for n >0.2 MtiY = 1.56 MdY(l -n)(n +0.6)
9.3.1 Section Strength Mnd,= l.ll MdZ(l–n)SM,Z
9.3.1.1 Plastic and compact sections d) For rectangular hollow sections and welded
box sections
In the design of members subjected to combined axial
When the section is symmetric about both
force (tension or compression) and bending moment,
the following should be satisfied: axes and without bolt holes

Mti, = M~, (1 -n)/(1 -0.5a,) <MdY

(-4J+(*’h) Mm,,= M,: (1 – n) /(1 – 0.5aW)< M~Z

where

aW=(A-2bt~)/A <0.5
Conservatively, the following equation may also be
a, =(A-2htW)/A <0.5
used under combined axial force and bending moment:
e) Circular hollow tubes without bolt holes
Mn~= 1.04M~ (1–n17) <M~

70
 . ,_,
___ ....__
-

IS 800:2007

9.3.1.3 Semi-compact section with respect to extreme compression

fibre; and
In the absence of high shear force (see 9.2.1), semi-
compact section design is satisfactory under combined v = 0.8, if T and M can vary independently,
axial force and bending, if the maximum longitudinal or otherwise
stress under combined axial force and bending, ~, = 1.0.
satisfies the following criteria: 9.3.2.2 Bending and axial compression
f. ~fy%o Members subjected to combined axial compression and
For cross-section without holes, the above criteria biaxial bending shall satisfy the following interaction
reduces to, relationships:

N ~, ~<lo C~YMY M
:+KY —+K~~— z <1.()
~+mfdy
‘Mdz
–“ liy M,, MdZ
C’~YMY C M
where ;+ 0.6 KY—+KZ ~<1.()
di M,, M~Z
N~, M~Y,M~z are as defined in 9.3.1.1.
where
Table 17 Constants al and CCz
C~Y,Cm, = equivalent uniform moment factor as per
(Clause 9.3.1.1) Table 18;

s] Section al CZ2
P = applied axial compression under factored
No. load;
(1) (2) (3) (4)
MY,M,= maximum factored applied bending
i) I and channel 5n>) 2 moments about y and z-axis of the
ii) Circular tubes 2 2 member, respectively;
iii) Rectanguku’ 1.661 1.66/
tubes (1–1.13rr2)< 6 (1-1 .13n’)<6 P~vP~Z=
.. . design strength under axial compression
iv) Solid rectangles 1.73+ 1.8rr] 1.73+ 1.8n3 as governed by buckling about minor (y)
NOTE.— n =NINA. and major (z) axis respectively;
MdY,Ma, = design bending strength about y (minor)
9.3.2 Overall Member Strength or z (major) axis considering laterally
unsupported length of the cross-section
Members subjected to combined axial force and
(see Section 8);
bending moment shall be checked for overall buckling
failure as given in this section. KY = 1+ (AY– 0.2)nY< 1 + 0.8 nY;
K. = 1 + (AZ– 0.2)nZ< 1+ 0.8 n.; and
9.3.2.1 Bending and axial tension
The reduced effective moment, M.f~, under tension and O.IALTn, 0.1 ny
K~~=
bending calculated as given below, should not exceed 1- (Cm,, - 0.25) 21- (C.,T- 0.25)
the bending strength due to lateral torsional buckling,
where
M~ (see 8.2.2).
nY nZ= ratio of actual applied axial force to the
Me,, = [M– VT Zec/A]s M~ design axial strength for buckling about
the y and z axis, respectively, and
where
c mLT = equivalent uniform moment factor for
M,T= factored applied moment and tension, lateral torsional buckling as per Table 18
respectively: corresponding to the actual moment
A= area of cross-section; gradient between lateral supports against
torsional deformation in the critical
Zec = elastic section modulus of the section
region under consideration.

71
IS 800:2007
s
-$
y
0 u
Al
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WI
‘YJ 0
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0
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e ‘3
C$
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Al
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~ .
0 0
I 0
+
0 VI
m
0“
0
VI VI VI
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VI VI VI
7 0
7
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VJ \“,
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72
 - “------

IS 800:2007

SECTION 10 tightened to develop necessary pretension after

CONNECTIONS welding.

10.1.6 The partial safety factor in the evaluation of

10.1 General
design strength of connections shall be taken as given
10.1.1 This section deals with the design and detailing in Table 5.
requirements for joints between members. Connection
elements consist of components such as cleats, gusset 10.2 Location Details of Fasteners
plates, brackets, connecting plates and connectors such 10.2.1 Clearances for Holes for Fasteners
as rivets, bolts, pins, and welds. The connections in a
structure shall be designed so as to be consistent with Bolts may be located in standard size, over size, short
the assumptions made in the analysis of the structure slotted or long slotted hole.
and comply with the requirements specified in this a) Standard clearance hole — Except where
section. Connections shall be capable of transmitting fitted bolts, bolts in low-clearance or oversize
the calculated design actions. holes are specified, the diameter of standard
10.1.2 Where members are connected to the surface clearance holes for fasteners shall be as given
of a web or the flange of a section, the ability of the in Table 19.
web or the flange to transfer the applied forces locally b) Over size hole — Holes of size larger than the
should be checked and where necessary, local stiffening standard clearance holes, as given in Table
provided. 19 may be used in slip resistant connections
and hold down bolted connections, only
10.1.3 Ease of fabrication and erection should be
where specified, provided the over size holes
considered in Ihe design of connections. Attention
in the outer Ply is covered by a cover plate of
should be paid to clearances necessary for field
sufficiently large size and thickness and
erection, tolerances, tightening of fasteners, welding
having a hole not larger than the standard
procedures, subsequent inspection, surface treatment
clearance hole (and hardened washer in slip
md maintenance.
resistant connections).
10.1.4 The ductility of steel assists the distribution of c) Short and long slots — Slotted holes of size
forces generated within a joint. Effects of residual larger than the standard clearance hole, as
stresses and stresses due to tightening of fasteners and given in Table 19 maybe used in slip resistant
normal tolerances of fit-up need not therefore be connections and hold down bolted
considered in connection design, provided ductile connections, only where specified, provided
behaviour is ensured. the over size holes in the outer ply is covered
by a cover plate of sufficiently large size and
10.1.5 In general, use of different forms of fasteners
thickness and having a hole of size not larger
to transfer the same force shall be avoided. However,
than the standard clearance hole (and
when different forms of fmteners are used to carry a
hardened washer in slip resistant connection).
shear load or when welding and fasteners are
combined, then one form of fastener shall be normally 10.2.2 Minimum Spacing
designed to carry the total load. Nevertheless, fully
The distance between centre of fasteners shall not be
tensioned friction grip bolts may be designed to share
less than 2.5 times the nominal diameter of the fastener.
the ioad with welding, provided the bolts are fully

Table 19 Clearances for Fastener Holes

(Clause 10.2.1)

SI Nominal Size of Size of the Hole= Nominal Diameter of the Fastener+ Clearances
No. Fastener, d mm

Standard Clearance in Cher Size Clearance in the Length of the Slot

Diameter and Width Clearance in Diameter
of slot < Short Slot Long Slot >
(1) p) (3) (4) (5) (6)
i) 12– 14 1.0 3.0 4.0 2.5 d
ii) 16–22 2.0 4.0 6.0 2.5 d
iii) 24 2.0 6.0 8.0 2.5 d
iv) Largerthan 24 3.0 8.0 10.0 2.5 d

73
IS 800:2007

10.2.3 Muxlmum Spacing not apply to fasteners interconnecting the components

of back to back tension members. Where the members
10.2.3.1 The distance between the centres of any two
are exposed to corrosive influences, the maximum edge
adjacent fasteners shall not exceed 32t or 300 mm,
distance shall not exceed 40 mm plus 4t, where t is the
whichever is less, where tis the thickness of the thinner
thickness of thinner connected plate.
plate.
10.2.5 Tacking Fasteners
10.2.3.2 The distance between the centres of two
adjacent fasteners (pitch) in a line lying in the direction 10.2.5.1 In case of members covered under 10.2.4.3,
of stress, sh~ll not exceed 16t or 200 mm, whichever when the maximum distance between centres of two
is less, in tension members and 12t or 20() mm, adjacent fasteners as specified in 10.2.4.3 is exceeded,
whichever is less, in compression members; where r is tacking fasteners not subjected to calculated stress shall
the thickness of the thinner plate. In the case of be used.
compression members wherein forces are transferred
10.2.5.2 Tacking fasteners shall have spacing in a line
through butting faces, this distance shall not exceed
not exceeding 32 times the thickness of the thinner
4.5 times the diameter of the fasteners for a distance
outside plate or 300 mm, whichever is less. Where the
equal to 1.5 times the width of the member from the
plates are exposed to the weather, the spacing in line
butting faces.
shall not exceed 16 times the thickness of the thinner
10.2.3.3 The distance between the centres of any two outside plale or 200 mm, whichever is less. In both
consecutive fasteners in a line adjacent and parallel to cases, the distance between the lines of fasteners shall
an edge of an outside plate shall not exceed 100 mm not be greater than the respective pitches.
plus 4t or 200 mm, whichever is less, in compression
10.2.5.3 All the requirements specified in 10.2.5.2 shall
and tension members; where t is the thickness of the
generally apply to compression members, subject to
thinner outside plate.
the stipulations in Section 7 affecting the design and
10.2.3.4 When fasteners are staggered at equal intervals construction of compression members.
and the gauge does not exceed 75 mm, the spacing
10.2.5.4 In tension members (see Section 6) composed
specified in 10.2.3.2 and 10.2.3.3 between centres of
of two flats, angles, channels or tees in contact back to
fasteners may be increased by 50 percent, subject to
back or separated back to back by a distance not
the maximum spacing specified in 10.2.3.1.
exceeding the aggregate thickness of the connected parts,
10.2.4 Edge and End Distances tacking fasteners with solid distance pieces shall be
provided at a spacing in line not exceeding 1000 mm.
10.2.4.1 The edge distance is the distance at right angles
to the direction of stress from the centre of a hole to 10.2.5.5 For compression members covered in
the adjacent edge. The end distance is the distance in Section 7, tack~ng fasteners in a line shall be spaced at
the direction of stress from the centre of a hole to the a distance not exceeding 600 mm.
end of the element.
10.2.6 Countersank Heads
In slotted holes, the edge and end distances should be
For countersunk heads, one-half of the depth of the
measured from the edge or end of the material to the
countersinking shall be neglected in calculating the
centre of its end radius or the centre line of the slot,
length of the fastener in bearing in accordance
whichever is smaller. In oversize holes, the edge and
with 10.3.3. For fasteners in tension having
end distances should be taken as the distance from the
countersunk heads, the tensile strength shall be reduced
relevant edge/end plus half the diameter of the standard
by 33.3 percent. No reduction is required to be made
clearance hole corresponding to the fastener, less the
in shear strength calculations.
nominal diameter of the oversize hole.

10.2.4.2 The minimum edge and end distances from 10.3 Bewing Type Bolts
the centre of any hole to the nearest edge of a plate 10.3.1 Effective Areas of Bolts
shall not be less than 1.7 times the hole diameter in
case of sheared or hand-flame cut edges; and 1.5 times 10.3.1.1 Since threads can occur in the shear plane,
the hole diameter in case of rolled, machine-flame cut, the area .4Cfor resisting shear should normally be taken
sawn and planed edges. as the net tensile stress area, An of the bolts. For bolts
where the net tensile stress area is not defined, An shall
10.2.4.3 The maximum edge distance to the nearest be taken as the area at the root of the threads.
line of fasteners from an edge of any un-stiffened part
should not exceed 12 tE, where c = (250/’)”2 and t is 10.3.1.2 Where it can be shown that the threads do not
the thickness of the thinner outer plate. This would occur in the shear plane, A~ may be taken as the cross
section area, A, at the shank.

74
 IS 800:2007

10.3.1.3 In the calculation of thread length, allowance the connected plates) exceeds 5 times the diameter, d
should be made for tolerance and thread run off. of the bolts, the design shear capacity shall be reduced
by a factor ~1~,given by:
10.3.2 A bolt subjected to a factored shear force ( VJ
shall satisfy the condition ~,, = 8 d /(3 d+ 1,) = 8 /(3+1,/d)

v... = Vdb ~i, shall not be more than f$j given in 10.3.3.1. The
grip length, 1~shall in no case be greater than 8d.
where V~~is the design strength of the bolt taken as the
smaller of the value as governed by shear, V~,~ 10.3.3.3 Packing plates
(see 10.3.3) and bearing, V,P~(see 10.3.4).
The design shear capacity of bolts carrying shear
10.3.3 Shear Capacity of Bolt through a packing plate in excess of 6 mm shall be
decreased by a factor, ~P~given by:
The design strength of the bolt, V~,~as governed shear
strength is given by: ~,, =(1 -0.0125 tpk)

v dstr = ‘nsb 1 ~mb where

where tP~ = thickness of the thicker packing, in mm.

Vn,b = nominal shear capacity of a bolt, 10.3.4 Bearing Capacity of the Bolt
calculated as follows: The design bearing strength of a bolt on any plate, V~P~
as governed by bearing is given by:
v],, =@ %)+% ‘%,)

where
where

~ = uitimate tensile strength of a bolt;

v npb = nominal bearing strength of a bolt
= 2.5 k~d tfu
nn = number of shear planes with threads
intercepting the shear plane; where

n, = number of shear planes without threads e P

intercepting the shear plane; —–0.25, $, 1.0;
‘b ‘s ‘mailer ‘f ~’ 3d0 u
A,b = nominal plain shank area of the bolt; and
Anb = net shear area of the bolt at threads, may e, p = end and pitch distances of the fastener
be taken as the area corresponding to along bearing direction;
root diameter at the thread. dO = diameter of the hole;
10.3.3.1 L.ongjoints
fub,it = Ultimate tensile stress of the bolt and the
When the length of the joint, lj of a splice or end ultimate tensile stress of the plate,
connection in a compression or tension element respectively;
containing more than two bolts (that is the distmce d = nominal diameter of the bolt; and
between the first and last rows of bolts in the joint, [ = summation of the thicknesses of the
measured in the direction of the load tmnsfer) exceeds connected plates experiencing bearing
15a!in the direction of load, the nominal shear capacity stress in the same direction, or if the bolts
(see 10.3.2), V~~shall be reduced by the factor ~lj, given are countersunk, the thickness of the
by: plate minus one half of the depth of
countersinking.
Plj = 1.075-1, /(200 ~) but 075<Pli<10

The bearing resistance (in the direction normal to the

= 1.075- o.oo5(lj /d)
slots in slotted holes) of bolts in holes other than
where standard clearance holes may be reduced by
multiplying the bearing resistance obtained as above,
d = Nominal diameter of the fastener.
V~p~,by the factors given below:
NOTE—This provisiondoes not apply when the distribution
of shear over the length of joint is uniform, as in the connection a) Over size and short slotted holes – 0.7, and
of web of a section to the flanges.
b) Long slotted holes – 0.5.
10.3.3.2 Large grip lengths
NOTE — The block shear of the edge distance due to
When the grip length, 1~(equal to the total thickness of bearing force may be checked as given in 6.4.

75
IS 800:2007

10.3.5 Tension Capacity 0 be limited, a bolt subjected only to a factored design

jhe~ force, V,~in the interface of connections at which
Aboltsubjected toafactored tensile force, Th shall
$Iip cannot be tolerated, shall satisfy the following:
satisfy:
V,f < Vd,f
Th < T~h
where
where
Vd,f = Vn,f/ ymf
T~b ‘Tnb\)’mb
Vn,~ = nominal shear capacity of a bolt as
T,,~ = nominal tensile capacity of the bolt,
governed by slip for friction type
calculated as:
connection, calculated as follows:
f).90~u~ A,, < fYb ASb (~mb f %())
v~,f = t%n. Kh F.
where
where
& = ultimate tensile stress of the bolt,
Pf = coefficient of friction (slip factor) as
~,b = yield stress of the bolt, specified in Table 20 @~= 0.55),
A. = net tensile stress area as specified in the ne = number of effective interfaces offering
appropriate Indian Standard (for bolts frictional resistance to s~ip,
where the tensile stress area is not
K~ = 1.0 for fasteners in clearance hoIes,
defined, A,, shall be taken as the area at
the bottom of the threads), and = 0.85 for fasteners in oversized and short
slotted holes and for fasteners in long
A,~ = shank area of the bolt.
slotted holes loaded perpendicular to the
10.3.6 Bolt Subjected to Combined Sheat- and Tension slot,
A bolt required to resist both design shear force (V,~) = 0.7 for fasteners in long slotted holes
and design tensile force (TJ at the same time shall loaded parallel to the slot,
satisfy: y~~ = 1.10 (if slip resistance is designed at
service load),
= 1.25 (if slip resistance is designed at
ultimate load),
F. = minimum bolt tension (proof load) at
where installation and may be taken as
V,b = factored shear force acting on the bolt, A.bfO>
vdb = design shear capacity (see 10.3.2), A nh = net area of the bolt at threads, and

Tb = factored tensile force acting on the bolt, and fO = proof stress (= 0.70~ub).
T~b . design tension capacity (see 10.3.5). NOTE — Vn.may be evaluated at a service load or ultimate
load using appropriatepartial safety factors, depending upon
10.4 Friction Grip Type Bolting whether slip resistance is required at service load or ultimate
load.
10.4.1 In friction grip type bolting, initial pretension
in bolt (usually high strength) develops clamping force 10.4.3.1 Long joints
at the interfaces of elements being joined. The frictional The provision for the long joints in 10.3.3.1 shall apply
resistance to slip between the plate surfaces subjected to friction grip connections also.
to clamping force opposes slip due to externally applied
shear. Friction grip type bolts and nuts shall conform 10.4.4 Capacity after slipping
to IS 3757. Their installation procedures shall conform When friction type bolts are designed not to slip only
to IS 4000. under service loads, the design capacity at ultimate load
10.4.2 Where slip between bolted plates cannot be may be calculated as per bearing type connection
tolerated at working loads (slip critical connections), (see 10.3.2 and 10.3.3).
the requirements of 10.4.3 shall be satisfied. However, NOTE — The block shear resistance of the edge distance due
at ultimate loads, the requirements of 10.4.4 shall be to bearing force may be checked as given in 6.4.
satisfied by all connections.
10.4.5 Tension Resistance
10.4.3 Slip Resistance
A friction bolt subjected to a factored tension force (Tf )
Design for friction type bolting in which slip is required shall satisfy:

76
 IS 800:2007

Tf < Tdf where

where V,f = applied factored shear at design load,

Tdf = Tnf1 k V~f = design shear strength,

Tn~ = nominal tensile strength of the friction bolt, T~ = externally applied factored tension at
calculated as: design load, and

0.9$U~An ~~YbA,b(y~ll %) T~~ = design tension strength.

where 10.4.7 Where prying force, Q as illustrated in Fig. 16

is significant, it shall be calculated as given below and
f“, = ultimate tensile stress of the bolt;
added to the tension in the bolt.
A. = net tensile stress area as specified in
various parts of IS 1367 (for bolts where
the tensile stress area is not defined, A. f2=$[Te-fiqf0bet4]
e 271, 1;
shall be taken as the area at the root of
the threads);
where
A,, = shank area of the bolt; and
y~~ = partial factor of safety. 1, = distance from the bolt centreline to the toe
of the fillet weld or to half the root radius
Table 20 ~pical Average Values for Coefficient for a rolled section,
of Friction (pf)
le = distance between prying force and bolt
(Clause 10.4.3) centreline and is the minimum
of either the end distance or the value given
SI Treatment of Surface Coefficient
by:
No. of Friction,

(1) (2) &

O Surfacesnot treated 0.20

ii) Surfacesblastedwith short or grit with 0.50
any looserust removed,no pitting where
iii) Surfacesblastedwith shot or grit and 0.10
hot-dipgalvanized 2 for non pre-tensioned bolt and 1 for pre-
P=
iv) Surfaces blasted with shot or grit and 0.25
spray+netallizedwith zinc (thickness tensioned bolt,
50-70 jan) = 1.5,
~
v) Surfacesblastedwith shot or grit and 0.30
paintedwith ethylzincsilicatecoat b, = effective width of flange per pair of bolts,
(thickness30-60 ~)
vi) Sandblastedsurface,atter light rusting 0.52 f. = proof stress in consistent units, and
vii) Surfacesblasted with shot or grit and 0.30 t = thickness of the end plate.
painted with ethylzinc silicate coat
(thickness60-80 W)
0.30 2Te
viii) Surfacesblasted with shot or grit and t
painted with alcalizinc silicate coat

II
(thickness60-80 ,mn)
ix) Surface blasted with shot or grit and 0.50
spray metallized with aluminium
(thickness>50 ,mrr)
x) Clean mill scale 0.33
xi) Sand blasted surface 0.48
xii) Red lead painted surface 0.1

10.4.6 Combined Shear and Tension

B
Bolts in a connection for which slip in the serviceability
limit state shall be limited, which are subjected to a
tension force, T and shear force, V, shall satisfy:

I TC+Q

FIG. 16 COMBINEDPRYINGFORCEANDTENSION

77
IS 800:2007

10.5 Welds and Welding shall not be less than 3 mm and shall generally not exceed
0.7?, or 1.Ot under special circumstances, where t is the
10.5.1 General
thickness of the thinner plate of elements being welded.
Requirements of welds and welding shall conform to
IS 816 and IS 9595, as appropriate. Table 21 Minimum Size of First Rtm or of a
Single Run Fillet Weld
10.5.1.1 End returns
(Clause 10.5.2.3)
Fillet welds terminating at the ends or sides of parts
should be returned continuously around the corners SI Thickness of Thicker Part Minimum Size
for a distance of not less than twice the size of the No. mm mm
/. —_. — —_
weld, unless it is impractical to do so. This is
Over Up to and
particularly important on the tension end of parts trrcluding
carrying bending loads. (1) (2) (3) (4)

10.5.1.2 Lap joint i) – 10 3

ii) 10 20 5
In the case of lap joints, the minimum lap should not iii) 20 32 6
iv) 32 50 8 of first run
be less than four times the thickness of the thinner part 10 for minimum size of
joined or 40 mm, whichever is more. Single end fillet weld
should be used only when lapped parts are restrained NOTES
1 When the minimum size of the fillet weld given in the table
from openings. When end of an element is connected
is greater than the thickness of the thhner part, the minimum
only by parallel longitudinal fillet welds, the length of size of the weld should be equal to the thickness of the thinner
the weld along either edge should not be less than the part. The thicker part shall be adequately preheated to prevent
transverse spacing between longitudinal welds. cracking of the weld.
2 Where the thicker part is more than 50 mm thick, special
10.5.1.3 A single fillet weld should not be subjected to precautions like pre-heating should be taken.
moment about the longitudinal axis of the weld.
10.5.3.2 For the purpose of stress calculation in fillet
10.5.2 Size of Weld
welds joining faces inclined to each other, the effective
10.5.2.1 The size of normal fillets shall be taken as the throat thickness shall be taken as K times the fillet size,
minimum weld leg size. For deep penetration welds, where K is a constant, depending upon the angle
where the depth of penetration beyond the root run is between fusion faces, as given in Table 22.
a minimum of 2.4 mm, the size of the fillet should be
10.5.3.3 The effective throat thickness of a complete
taken as the minimum leg size plus 2.4 mm.
penetration butt weld shall be taken as the thickness of
10.5.2.2 For fillet welds made by semi-automatic or the thinner part joined, and that of an incomplete
automatic processes, where the depth of penetration is penetration butt weld shall be taken as the minimum
considerably in excess of 2.4 mm, the size shall be thickness of the weld metal common to the parts joined,
taken considering actual depth of penetration subject excluding reinforcements.
to agreement between the purchaser and the contractor. 10.5.4 Effective Length’or Area of Weld
10.5.2.3 The size of fillet welds shall not be less than 10.5.4.1 The effective length of fiilet weld shall be
3 mm. The minimum size of the first run or of a single taken as only that length which is of the specified size
run fillet weld shall be as given in Table 21, to avoid and required throat thickness, In practice the actual
the risk of cracking in the absence of preheating. length of weld is made of the effective length shown
in drawing plus two times the weld size, but not less
10.5.2.4 The size of butt weld shall be specified by the
than four times the size of the weld.
effective throat thickness.
10.5.4.2 The effective length of butt weld shall be taken
10.5.3 Effective Throat Thickness
as the length of the continuous ftdl size weld, but not
10.5.3.1 The effective throat thickness of a fillet weld less than four times the size of the weld.

Table 22 Values of K for Different Angles Between Fusion Faces

(Clause 10.5.3.2)

Angle Between Fusion Faces 60°–900 91”–100” IOI”--1O6” 1070–113° I 14“–120°

Constant, K 0.70 0.65 0.60 0.55 0.50

78
 —,,.

IS 800:2007

10.5.4.3 The effective area of a plug weld shall be 10.5.7.1.3 Slot or plug welds
considered as the nominal area of the hole in the plane
The design shear stress on slot or plug welds shall be
of the faying surface. These welds shall not be designed
as per 10.5.7.1.1.
to carry stresses.
10.5.7.2 Site welds
10.5.4.4 If the maximum length /j of the side welds
transferring shear along its length exceeds 150 times The design strength in shear and tension for site welds
the throat size of the weld, tt, the reduction in weld made during erection of structural members shall be
strength as per the long joint (see 10.5.7.3) should be calculated according to 10.5.7.1 but using a partial
considered. For flange to web connection, where the safety factor y~Wof 1.5.
welds are loaded for the full length, the above limitation
10.5.7.3 Long joints
would not apply.
When the length of the welded joint, lj of a splice or
10.5.5 Intermittent Welds
end connection in a compression or tension element is
10.5.5.1 Unless otherwise specified, the intermittent greater than 150 t,, the design capacity of weld
fillet welding shall have an effective length of not (see 10.5.7.1.1), fwd shall be reduced by the factor
less than four times the weld size, with a minimum
of 40 mm. 0.21.
Plw=l.2---#o.o
10.5.5.2 The clear spacing between the effective lengths [
of intermittent fillet weld shall not exceed 12 and 16
where
times the thickness of thinner plate joined, for
compression and tension joint respectively, and in no lj = length of the joint in the direction of the
case be more than 200 mm. force transfer, and

10.5.5.3 Unless otherwise specified, the intermittent t, = throat size of the weld.
butt weld shall have an effective length of not less than
four times the weld size and the longitudinal space 10.5.8 Fillet Weld Applied to the Edge of a Plate or
between the effective length of welds shall not be more Section
than 16 times the thickness of the thinner part joined. 10.5.8.1 Where a fillet weld is applied to the square
The intermittent welds shall not be used in positions edge of a part, the specified size of the weld should
subject to dynamic, repetitive and alternating stresses. generally beat least 1.5 mm less than the edge thickness
10.5.6 Weld Types and Quality in order to avoid washing down of the exposed arris
(see Fig. 17A).
For the purpose of this code, weld shall be fillet, butt,
10.5.8.2 Where the fillet weld is applied to the rounded
slot or plug or compound welds. Welding electrodes
toe of a rolled section, the specified size of the weld
shall conform to 1S 814.
should generally not exceed 3/4 of the thickness of the
10.5.7 Design Stresses in Welds section at the toe (see Fig. 17B).

10.5.7.1 Shop welds 10.5.8.3 Where the size specified for a fillet weld is
such that the parent metal will not project beyond the
10.5.7.1.1 Fillet welds
weld, no melting of the outer cover or covers shall be
Design strength of a fillet weld, ~W~shall be based on allowed to occur to such an extent as to reduce the
its throat area and shall be given by: throat thickness (see Fig. 18).

fwd ‘f.. t ?’mw 10.5.8.4 When fillet welds are applied to the edges of
where a plate, or section in members subject to dynamic
loading, the fillet weld shall be of full size with its leg
f.. = f,/&* length equal to the thickness of the plate or section,
with the limitations specified in 10.5.8.3.
fu = smaller of the ultimate stress of the weld
or of the parent metal, and 10.5.8.5 End fillet weld, normal to the direction of force
shall be of unequal size with a throat thickness not
y~~ = partial safety factor (see Table 5).
less than 0.5t, where t is the thickness of the part, as
10.5.7.1,2 Butt welds shown in Fig. 19. The difference in thickness of the
welds shall be negotiated at a uniform slope.
Butt welds shall be treated as parent metal with a
thickness equal to the throat thickness, and the stresses 10.5.9 Stresses Due to Individual Forces
shall not exceed those permitted in the parent metal. When subjected to either compressive or tensile or

79
IS 800:2007

1.5 mm

17A 17B

FIG. 17 FILLETWELDS ON SQUAREEDGE OF PLATEOR ROUNDTOE OF ROLLEDSECTION

18A Desirable 18B Acceptable because of 18C Not Acceptable because of

Full Throat Thickness Reduced Throat Thickness

Fm. 18 FULL SIZE FILLETW ELDAPPLIIZDTOTHEEDGE OF A PLATEOR SECTION

shear force alone, the stress in the weld is given by: not be done fo~

a) side fillet welds joining cover plates and

flange plates, and
faorq=~
b) fillet welds where sum of normal and shear
where stresses does not exceed~W~ (see 10.5.7.1.1).

calculated normal stress due to axial force, 10.5.10.2 Butt welds

L=
in N/mm*; 10.5.10.2.1 Check for the combination of stresses in
q = shear stress, in N/mm*; butt welds need not be carried out provided that
P= force transmitted (axial force Nor the shear a) butt welds are axially loaded, and
force Q);
b) in single and double bevel welds the sum of
t, = effective throat thickness of weld, in mm; normal and shear stresses does not exceed the
and design normal stress, and the shear stress does
lW = effective length of weld, in mm. not exceed 50 percent of the design shear
stress.
10.5.10 Combination of Stresses
10.5.10.2.2 Combined bearing, bending and shear
10.5.10.1 Fillet welds Where bearing stress, fb, is combined with bending
10.5.10.1.1 When subjected to a combination of normal (tensile or compressive), fb and shear stresses, q under
and shear stress, the equivalent stress fe shall satisfy the most unfavorable conditions of loading in butt
the following: welds, the equivalent stress, ~, as obtained from the
following formula, shall not exceed the values allowed
for the parent metal:

& = Jf; +f; +f, fbr+%’

where
where
L= normal stresses, compression or tension, due
to axial force or bending moment L= equivalent stress;
(see 10.5.9), and fb = calculated stress due to bending, in N/mmz;

q = shear stress due to shear force or tension (see fb, = calculated stress due to bearing, in N/mm*;
10.5.9). and
10.5.10.1.2 Check for the combination of stresses need q = shear stress, in N/mm*.

80
 IS 800:2007

CHAMFER

1
h

ri

h:b = 1:2 or Flatter

FORCE FORCE

FIG, 19 END FILLET WELD NORMAL TO DIRECTION OR FORCE

10.5.11 Where a packing is welded between two d) Connection elements shall remain stable
members and is less than 6 mm thick, or is too thin to under the design action effects and
allo”w provision of adequate welds or to prevent deformations.
buckIing, the packing shall be trimmed flush with the
10.6.1 Connections can be classified as rigid, semi-rigid
edges of the element subject to the design action and
and flexible for the purpose of analysis and design as
the size of the welds along the edges shall be increased
per the recommendation in Annex F. Connections with
over the required size by an amount equal to the
sut%cient rotational stiffness maybe considered as rigid.
thickness of the packing. Otherwise, the packing shall
Examples of rigid connections include flush end-plate
extend beyond the edges and shall be fillet welded to
connection and extended end-plate connections.
the pieces between which it is fitted.
Connections with negligible rotational stiffness may be
10.6 Design of Connections considered as flexible (pinned). Examples of flexible
connections include single and double web angle
Each element in a connection shall be designed so that connections and header plate connections. Where a
the structure is capable of resisting the design actions. connection cannot be classified as either rigid or flexible,
Connections and adjacent regions of the members shall it shall be assumed to be semi-rigid. Examples of semi-
be designed by distributing the design action effects rigid connections include top and seat angle connection
such that the following requirements are satisfied: and top and seat angle with single/double web angles.
a) Design action effects distributed to various 10.6.2 Design shall be on the basis of any rational
elements shall be in equilibrium with the method supported by experimental evidence. Residual
design action effects on the connection, stresses due to installation of bolts or welding normaily
b) Required deformations in the elements of the need not be considered in statically loaded structures,
connections are within their deformations Connections in cyclically loaded structures shall be
capacities, designed considering fatigue as given in Section 13.
c) All elements in the connections and the For earthquake load combinations, the connections
adjacent areas of members shall be capable shall be designed to withstand the calculated design
of resisting the design action effects acting action effects and exhibit required ductility as specified
on them, and in Section 12.

81