Arsc 443 Architectural Structures

ARSC 443 ARCHITECTURAL
STRUCTRURES
ENGR. JOEVANNIE EMMANUEL C. LUMAGAS
INSTRUCTOR
CIVIL ENGINEERING DEPARTMENT TECHNOLOGICAL INSTITUTE OF THE PHILIPPINES - MANILA ARCHITECTURAL STRUCTURES
Welcome, TIPians!
Heads Up! Future Architects!
CIVIL ENGINEERING DEPARTMENT TECHNOLOGICAL INSTITUTE OF THE PHILIPPINES - MANILA STEEL AND TIMBER DESIGN
FUNDAMENTAL ASSUMPTIONS FOR
REINFORCED CONCRETE DESIGN
INTENDED LEARNING OUTCOMES
At the end of the session the students should be able to:
1.Learn and understand the fundamental concepts of

Reinforced Concrete Design
Design – the determination of the general
shape and all specific dimensions of a
particular structure so that it will perform
the function for which it is created and
will safely withstand the influences that
will act on it throughout its useful life.
•The internal forces, such as bending
moments, shear forces, and normal and
shear stresses, at any section of a member
are in equilibrium with the effects of the
external loads at that section.
•The strain in an embedded reinforcing bar is
the same as that of the surrounding concrete.
•Cross-sections that were plane prior to
loading continue to be plane in the
member under load.
•Concrete is assumed not capable of
resisting any tension stress.
•The theory is based on the actual-
stress-strain relationship and strength
properties of the two constituent
materials.
DESIGN ASSUMPTIONS
Equilibrium of Forces and
Compatibility of strains
Computation of strength of a member or
a cross-section by the Strength Design
Method requires that two basic
conditions be satisfied: (1) Static
equilibrium and (2) Compatibility of
strain.
The first condition requires that the compressive
and tensile forces acting on the cross-section at
“ultimate” strength be in equilibrium, and the
second condition requires that compatibility
between the strains in the concrete and the
reinforcement at “ultimate” condition must also
be satisfied within the design assumptions
permitted by the code.
Design Assumption #1
Strain in reinforcement and
concrete shall be assumed directly
proportional to the distance from
the neutral axis.
In other words, plane sections

normal to the axis of bending are
assumed to remain plane after
bending.
The maximum usable strain at
extreme concrete compression fiber
shall be assumed equal to εu = 0.003.
Stress in reinforcement fs shall be
taken as Es times strain εs. for strain
greater than fy/Es, stress in
reinforcement shall be considered
independent of strain and equal to fy.
The force developed in the tensile or
compressive reinforcement is a function of the
strain in the reinforcement εs, such that:
when εs ≤ εy (yield strain):

fs = Es εs
As fs = As Es εs
when εs ≥ εy:
fs = Es εy = fy
As fs = As fy
where εs is the value from the strain diagram at the
location of reinforcement. For design, the modulus of
elasticity of steel reinforcement, Es, is taken as 200,000
MPa (29, 000, 000 psi).
The tensile strength of concrete shall be
neglected in flexural calculations of
reinforced concrete.
The tensile strength of concrete in flexure,

known as the modulus of rupture, is a more
variable property than the compressive
strength and is about 8% to 12% of the
compressive strength. The generally
acceptable value is 7.5 for normal-weight
concrete.
The relationship between compressive stress
distribution and concrete strain shall be assumed to
be rectangular, trapezoidal, parabolic, or any shape
that results in the prediction of strength in substantial
agreement with the results of a comprehensive test.
Requirements of Design Assumption #5
may be considered satisfied by an
equivalent rectangular concrete stress
distribution defined as follows: A concrete
stress of 0.85f’c shall be assumed uniformly
distributed over an equivalent compression
zone bounded by edges of the cross-section
and a straight line located parallel to the
neutral axis at a distance a=β1c from the
fiber of maximum compressive strain.
HI! WELCOME TO ARSC 443 ARCHITECTURAL STRUCTURES.
Good day class, read module 2 and check the
following activities in your respective Canvas
LMS.
Note: For questions and concerns, please

message here in the public chat. Please check announcements regarding Honor
Live Discussion on Thursday, October 13, 2022 Pledges and reply to the post.

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ARSC 443 ARCHITECTURAL

1.Learn and understand the fundamental concepts of

In other words, plane sections

when εs ≤ εy (yield strain):

The tensile strength of concrete in flexure,

Note: For questions and concerns, please

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