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1.054/1.541 Mechanics and Design of Concrete Structures
Spring 2004
Prof. Oral Buyukozturk
1 / 6
Massachusetts Institute of Technology
1.054/1.541 Mechanics and Design of Concrete Structures (309)
Outline 8
Biaxial Bending
±
R/C columns under biaxial bending
o
The problem of columns under biaxial bending is nonlinear and the
number of unknowns is large. For any defined column the problem
may be expressed as:
()
,,
θε
=
xy
c
Pe e
f c
where
f
= a nonlinear function of the variables that can be derived
from the equilibrium equations and geometry of any given
column section and the stressstrain curves of the
materials,
P
= axial load,
,
ee
= eccentricities measured parallel to x and y axes,
respectively,
θ
= inclination of neutral axis,
c
= depth of neutral axis measured from extreme compressive
fiber, and
ε
c
= failure strain of concrete in compression.
o
A number of approximate methods which are based on simplifying
assumptions have been developed. However, for certain situations, the
simplifying assumptions may lead to inaccurate results, and the use
of presently available design charts is often limited.
o
The use of computers to solve this problem with improved accuracy
has been based upon iterative analysis of trial sections until a
satisfactory result is achieved.
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View Full Document1.054/1.541 Mechanics and Design of Concrete Structures
Spring 2004
Prof. Oral Buyukozturk
Outline 8
o
Apart from these considerations, the design process should not be
limited to a purely numerical evaluation of the loads, stresses, and
strains involved; basic design issues, such as seismic requirements,
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