Authors
Abstract
A nonlinear, layered, finite element model for predicting the time dependent
behavior of reinforced concrete slabs under sustained transverse loading is
presented. The effects of biaxial creep and shrinkage are considered by using
the provisions of ACI Committee 209. Both elastic- perfectly plastic and strain
hardening plasticity approach have been employed to model the compressive
behavior of the concrete. The yield condition is formulated in terms of twostress
invariants. The movement of the subsequent loading surfaces is
controlled by the hardening rule, which is extrapolated from the uniaxial
stress-strain relationship defined by a parabolic function. Concrete crushing is
a strain controlled phenomenon, which is monitored by a fracture surface
similar to the yield surface. A smeared fixed crack approach is used to model
the behavior of the cracked concrete, coupled with a tensile strength criterion
to predict crack initiation. An attention is given also to the post-cracking shear
strength. The steel is considered either as an elastic perfectly plastic material
or as an elastic-plastic material with linear strain hardening. Steel
reinforcement is assumed to have similar tensile and compressive stress-strain
relationship. A computer program coded in FORTRAN77 language is written
to implement the present study. This program is arranged to give a complete
listing of stresses and deformations in every concrete or steel layer. Several
examples for which experimental results are available are analyzed, using the
proposed model .The comparison showed very good agreement especially for
the maximum deflection, the different about 1%.
)
