Non-Linear Finite Element Analysis of Concrete Structures by malj


									  Non-Linear Finite Element Analysis of RC Bridge Columns
            using the Softened Membrane Model

      T Ravi S Mullapudi, PhD Candidate, University of Houston, Texas, USA
     Ashraf Ayoub, PhD, Associate Professor, University of Houston, Texas, USA


This paper presents a non-linear finite element beam-column model applied to
reinforced concrete bridge columns using a new set of constitutive laws based on
the fixed angle softened membrane model. These newly developed constitutive
laws can predict the concrete contribution, which is produced by the shear
resistance of concrete along the initial crack direction. A computer code was
developed specifically for application to reinforced concrete structures subjected
to both monotonic and cyclic loads. The constitutive relationships of the RC
element were developed based on the smear behavior of cracked continuous
orthotropic material assumption, with the inclusion of Poisson effect (mutual
effect of the two normal strains). The concrete model accounts for the biaxial state
of stress in the directions of orthotropy, in addition to degradation under reversed
cyclic loading. The shear mechanism along the beam is modeled by using
Timoshenko beam approach Transverse strains are internal variables determined
by imposing equilibrium between concrete and vertical steel stirrups. Element
forces are obtained by performing equilibrium based numerical integration on
section axial, flexural and shear behaviors along the length of the element. The
predictions made by the new element proved to be in good agreement with the
experimental results.

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