NONLINEAR FINITE-ELEMENT ANALYSIS OF RC SHEAR PANELS AND WALLS

In the assessment of existing reinforced concrete structures, finite-e lement analysis plays an important role, particularly in regard to the evaluation of critical regions, regions with special detailing, or re gions of stress concentration. A popular class of concrete model uses an orthotropic constitutive relation in which the directions of orthot ropy are the principal directions of total strain. Since these directi ons change during the load-displacement response, such an approach is known as a rotating crack model. The models proposed to date differ in the description of the biaxial failure envelope, the uniaxial equival ent stress-strain relation, Poisson ratio, and the tension-compression behavior. This paper describes the implementation of an orthotropic c oncrete constitutive model in the finite-element analysis of reinforce d concrete members. The emphasis of the paper is on the evaluation of the effect of orthotropic model parameters on the monotonic lead-displ acement relation of shear panels and walls under different stress stat es. The ability of the orthotropic concrete material model to assess f ailure mode, ultimate strength, and load-deformation behavior of this type of structural element is evaluated by correlation studies with av ailable experimental data.