Distributed plasticity models for the seismic response of reinforced concrete shear walls

The paper tackles the nonlinear modeling of seismic resistant reinforced-concrete walls. Two different models are built in OpenSees, both taking into account the mechanical nonlinearity distributed along the wall element. The former, referred to as MVLEM (Multiple Vertical Line Element Model), is a two-dimensional model able to reproduce both the flexural and the shear behavior of the wall, although assumed as uncoupled. The wall is simulated by means of two horizontal rigid beams, connected by several vertical uniaxial springs with proper stiffness, absorbing the bending moment of the wall. More-over, a uniaxial horizontal spring is located along the height of the element in order to provide the shear deformability. The latter model is a fiber model, with a force-based formulation. The element is discre-tized in several control cross sections, each of which is further divided in fibers, according to the struc-tural materials and accounting for their nonlinearity. This approach is not able to reproduce the shear deformability of the wall. The effectiveness of the investigated modeling approaches is assessed by means of an application to a case-study structure, consisting in a five story RC frame. Nonlinear time histories analyses, considering properly scaled real floor motions, are performed on both the models. The structural response of both the models is assessed and compared; advantages and shortcomings deriving by the use of each implemented models are reported and commented, providing useful insights for the modeling of RC walls.