Comparing the Nonlinear Behaviors of Steel and Concrete Link Beams in Coupled Shear Walls System by Finite Element Analysis

Abstract

Regarding the role of link beams in the seismic behavior of coupled shear walls, in this study, at first a pre-designed concrete link beam of a coupled shear walls system, tested previusly under cyclic loading, has been analyzed by Finite Element Modeling (FEM). Then it has been substituted by a steel link beam, and the analyses have been repeated to find out the differences between the hysteretic behavior of the concrete link beam with that of the steel link beam, designed with the same loading. In the verified FEM 8-node elastoplastic solid elements have been used. For the concrete link beams the material has been of ‘concrete damage plasticity’ type, and for the steel link beams the multi-linear elastoplastic material model has been used. The steel reinforcement bars in concrete elements have been modeled as ‘truss’ element. The steel link beams have been considered once without stiffeners and once with them to see how they improve its behavior. The embedded length of the steel link beams in the concrete walls has been considered long enough to be able to assume that no sliding occurs between the steel beam and its surrounding concrete. Numerical results show that in case of steel link beams the hysteretic loops does not show any pinching effect, and therefore these link beams are better in seismic energy absorption. The amount of energy absorption can be more than 3 times in comparison with the concrete link beams. Using stiffeners in the steel link beams does not have much effect on their hysteretic behavior, and add their energy absorption capacity only around 10 percent.