Non-linear finite element analysis and parametric investigation of low-rise reinforced concrete shear walls.

Abstract

A parametric study was carried out on 18 reinforced concrete shear walls to investigate the significance of design parameters on seismic response. The parameters included boundary elements and their reinforcement characteristics, web reinforcement ratios, concrete strength, steel yield strength, and axial load. The investigation was conducted using finite element analyses. Computer program ADINA was used to perform nonlinear analysis of concrete shear walls under axial load and incrementally increasing lateral forces. Material nonlinearities, including those of concrete, were modeled using ADINA material models. Four-node isoparametric plane stress elements were used to model concrete. Steel elements were modeled using two-node nonlinear truss elements. The applicability of the program and the accuracy of finite element models were first validated. This was done by comparing the results of six different shear walls with those obtained experimentally. The walls included three specimens tested by Maier at the Swiss Federal Institute of Technology in Zurich, Switzerland and three shear walls tested by Lefas et al. at Imperial College of Science and Technology, London, England. The analytical and experimental results showed very good agreement. The results of the parametric investigation indicate that the presence of boundary elements enhanced strength and deformability of shear walls significantly. Wall aspect ratio was also found to be an important parameter dictating the mode of behavior. The longitudinal reinforcement ratio in the boundary elements was found to be a good source of energy dissipation and had much greater influence on ultimate load capacity than the web reinforcement. When confinement of concrete was considered, both the ultimate load capacity and ductility of shear walls improved. The effects of increased axial compression and increased reinforcement yield level were to increase strength but reduce ductility.