Finite element analysis of effect of concrete confinement on behavior of shear walls

When concrete in the compression zone of a shear wall is confined by transverse reinforcement, both the strength and ductility of the wall would be increased. However, none of the existing analysis methods in the codes allows for such effect. Herein, a finite element model that takes into account the effect of concrete confinement is developed for nonlinear analysis of reinforced concrete structures. In this model, the confinement effect of the transverse reinforcement is incorporated by adjusting the compressive stress–strain relation of the concrete according to the confinement index proposed by Kappos. Shear wall models tested by others under constant vertical load and monotonically increasing horizontal load are analyzed and the analytical results for the failure modes and load–deflection curves of the walls are found to be in good agreement with the experimental results. Using the finite element model, a parametric study on the contribution of concrete confinement to the lateral resistance of shear walls is conducted. It is revealed that the effect of concrete confinement is more significant in walls with greater height to width ratio and/or subjected to larger axial compression load.