Rehabilitation of reinforced concrete structural walls using fibre composites

Reinforced concrete structural walls are an effective system for resisting lateral loads. Under earthquake loading, flexural walls are expected to exhibit a ductile behaviour and dissipate energy through the formation of a flexural plastic hinge near the bottom part of the wall. Premature shear failure of structural walls designed according to pre-seismic building codes was observed in several recent earthquakes.; An experimental program for investigating potential rehabilitation schemes to increase the shear strength and ductility of the walls is undertaken. An innovative test setup that provides the possibility of controlling the ratio of the shear force to both bending moment and axial load is used. A control wall designed according to pre-seismic building codes was tested and exhibited non-ductile shear failure mechanism. Two different rehabilitation schemes using fibre reinforced polymers (FRP) and through anchors were designed to improve the strength and ductility of the wall. Results showed the implemented rehabilitation schemes were successful in preventing the shear failure and enhancing the ductility of the walls.; Nonlinear finite element analysis was performed for the test walls using special eight-node solid concrete elements, nonlinear steel strut elements, and layered eight-node FRP solid elements. The predicted failure loads and the stress and strains distributions agreed with the experimental results. Another analytical model for the specimens based on the compression field theory was presented. A material model for reinforced concrete walls confined using FRP was developed. The analytical model was used for push-over analysis for wall specimens rehabilitated using FRP that are available in literature as well as the ones tested in this program. The model was successful in the prediction of the displacement, ultimate load, and mode of failure. A parametric study was performed to evaluate the effect of different parameters on the effectiveness of the rehabilitation scheme and provide guidelines for the design of the proposed rehabilitation schemes.