The Seismic response of old deficient shear wall structures built in the 1960’s and 1970’s is investigated. The wall specimens investigated contain poor confinement, insufficient shear reinforcement, and lap splices of the longitudinal reinforcement located at the plastic hinge region. As a result of these deficiencies, the wall specimens have non-ductile response behaviour and require retrofit to enhance their seismic performance. Nine shear wall specimens with aspect ratio ranging from 0.65 to 1.20 subjected to quasi-static reverse cyclic loading are investigated as part of a comprehensive
research program. Analytical simulations utilizing the finite element method are conducted to predict the response of the wall specimens. Analytical results show that the models can accurately predict the elastic and inelastic behaviour and the failure mechanisms of shear walls strengthened and repaired with FRP sheets. The FRP material is effective in eliminating the brittle shear failure mode in walls with insufficient shear reinforcement.