Effect of strength and stiffness of buckling-restrained braces on seismic retrofitting of reinforced concrete buildings

This thesis presents an analytical study aimed at evaluating the effect of using buckling-restrained braces (BRBs) on the seismic retrofitting of 3 and 6 storey reinforced concrete (RC) buildings. In the design of the BRBs with non-prismatic cross-sections, twelve combinations of ? and ß design parameters that influence the strength and stiffness of the BRBs, respectively, were considered. The response of the RC structures with and without BRBs under earthquake ground accelerations were evaluated through nonlinear dynamic analysis. Two sets of ground motions representative of the design earthquake with 10% and 50% exceedance probability in fifty years were taken into account. By comparing the structural performance of the original and buckling restrained braced structures, it was observed that the use of the BRBs were very effective in mitigating the seismic response as a retrofit scheme. However, the selection of the strength and stiffness parameters of the BRBs had considerable effect on the response characteristics of RC structures such as by increasing the value of ? and by decreasing the value of ß of the buckling-restrained braces, the maximum deformation demand of the structures increased.