Design of seismic strengthening technique for soft-story rc frames using buckling-restrained braces

This study is focused on the seismic strengthening of reinforced concrete (RC) frames with soft-stories using buckling-restrained braces (BRBs) in order to control the severe damages or complete collapse of these frames. A design procedure has been proposed to determine the BRB sizes required for the target design base shear of the study frames. The seismic performance of the strengthened frames is evaluated numerically using a computer software SAP2000. The modelling technique adopted for BRBs and frame members are discussed. Linear modal analyses are carried out to determine the mode shapes and time periods of the strengthened frames. Nonlinear static and dynamic analyses are carried out to investigate the lateral strength, failure mechanism, interstory drift response and residual drift response of the study frames. The seismic performance of the strengthened frames is also compared with those of the unstrengthened frames. The installation of BRBs significantly improved seismic performance of 4-story and 8-story RC frames with soft story. However, the lateral load-resisting potential of BRBs could not be fully utilized in the 20-story RC frame with soft ground story. © 2019, Associated Cement Companies Ltd. All rights reserved.