A PRACTICAL DESIGN METHOD OF REINFORCED CONCRETE FRAMES RETROFITTED WITH BUCKLING-RESTRAINED BRACES

Buckling-restrained braces (BRBs) can significantly decrease the interstory drift demand of reinforced concrete (RC) frames under earthquakes. A practical design method of RC frames retrofitted with BRBs is proposed to avoid local strengthening of deficient structural members one by one, whose seismic details do not satisfy the current code. The weakest bearing capacity column and weakest plastic hinge concepts are adopted to solve the bearing capacity problem of structural members and the interstory drift problem of frame systems, respectively. A specific design procedure of the proposed design method is presented. Seismic retrofit design of a seismically-weak library reading building is conducted and the effectiveness of the proposed design method is verified. It shows that both the bearing capacity and interstory drift of the retrofitted frame satisfy the requirement of the current seismic code. The results of the present study are expected to be useful for the preliminary design of RC frames retrofitted with BRBs.