Seismic Retrofitting of Existing RC Frames with Buckling Restrained Braces

This paper illustrates the results of experimental tests and numerical simulations carried out on full scale reinforced concrete (RC) existing frames retrofitted with buckling restrained braces (BRBs). Experimental tests were performed on two sample full scale RC building structures designed for gravity loads only. Such frames were subjected to cyclic pushovers to investigate their structural performance under earthquake ground motions. The results of the experimental tests show the efficiency of using BRBs to retrofit RC frames designed for gravity loads only. Such results were also confirmed by comprehensive non linear static and response history analyses carried out on an existing RC school framed building designed for gravity loads only and retrofitted with BRBs similar to those adopted for the tested full-scale frame. In such sample building the BRBs are placed along the perimeter of the existing frames to minimize the interruption of the functionality of the school and for easy of maintenance in the aftermath of major earthquake ground motions. The seismic performance assessment of the retrofitted structural system is illustrated in a detailed manner. Local and global response quantities are presented. The cost-effectiveness of the adopted retrofitting scheme is emphasised and further needs for the application of BRBs are highlighted.