Experimental Verification of Spliced Buckling Restrained Braces

A critical facility constructed in the 1980s was housed in a building whose original seismic force-resisting system included chevron-braced frames and pre-Northridge earthquake moment frames. In the mid-1990s, a code-based seismic retrofit was designed. This phased retrofit was only partially completed. A more recent seismic evaluation of the building in its partially retrofitted condition revealed major structural deficiencies. Another retrofit was designed using field-spliced buckling restrained braces (BRBs) that allowed the building to remain operational during construction. The paper summarizes the analyses performed for the seismic retrofit and the development, prototype testing and erection of the spliced BRBs. The project testing protocol was compared with current AISC Seismic Provisions' testing protocol for BRBs (AISC 341-10), which shows that if properly detailed and fabricated, BRBs used for this retrofit project can have peak and cumulative ductility well in excess of the current AISC testing criteria.