Analytical study on seismic retrofitting of reinforced concrete buildings using steel braces with shear link

This paper is focused on a proposed seismic retrofitting system (PRS) configured to upgrade the performance of seismically vulnerable reinforced concrete (RC) buildings. The PRS is composed of a rectangular steel housing frame with chevron braces and a yielding shear link connected between the braces and the frame. The retrofitting system is installed within the bays of an RC building frame to enhance the stiffness, strength and ductility of the structure. The PRS and a conventional retrofitting system using squat infill shear panels (SISPs) are used in an existing school and an office building. Nonlinear time history analyses of the buildings in the original and retrofitted conditions are conducted for three different seismic performance levels (PLs) to assess the efficiency of the PRS. The analyses results revealed that the building retrofitted with the PRS has a more stable lateral force–deformation behavior with enhanced energy dissipation capability than that of the one retrofitted with SISPs. For immediate occupancy PL, the maximum inter-storey drift of the building retrofitted with the PRS is comparable to that of the one retrofitted with SISPs. But for life safety and collapse prevention PLs, the maximum inter-storey drift of the building retrofitted with the PRS is considerably smaller than that of the one retrofitted with SISPs. Furthermore, compared with the building retrofitted with SISPs, the building retrofitted with the PRS experiences significantly less damage due to the more ductile behavior of the system at the life safety and collapse prevention PLs.