PERFORMANCE-BASED SEISMIC RETROFIT DESIGN FOR RC FRAMES USING FRP COMPOSITE MATERIALS

Seismic retrofitting of reinforced concrete (RC) members using fiber reinforced polymer (FRP) composite materials has become a well-established technique for repairing and strengthening seismically deficient systems. Although there has been significant progress on behavioral modeling of FRP retrofitted RC members as well as on implementation of performance-based analysis and design concepts, the studies investigating the overall seismic behavior of the retrofitted frames are still limited. This paper presents a methodology for performance-based FRP retrofit design for RC frames and provides an analytical investigation of this through numerical studies performed on 2-D frame models with different retrofit configurations. More specifically, frame systems with square or rectangular columns were assumed to be retrofitted through FRP strengthening of beams for improved flexural capacity and/or wrapping of columns for additional confinement and resulting ductility. Nonlinear pushover analyses of frames before and after retrofitting were performed using nonlinear hinge parameters determined from moment-curvature analyses based on comparative use of various steel- and FRP-confined concrete models proposed in the literature. Analysis results reveal the expected contribution of each retrofit configuration to the seismic behavior and performance of the frames, highlighting various design considerations for proper FRP retrofit decisions.