EFFECT OF GROUND MOTION DURATION ON SEISMIC FRAGILITY OF RC FRAMES WITH DIFFERENT BEAM-COLUMN JOINT FAILURE MODES

Ground motion duration has great influence on the cumulative fragility and damage of inelastic structures, but the consideration of duration is not clear in current seismic analysis and design. 60 ground motion records with different durations and peak ground accelerations were selected from the PEER strong ground motion database, and categorized as 30 long-and 30 short-duration records. A three-dimensional model of an infilled RC frame teaching building was built via OpenSees. In order to simulate the different failure modes of the beam-column joints, three models were taken, which are the beam-column joints without considering inelastic deformation, with considering the bar bond-slip, and with considering both the bar bond-slip and the shear deformation. Seismic fragility analysis was carried out on the three models under the 60 ground motion records, and the fragility curves for two the kinds of records under different cases were obtained corresponding to five damage levels. Furthermore, the influence of ground motion duration on structural seismic behavior considering the different failure modes of beam-column joints was evaluated. The analytical results show that comparing with the short-duration records, the long-duration records can increase the structural exceedance probability obviously for the corresponding damage levels and beam-column joint cases. Comparing with the case without considering inelastic deformation of beam-column joints, both long-and short-duration records can increase the structural exceedance probability clearly under the same damage level when considering the bar bond-slip or considering both the bar bond-slip and the shear deformation. The effect of long-duration ground motion records on structural seismic performance considering the bar bond-slip and the shear deformation of the beam-column joints is more obvious.