Collapse limit state assessment of lightly reinforced concrete columns

A range of lightly-reinforced, poorly-confined RC columns were assessed for seismic safety based on the limit state of collapse in projected earthquake scenarios representative of the average level of seismicity in Australia. The hysteresis model for each of the columns analysed were first calibrated against results from cyclic tests and push over analyses up to the limit of gravity collapse. Inelastic time history analyses employing 40 spectrum compatible accelerograms on class C sites (AS 1170.4) were then conducted on the calibrated models. Fragility curves have also been constructed in accordance with results from incremental dynamic analyses. Results presented provide the basis for realistic seismic collapse assessment of the poorly confined reinforced concrete columns. Importantly, the size effects phenomenon has been revealed in this study.