Applicability of pushover analysis-based seismic performance evaluation procedure for steel arch bridges

An investigation on the application of a capacity and demand prediction procedure based on a nonlinear pushover analysis and an equivalent single-degree-of-freedom (ESDOF) system approximation for seismic performance evaluation of steel arch bridges, as well as limitations of the pushover analysis is presented here. The procedure is applied to the transverse direction of two representative arch bridges with different spans for capacity and demand estimation. Displacement capacities are obtained by conducting pushover analysis until the ultimate state of the structure is reached, determined by a failure criterion proposed for thin-walled steel members governed by the local buckling-induced failure. Displacement demands under major earthquakes are estimated by ESDOF systems formulated using pushover analysis results. Capacities and demands are then compared with those from rigorous nonlinear time–history analyses on multi-degree-of-freedom (MDOF) models for verification and acceptable accuracy of the pushover analysis-based procedure is evidenced. Furthermore, applicability of the pushover analysis involving the fundamental mode only for seismic performance evaluation is extensively investigated considering the higher mode effect. A factor to account for higher mode contribution to seismic response is proposed and an applicable range of using the pushover analysis is quantitatively specified.