Seismic performance evaluation of steel arch bridges against major earthquakes. Part 2: Simplified verification procedure

摘要

The performance-based philosophy has been accepted as a more reasonable design concept for engineering structures. For this purpose, capacity evaluation and demand prediction procedures for civil engineering structures under earthquake excitations are of great significance. This work presents a displacement-based seismic performance verification procedure including capacity and seismic demand predictions for steel arch bridges and investigates its applicability. Pushover analyses is employed as a basis in this method to investigate the structure's behaviors. A failure criterion for steel members accounting for the effect of local buckling is involved and an equivalent single-degree-of-freedom (ES-DOF) system with a simplified bilinear hysteretic model formulated using pushover analyses results is introduced to estimate the displacement capacity and maximum demand of steel arch bridges under major earthquakes. To check the accuracy of the proposed method, seismic capacities and demands from multi-degree-of-freedom (MDOF) time-history analyses with Level-Ⅱ design earthquake record inputs modeling major earthquakes are used as benchmarks for comparison. By a case study, it is clarified that the proposed prediction procedure can give accurate estimations of displacement capacities and demands of the steel arch bridge in the transverse direction, while insufficient for the longitudinal direction, which confirms the conclusion drawn in other structure types about the applicability of pushover analyses.