Development of fragility curves and evaluation of limit state values of seismic performance of optimal reinforced concrete bridge with semi-isolated deck

In the previous study, optimization based on genetic algorithms on the design specifications of isolators and reinforced concrete piers of a famous multi-span highway bridge was performed, and an optimized bridge with a semi-isolated deck was proposed. In this study, using incremental dynamic analysis, by selecting two cases of displacement of the semi-isolated deck and displacement of the isolators or the shear strain of the isolators, the incremental dynamic analysis curves are obtained under the records proposed in FEMA P695. Then, while performing fragility analysis based on the results of incremental dynamic analysis, fragility curves are determined for the displacement of the semi-isolated deck and the displacement of isolators or the shear strain of the isolators in longitudinal and transverse directions of the bridge. Based on these curves, the values of the limit states for structural collapse, life safety, moderate damage, slight damage and first yield has been identified and proposed.