Seismic performance assessment of RC bridges with self-centering post-tensioned piers using fragility curves

Bridges play a key role in transportation networks, and damage to them during an earthquake may delay emergency rescues and first-aid efforts. Thus, the development of structures with low damage and reduced downtime after extreme earthquake events is necessary. Post-tensioned self-centering (SC) systems improve the serviceability of bridges by eliminating residual displacements after severe earthquakes. In these systems, post-tensioned tendons have a critical role in self-centering piers so that they return the structure to its initial position and remain their functionality. In this study, the seismic performance of post-tensioned rocking bridge piers was investigated and compared with monolithic reinforced piers through time history analysis. Demand and capacity of bridges in models with different heights were investigated using incremental dynamic analysis (IDA). The probability of failure of each bridge has been investigated by studying the fragility analyses based on the maximum drift ratio and the stress of the tendons. According to the results, the collapse probability of bridges with conventional piers is higher than their corresponding bridge models with SC piers. Adding dampers to the SC piers increases the lateral load capacity of the model and decreases the probability of failure under an earthquake record with specific peak ground acceleration (PGA). On the other hand, using dampers in SC piers improves the energy dissipation capacity of the system and reduces the possibility of tendon yield by reducing the maximum displacement.