Performance Assessment of the Roll-N-Cage (RNC) Isolators impacts on Progressive Collapse Behavior in Cable-Stayed Bridges

Structural safety can be threatened by failure of one member of the structure if it results the failure of other members of the structure. This phenomenon, which has recently attracted the attention of designers and engineers, is known progressive collapse. Progressive collapse, especially during a severe earthquakes, could threaten the general stability of structures and lead to their collapse. In this research, it has been aimed to investigate the performance of the isolated cable stayed bridges with modern Rolled-N-Cage (RNC) isolators under near-fault seismic loads and after losing a cable. In this regard, Bill Emerson isolated Cable-Stayed Bridge is implemented under three near-fault seismic events and assessed the results of the cable loss. Then, buffer mechanism of RNC isolator and its effects against preventing progressive collapse is evaluated on preventing progressive collapse of the bridge. The results indicate that the RNC isolator with activated buffer mechanism appropriately decreases the permanent displacement under near-fault seismic loads. While, not using of the RNC isolator and buffer mechanism, causes the damage propagation and progressive collapse of the bridge.