Comparative study on the performance of different seismic isolation systems in highway bridges subjected to near-fault earthquakes

Bridges are vital arteries of the transportation network of every country, whose collapse during a strong earthquake discontinues their performance in circumstances that they are required to provide emergency services and facilitate the evacuation of a damaged region. The implementation of base isolation bearings is one of the effective methods in the developed countries to retrofit bridges. In this study, stress-strain response of base column from five different models of a highway bridge seismically isolated with: (1) Single Friction Pendulum, (2) Triple Friction Pendulum, (3) High Damping Rubber and (4) Lead-Rubber seismic isolation bearing plus (5) a typical bridge model by assuming a rigid connection between the deck and bridge piers is calculated. Responses were calculated by performing nonlinear time history analyses by considering the main aspects of the simulation and by taking into account the nonlinear behavioral complexity of the base isolation bearing in OpenSees software. Results indicated that the frictional base isolations significantly reduce the stresses induced in the columns of the seismically isolated bridge in comparison with the typical bridge model, and improved the seismic performance of the bridge substantially. The percentage of reduction for triple frictional pendulum bearings reached 89%.