Impact of Friction Pendulum Bearings on the Seismic Retrofitting Cost of Typical Bridges with Wall Type Piers in the State of Illinois

The economical efficiency of friction pendulum bearings (FPB) for seismic retrofitting of typical Illinois bridges with wall type piers is studied. A typical bridge with heavy wall piers was carefully selected by Illinois Department of Transportation (IDOT) for the purpose of this study. The seismic analysis of the bridge revealed that the bearings, and substructures of the bridge are vulnerable and need to be retrofitted. A conventional retrofitting strategy is developed for the bridge and the cost of retrofit is estimated. Next, the bridge is further studied to develop appropriate techniques for upgrading its seismic capacity using FPB and the seismic analysis is repeated. It is observed that the FPB effectively mitigated the seismic forces and eliminated the need for retrofitting of the substructures of the bridge.