Seismic Retrofitting of Typical Illinois Bridges by Response Modification

The impact of seismic retrofitting of typical Illinois bridges, via response modification using friction pendulum bearings (FPB), on the state economy is studied. For this purpose, two typical bridges with distinct characteristics were selected by Illinois Department of Transportation (IDOT). The seismic analyses of the bridges revealed that the bearings, wingwalls and substructures are vulnerable and need to be retrofitted. Conventional retrofitting strategies are developed for the bridges and the retrofitting costs are estimated. The same bridges are further studied to develop appropriate techniques for upgrading their seismic capacity using FPB and the seismic analyses are repeated. It is observed that the FPB effectively mitigated the seismic forces and eliminated the need for retrofitting of the substructures of the bridges. This resulted in a considerable reduction in the seismic retrofitting costs of the bridges.