Optimal design strategies for base-isolated bridges

Base isolation of bridges provides an excellent defense against the damaging effects of earthquakes. For this design strategy, flexible supports are placed between the deck and substructure. This changes the lowest periods of vibration of the bridge and shifts it to a period where little energy is present in the earthquake motions.The use of different combinations of isolation, recentering, and energy dissipating systems provides a very good opportunity to optimize the total structural design.A simplified method for the preliminary design of base isolated bridges is presented. This method takes into account the flexibility of the piers and soil-structure interaction which are shown to be important.The method of analysis, modeling assumptions and optimization procedures for isolated bridges are also described. The objective is to achieve the best seismic performance at the least cost. The study indicates that considerable cost of the foundations may be saved if base isolation is used.U of I OnlyETDs are only available to UIUC Users without author permissio