Optimal performance for cost effective seismic design of bridges

A systematic approach is proposed for evaluating the cost-effectiveness of existing design codes from the perspective of lifecycle cost consideration. In the life cycle cost formulation, cost of construction, damage cost, road user cost, as well as discount cost over the design life of the bridge are considered. The optimal performance is selected on the basis of minimum life cycle cost. The performance of a typical two-span bridge designed according to a current code provision for different earthquake ground motion levels is predicted and optimal target performance is selected based on life cycle cost with different assumptions of user cost. It is demonstrated that life cycle cost should be considered in the design phase of a new structure or of a structure to be retrofitted, and the target performance significantly depends on the expected average daily traffic for the road.