Major seismic events during the past few decades have continued to demonstrate the destructive power of earthquakes, with failures to buildings, bridges, industrial and port facilities, as well as giving rise to great economic losses. However, in low to moderate seismicity regions, seismic resistant design is still considered complicated and expensive in terms of actual seismic risk. This is partly due to the fact that design codes do not have any special consideration for these regions; also, economic factors have not been integrated fully with the design principles.
Bridges are the most critical components of the transportation network, as failure of bridges can disrupt the total transportation system, and hence deserve proper consideration in terms of seismic risk. A systematic approach is proposed for evaluating the cost-effectiveness of existing bridge 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. It is demonstrated that life cycle cost should be considered in the design phase of a new/retrofitted structure, and the target performance significantly depends on the expected average daily traffic.