Bridge Seismic Retrofit Program Planning to Maximize Postearthquake Transportation Network Capacity

The bridge network, as part of the critical civil infrastructure, is susceptible to natural and man-made hazards. It is essential that the network retains its traffic-carrying capacity after a disastrous earthquake to ensure efficient evacuation of at-risk population to safe zones and timely dispatch of emergency response resources to the impacted area. Because of limited resources, it is important to prioritize bridge retrofit projects and manage disaster mitigation resources under a strategic budget plan. This paper proposes a methodology to find the optimal bridge retrofit program that aims to maximize the postdisaster network evacuation capacity. The uncertainties of earthquake intensity, bridge structural damage, and bridge traffic-carrying capacities are addressed by using a Monte Carlo simulation framework with established bridge fragility curves and damage-functionality relationships, and the effectiveness of preserving evacuation capacity is calculated on the basis of a network design model. The proposed methodological framework is demonstrated with the transportation network in Memphis, Tennessee, and numerical experiments show that the proposed framework solves the problem efficiently. The modeling framework can help transportation agencies maximize the effectiveness of investment. Emergency managers can also use the model to enhance preparedness and emergency response efficiency, which in turn improves the infrastructure systems' resilience against extreme events. DOI: 10.1061/(ASCE)IS.1943-555X.0000082. (C) 2012 American Society of Civil Engineers.