Seismic performance assessment of urban transportation networks: A unified approach to link damage and performance metrics

Transportation networks are essential for the economic growth and functionality of societies. Their seismic performance is pivotal for assuring post-hazard resilience. However, its evaluation remains challenging due to the cumulative effect of component damage on the functionality of links with multiple bridges. Moreover, existing metrics often fail to provide an accurate and normalized representation of network performance across various disruption levels. Therefore, this study presented a novel approach, the Feasible Combinations Method (FCM) for link damage evaluation. Weighted-random distributions of bridge damage states and their feasible combinations were used to evaluate the probability of link damage states via Monte Carlo simulations. Furthermore, a new normalized performance metric, the Travel Cost Weighted Satisfied Demand (TCWSD) was introduced, which integrated satisfied travel demand with nonlinear changes in travel time during seismic events. The findings showed that FCM offered significant computational efficiency over the existing method with a maximum error of 0.3 %. The TCWSD consistently evaluated the network performance, mitigated the shortcomings of existing metrics, and showed very strong correlation of 93 % with network damage for three transportation networks. This study offers a practical tool for assessing network functionality, prioritizing retrofitting, optimizing disaster responses, and enhancing network resilience.