Life-cycle resilience of deteriorating bridge networks under earthquake scenarios

Resilience of bridges and infrastructure networks is generally investigated considering damage and disruption caused by sudden extreme events, such as earthquakes. However, damage could also arise continuously in time due to aging and structural deterioration, which can modify over time the structural performance and functionality and, consequently, the system resilience. Therefore, for critical infrastructures exposed to seismic and environmental hazards, resilience depends on the time of occurrence of the seismic event. This paper investigates the life-cycle seismic resilience of aging infrastructures and presents a probabilistic approach to seismic assessment of deteriorating bridges and resilience analysis of road networks under prescribed earthquake scenarios. The time-variant seismic fragilities of the deteriorating bridges in the network are assessed for several limit states, from damage limitation up to collapse. The seismic demand is evaluated for each bridge based on a ground motion prediction equation in terms of earthquake magnitude and epicentral distance. The corresponding levels of seismic damage are derived from the time-variant fragilities and related to vehicle restrictions and traffic limitations. A traffic analysis is carried out over the entire road network to compute both the time-variant system functionality and life-cycle seismic resilience under prescribed post-event recovery processes. The proposed approach is applied to reinforced concrete bridges in a highway network with detour and re-entry link. The bridges are exposed to chloride-induced corrosion and earthquake scenarios considering different magnitude and epicenter location. The results show the detrimental effects of aging and structural deterioration and emphasize the role of the earthquake scenario on the time-variant seismic performance of bridge structures and life-cycle resilience of road networks.