Assessment of Postearthquake Losses in a Network of Aging Bridges

Abstract

The current study approaches the issue of deteriorating civil infrastructure components in a systematic manner through microscale, mesoscale, and macroscale investigations. At the microscale, the integrity of individual network components is examined considering the extent of deterioration due to aggressive environmental conditions and climatic effects. For this purpose, the deterioration of structural members is evaluated through a detailed finite-element framework and the corresponding structural models are updated at regular time intervals to capture the effects of aging mechanisms. To quantify the vulnerability of deteriorating components subjected to earthquake events, a series of nonlinear time-history analyses are performed and time-dependent seismic fragility curves are generated. Based on the state of damage in the network components under a set of scenario earthquakes, appropriate damage indexes are introduced to measure the postevent functionality of the network at the mesoscale. Through the study of a full-scale transportation network that serves a large metropolitan area, an integrated traffic assignment model is then developed to estimate the travel time in the network before and after an earthquake event. At the macroscale, the analyses go above and beyond the components of the transportation network and provide a holistic approach to calculate the losses associated with disruptions in deteriorating networks due to extreme events.