Performance Assessment of Deteriorating Bridge Channels in the Presence of Hurricane Failures: The Competing Risks Scenario

Abstract

Natural disasters such as hurricanes, earthquakes, and storm surges among other hazards affect communities and large geographic areas of the United States, resulting in negative repercussions on civil infrastructure. The impacts of these hazards on bridges affect the operability and functional integrity of transportation networks. This study focuses on two failure modes, namely the deterioration of bridge channels in the presence of competing hurricane hazards (hurricane-induced failure of channels) and the complex interactions between the two modes of failure, to evaluate the performance of bridge channels. To achieve the aforementioned objective, competing risks models are developed for the already-mentioned failure modes using the product limit survival analysis, cause-specific hazard rates, and the cumulative incidence functions (CIF). Failure time distributions are developed for standard commonly recognized bridge channel elements using legacy inspection data for bridges, annual probabilities of occurrence of hurricanes, and damage matrices from existing hurricane records. The method of maximum likelihood estimation (MLE), weighting techniques, and inference procedures are employed to describe competing risks event data for the analysis. From the results, it is observed that bridge channels deteriorate faster in the urban areas compared with rural areas. The deterioration and hurricane failures generally yield significantly different impacts based on the log-rank chi-square outputs. Also, it was observed that the impact of hurricane Categories 3 and 2 on bridge channels were more significant (based on the hazard ratios) at the coast than noncoastal areas and also generally high for urban bridge channels compared with rural channels.