Damage Detection and Decreased Load-Carrying Capacity Assessment of a Vertical-Lift Steel Truss Bridge

Abstract

Over a bridge’s service life, physical damage, such as material deterioration, accidental impact, and overloading, can decrease its load-carrying capacity. To assess the integrity and serviceability of in-service bridges, accurate and efficient structural health monitoring is required for as frequent intervals as feasible. In this study, an integrated decision-making protocol is proposed to continuously postprocess collected dynamic-response data of a bridge to notify the bridge owners of any noticeable change in the in-service condition of the structure, at system level, and to more fully understand the in situ performance of the bridge for triggering smart inspection techniques (e.g., visual inspection, modal identification methods). This is done to determine the location and severity of damage and calculate the bridge load-carrying capacity based on the given damaged component(s). The study for this protocol is an instrumented vertical-lift truss bridge subjected to four simulated damage scenarios. For both the healthy and simulated damage conditions, a verified structural model is used as a baseline to determine the structural system response for damage detection using a wavelet-based energy rate index and to investigate the bridge load-carrying capacity according to current standards for load resistance factor-rating approach due to likely damage scenarios.