Redundancy and Operational Safety of Composite Stringer Bridges with Deteriorated Girders

摘要

As a critical component of the national transportation network, bridges have received a lot of attention regarding their safety and condition state. Bridge superstructures begin to degrade after they are placed in service; to combat this issue, owners have begun to utilize a variety of technologies to monitor the behavior and detect different sources of damage in these structures and generate higher fidelity condition metrics. However, an appropriate maintenance decision-making process requires knowledge of the influence of detected damage and deterioration mechanisms on the overall system behavior. This paper presents a performance measurement and evaluation framework that can be used to characterize the impact of deteriorating conditions on the performance of in-service bridge superstructures. The framework was established based on a numerical modeling approach and was validated through a sensitivity analysis of two representative in-service composite steel girder bridges under the impact of corrosion in the girders, with an objective of evaluating the impact on functionality and operational safety. The sensitivity analysis utilized a series of nonlinear finite-element analyses to assess the system-level structural performance under a variety of damage scenarios. Results from the analyses demonstrated that the shape of the damage configuration has negligible effect on the capacity reduction in deteriorated structures, while the damage depth can significantly reduce the capacity of the structure (up to 60%). It is expected that the proposed framework for evaluating system behavior will provide a first step for establishing a critical linkage between design, maintenance, and rehabilitation of highway bridges, which are uncoupled in current infrastructure decision-making processes.