Bridges, Tunnels and other Transportation Structures
Full Session with Abstracts
Fatigue cracks in steel bridges are considered a nuisance as they require periodic inspection and repair. Although the cracks are typically characterized by stable propagation rate, the scatter in fatigue performance is difficult to quantify and could be on the order of thousands or even millions of cycles. If left unattended, the cracks could grow to reach critical length and threaten the integrity of the structure. The concern over structural safety is further intensified for fracture critical bridges, resulting in a federal mandate of bi-annual hands-on inspection and causing financial strains on funding available to transportation departments. Given the scatter in fatigue data and the substantial cost associated with inspection and repair, the use of probabilistic life-cycle cost analysis could, therefore, provide a viable alternative for the development of maintenance and management programs for steel bridges. In this paper, a framework for probabilistic life-cycle assessment is created and applied for minimizing the life-cycle cost of a steel twin tub bridge. First, a detailed finite element model of the bridge is developed and probabilistic relationships of crack growth versus number of cycles are generated. Second, a life-cycle framework is devised and used to optimize the cost and schedule associated with repair and inspection of the bridge over its service life without comprising on safety. The results demonstrate that viability of using this framework for ensuring the lowest possible cost for addressing fatigue issues in steel bridges over a service life chosen by the bridge owner while ensuring safe operation of the bridge.