The Federal Highway Administration is turning to risk-based, data-driven ways of evaluating and rating bridges. Shay Burrows, team leader for structures safety and management for the FHWA, said that the agency is replacing traditional sufficiency rating numbers with simpler terms such as “good,” “fair,” and “poor” in describing bridges. Speaking to attendees of the International Bridge Conference last month, he noted the recently issued “Refined Analysis in Bridge Design and Evaluation” manual from the FHWA, which provides guidelines for engineers to use “refined” analysis in modeling bridges.
The manual states: “Current … Bridge Design Specifications feature a reliability-based approach to bridge design…and limit state design with conservatism built in to envelope the limits of applicability and consider all the relevant parameters. Conservatism always adds unnecessary cost, which may have serious implications for owner-agencies with limited budgets.” Moreover, the manual states that “designers …focus on developing and using complex automated calculation tools to execute the necessary code checks rather than performing meaningful structural modeling to better understand behavior and address the limit states that are being evaluated. This often hides the controlling factors and hinders the development of new bridge innovations in general. A properly and efficiently executed refined analysis can provide substantially better information about the state of stress in a bridge and allow for more cost-effective and reliable design.” [Read more…]
