Risk-Based Proof-Load Requirements for Bridge Evaluation

Abstract

Proof-load testing is considered a reliable approach to evaluation of an existing structure's load-carrying capacity. It can be effectively used for highway bridge evaluation, to either enhance an existing rating obtained by an analytical method or establish a rating for bridges unsuitable for analytical rating. Proof-load factors in design and evaluation codes vary, and their basis has not been well documented. For highway bridge evaluation in the United States this paper proposes proof-load requirements in the format of load and resistance factors, to determine target proof loads and resulting load ratings. They are derived to reach target structural reliability levels consistent with current practice by analytical methods, and to ensure relatively uniform safety of bridges. These requirements may be included in specifications for highway bridge evaluation by proof-load testing in the United States, and their application requires little knowledge of structural reliability theory.