Load-carrying capacity evaluation of girder bridge using moving vehicle

Abstract

Efficient and reliable load-carrying capacity evaluation of deficient bridges is essential for bridge maintenance and management. Based on load-carrying capacity evaluation of an existing bridge, operator can formulate strategies and implement countermeasures such as repair, strengthening or traffic regulation. Currently, static load test is used widely for evaluation of bridge load-carrying capacity. The test, however, is often considered expensive and requires massive traffic closure that hinders frequent implementation on highway or bridges in the rural area. In this paper, an efficient method for load-carrying capacity evaluation of girder bridges based on displacement under moving vehicle is proposed. The method consists of three main procedures, namely, radar-based dynamic displacement measurement under truck pass-by test, influence line extraction, and estimation of the displacement under the static load test scenario. Based on these procedures, evaluation of load-carrying capacity is conducted following the AASHTO manual. The method was verified in numerical simulations using three-dimensional finite element model of typical girder bridge under vehicle loading. Effects of vehicle weight, vehicle speed, and road roughness on the accuracy of displacement estimation were investigated in the numerical simulations. Full-scale implementation of the method was conducted on a simply supported prestressed concrete girder bridge to investigate feasibility of the proposed method and to provide guidance for practical application. The results reveal that load rating factor of the girders can be reliably evaluated. The evaluation process was also more effective and economical than the conventional method.