Study on the vehicular load effect and the influence of top plate longitudinal cracks on box girder chamber based on static load test

In this study, an existing bridge, more than 20 years old and scheduled for demolition, was selected as the research subject to investigate the causes of longitudinal cracking in the top plate of box girders, as well as its impact on the mechanical properties of the box chamber frames. Static load tests were conducted on the entire bridge and the dismantled box girder segments. Additionally, numerical simulations were performed to analyze the effects of vehicular loads and the influence of cracks. The following results were revealed. First, the cracking load of the top plate in the test box girder segments was much larger than the axle weight of overloaded vehicles encountered in past years. Therefore, the single loading effect of vehicular load was not the primary external factor contributing to the formation of longitudinal cracks in the top plate. Second, the force transmission between the box girder's top and bottom plates, as well as the web plate, was normal during testing. Furthermore, longitudinal cracks only affected a small, localized area of the top plate's stresses and did not exert a significant impact on the mechanical properties of the box chamber frames.