About the author:

1. College of Architecture and Civil Engineering, Kunming University, Kunming, Yunnan 650214, China;2. Yunling Construction Co., Ltd. of Yunnan Communications Investment & Construction Group, Kunming,Yunnan 650032, China; 3. Yunnan Tongqu Engineering Testing Co., Ltd., Kunming, Yunnan 650041, China

Abstract:

In order to accurately evaluate the bearing performance of a PC continuous box girder bridgeon a certain expressway after a fire accident, on the basis of routine testing, on⁃site load tests wereconducted and suggestions for repair and treatment measures were proposed. Before the test, the finiteelement method was used to analyze the stress and deformation behavior of the bridge in its design andusage state. During test, the strain and deflection of the control section of the bridge span structureaffected by fire were tested, as well as the natural frequency, damping ratio, and impact coefficient of thebridge. The test results showed that after this fire accident, the working conditions of the strain anddeflection deformation of the box girder could still meet the design requirements. The overall stiffness ofthe bridge did not show significant degradation, and there were no obvious abnormal defects ordeterioration in the upper structure and support system. The impact effect generated by normal drivingvehicles still met the design requirements. The bearing capacity and dynamic performance of the bridgecould still meet the design and usage requirements. In order to ensure the operation safety and drivingcomfort during the recovery of traffic after repair, it is recommended to take speed limit measures tocontrol the vehicle speed within 60km / h. Load tests can be used to conduct a more effective assessmentof the bearing performance of bridges after a fire, so as to improve the scientific nature of repair andtreatment measures.