Abstract
In order to solve the problem of vehicle-bridge coupling vibration of a continuous semisteel bridge, the main bridge type of long-span prestressed concrete girder bridge, the author proposes a bridge safety test system based on the dynamic and static load test. The system combines the change of stress and deflection with the vibration amplitude of the bridge body, and using the modeling assistant in large-scale finite element software MIDAS/CIVIL, a three-dimensional finite element real bridge model is established, including input of section data, the input of boundary conditions, and the input of loads. The result obtained is as follows: the structural verification coefficient of the control strain of the main girder under each working condition is not greater than 1.0, indicating that the flexural rigidity of the structure meets the design requirements. In addition, under each working condition, the ratio of the residual strain after unloading to the measured total strain is less than 20%. Under each working condition, the deflection calibration coefficient of each control section is less than 1.0, and the ratio of residual deflection to total deflection of each measuring point is at most 3.9%; each residual deflection is small. The damping ratios are all less than 5% of the empirical damping ratio of concrete members, indicating that the bridge structure is in good condition. The result obtained by the author is compared with the standard allowable value and the theoretical calculation value, so as to provide a basis for the study of the bearing capacity of similar bridges and to verify the standardization and rationality of the existing bridge structural design.