Health Monitoring And Condition Assessment Of Long-span Concrete Cable-stayed Bridge

Nowadays, it is very important to assess the safety of cable-stayed bridges at its maintenance stage, through the evaluation of its stability as a whole, the rigidness of the main beam and main tower, and the cable force. The research investigates the Qing River bridge of the Hu Rong Xi highway, which is located in Hubei province. Based on the in-situ measurement data collected at the preliminary construction control stage, the health stage of the Qing River bridge in its operation period has been assessed, which includes:(1) A dynamic finite element program for cable force measurement has been made, to analyze the variation of the cable force with respect to the change in construction stage and constraint. A formula for the installation location of the thimble vibration damper with respect to frequency change percentage was proposed, in order to predict the frequency change range of the cable, the effectiveness of which has been verified by real examples. The available practical formulas for calculating cable force has been compared, in terms of the error when they are applied to compute the cable force by using frequency method. Verified by real examples, the best practical formula was proposed for application.(2) The finite element model for health monitoring has been built, and the real stress condition of the bridge was to correct the model. Based on the model, the theoretical shrinkage of the bridge was computed according to different codes. This and the influence of reinforcement in the model on the measurement items were both considered, to provide some reference for the condition assessment of the bridge.(3)Proposed a direct support to consider the stiffness of the cable between the cable force calculation method, so the actual project, in the absence of support by the test equipment before and after the middle of the frequency change, you can not get cable force conversion factor the circumstances, still it can get Accurate cable force value.(4) The measurement of the cable force, strain, deformation, and the dynamic effect of the bridge at the initial stage and at the stage after operating for one year was compared. The shrinkage code, whose prediction is more consistent with the measurement data in reference to the theoretical calculated value based on the built finite element model, was chosen to assess the health condition of the Qing River bridge after operating for one year, and predict the future trend of the measurement aspects.