Fe Model Updating And Bearing Capacity Evaluation Of Prestressed Concrete Hollow Slab Bridge

In the construction of road and hydraulic engineering project in our country, bridges that have different styles and spans have been built on a large scale. However, bridges will gradually aging and lose their bearing capacity with the coefficient effect of climate, environment and external load in the process of service. Nevertheless, the traffic flow and the vehicle weight are gradually increasing along with the economic and social development. Therefore, we must carry on the scientific evaluation of the bearing capacity of existing bridges in order to grasp its true working state and carrying potential. It will offer the decision basis for renovation and use management.In this paper, a comprehensive bearing capacity evaluation method which based on dynamic finite element model updating is used to check the safety and analyze the bearing capacity of an existing prestressed concrete simply supported hollow slab bridge. The application result shows that using this method can achieve more comprehensive, nondestructive and inexpensive bearing capacity assessment, and provide a reference for similar bridge assessment in future. The main work of this paper are as follows:(1) Establish a detailed finite element model of bridge according to the design drawing, and calculate the frequency and modal shape parameters. Then analyse the influence of prestress and bearing stiffness on modal calculation results of finite element method.(2) Introduce the the basic method of bridge dynamic testing and modal parameter identification. Then use the subsequent effect of moving vehicles and the peak power spectrum method to incentive and test the bridge, identify its experimental modal frequency and vibration model. At last, analyze and compare the field testing results with the computational results of initial finite element model analysis.(3) Conduct sensitivity analysis to the primary parameters in finite element model, and select the high sensitivity structural modal parameters as the model correction parameters. Then modify the finite element model according to the objective function which joint frequency and MAC values, to get a new modal which can better reflect the real working state of the structure.(4) Calculate load responses of the bridge under design load with the modified finite element model. Then evaluate the bearing capacity comprehensively combining with data of appearance investigation, material condition, natural vibration frequency and dynamic performance. At last, analyse the effect on bearing capacity under ultra design standard load and insufficient prestressed tension.