Moving Force Identification Of Bridge-vehicle System Based On FEM And Wavelet-Galerkin Method

The load environment of bridges is a very important factor for bridge maintenance and condition assessments。Many researchers have paid great attentions to the moving loads on the bridge. The bridge-vehicle system is modeled by two axles vehicle model and simple-supported beam(include prestressing force or not).Using Wavelet-Galerkin method for solving equation of motions, a new moving force identification method is developed in this thesis based on finite element method. The main idea makes use of Daubechies orthonormal bases to transform the differential equations into linear equations in wavelet space, and then solve the set of simultaneous equations to get the solution, transform the solution back into physical space to identify the moving loads or the prestressing force. Numerical simulations demonstrate the efficiency of the method using selected measurements. The influence such as the arranging of measurement sensors, wavelet's resolution (related to sampling frequency) is also discussed. Conclusions are:(1) There is critical resolution existing in moving force identification. When the resolution is lower, large local error arises, and when higher, good results will be present . little improvement presents with the augment of resolution.(2) The asymmetric arrangements of measuring sensors cause local error in the identification of moving force. Less number of measuring points will reduce the identification accuracy. If the condition is permissible, the measuring points should be arranged symmetrically, and increase the number of asymmetric measuring points can improve the identification accuracy.The research is supported by the National Natural Science Foundation of China under the contract number 10372041 and the Aeronautics Foundation under the contract number 02B52013.