Vehicle axle loads identification using finite element method

Existing methods on moving force identification are usually based on modal decomposition and are subject to modal truncation error in the dynamic responses. A new moving load identification method is presented basing on finite element method and condensation technique. The measured displacements are formulated as the shape functions of the finite elements of the structure which is modeled as a straight beam. The measured responses can be limited to a small number of master degrees-of-freedom of the structural system. Numerical simulations and experimental results demonstrate the efficiency and accuracy of the method to identify a system of general moving loads or interaction forces between the vehicle and the bridge deck. The number of master degrees-of-freedom of the system should be selected smaller than or equal to the number of measured points, and the identified results are relatively not sensitive to the sampling frequency, velocity of vehicle, measurement noise level and road surface roughness when a minimum of eight beam-column finite elements are used to model the bridge with measured information from three measuring points.