Abstract:

A theoretical model was established for the interaetion of the multiple-vehicle and bridge system using the D'Alembert principle and the hypothesis of Euler-Bernoulli beam. The motion equation of the vehicle-bridge system was decoupled by the model analysis method. The decoupled motion equation expressed in the matrix form of the generalized coordinates was solved by the eigenvibration theory to get the frequencies of the bridge loaded by vehicles. For the highway bridges with small or medium span, their vibrations were excited usually by a single vehicle, and the vehicle will stay on the bridge after excitation, so analytical expressions of the frequencies of the bridge under the action of a single vehicle were derived. The effects of the location of vehicle, the stiffness of its suspension spring, the mass above and under the spring on the difference between the loaded frequencies and the eigenfrequencies of the bridge were discussed.

Key words: road engineering, bridge frequency, vehicle-bridge system, modal analysis method, decoupling of equation, eigenvibration theory