Analysis of Vehicle-Induced Vibration Response and Impact Coefficient for Composite Truss Bridge with Partially Concrete-Filled Rectangular Steel Tube Members

An innovative method is presented in this paper for the solution to the vehicle–bridge coupled vibration problem for highway bridges using the ANSYS software. By comparing the calculation results of this paper with those of the literature, the correctness and reliability of this method were verified. Taking a new structural bridge (composite truss bridge with partially concrete-filled rectangular steel tube members) as the engineering foundation, the vehicle-induced responses of the lower chords of the main truss were compared and analyzed in two states: partially concrete-filled and non-filled. Accordingly, the concept of the concrete filling coefficient was further developed, and the vehicle-induced responses of the new structural bridge and its impact coefficients were solved and analyzed for different concrete filling coefficients. The results showed that after partially filling the new structural bridge with concrete, the vertical dynamic stiffness of the bridge could be improved, the vehicle-induced response could be reduced, and the fatigue resistance could be increased. It is recommended that the concrete filling coefficient of the new structural bridge be within the range of 0.35 to 0.5. Under different concrete filling coefficients, the fitting results of the impact coefficient of the bridge submit to the extreme value distribution type-I, and the suggested value of the impact coefficient is 0.223 at a 95% assurance rate. For this new structural bridge, the impact coefficient values in Chinese specification are less than the suggested value of 0.223, which should be taken into account by bridge designers.