Dynamic Analysis and Optimization of Vehicle-Bridge Interaction System under Road Roughness and Time Variability of Element Interpolation Function

Vehicle-induced load, as one of the main excitation factors to bridge vibration and fatigue damage, plays a vital role in the analyzing of the vehicle-bridge interaction (VBI) system, but is still limited in both spatial location and numerical value. This paper presents an improved VBI system to investigate bridge vibration and vehicle vibration considering the coherent roughness and multiple lanes excitation. The vehicle and bridge subsystems and coherent roughness road are developed and are further integrated to form the VBI system based on the displacement relationship between wheels and the bridge. Further, the solution method of the VBI system is given, and the calculation platform is constructed. Meanwhile, the natural frequencies and mode shapes, as well as the mid-span displacement of the bridge, are verified with the results calculated in commercial software. Subsequently, the responses of the VBI system are investigated under different degrees of freedom of vehicle vibration, bridge damping ratio, road roughness class, multiple lanes, and velocity. It can be concluded that road roughness and velocity have a complex nonlinear relationship with the vibration of the VBI system. Finally, the Pareto strategy is applied to find the optimized value of suspension stiffness and damping, and the depth, unit mass, and elastic modulus of the bridge to minimize the system vibration. The results show an obvious improvement in the vibration of the VBI system.