Heavy Vehicles speeds and dynamic loads are critical factors to bridge’s structure fatigue and rapid deterioration. The proposed paper addresses the modeling and simulation of dynamic loads of heavy vehicles, such as trucks and buses, on bridges and the effects of their speed on frequency response. In light of the above analysis, this paper proposes a method on how to minimize the structural vibrational of the combined vehicle and bridge system using semi-active suspension control. The vehicle dynamic load is minimized through an optimization scheme to yield an impact force with negligible bridge lateral deflection. The dynamic coupling between the vehicle and bridge are studied by examining the modes that are most likely to be excited by the vehicle speed and the roughness of the bridge surface.

The models consist of a bridge and a heavy vehicle. The bridge is modeled as continuos, lightly damped beam with different supports defined by the boundary conditions. The vehicle is a multi-degree of freedom (MDOF) system undergoing motion in one plane.

The methods of solution consist of a simple supported beam that closely simulates the first three beam modes of the Kishwaukee Bridge in Rockford, Illinois. The surface of the bridge generates some random excitation that serves as input to the vehicle, this is commonly known as the roughness of the bridge surface. The heavy vehicle is moving from left to right of the simply supported beam. The system is analyzed and optimized by semi-active control algorithms.

Close form numerical solution is obtained by a set of second order differential equations for the bridge-vehicle system. Experimental data obtained from the vibration testing of Kishwaukee Bridge (Illinois) were collected and validated with a FEM model. Only the first three beam modes were used due to the experimental limitations and the actual structural condition of the bridge. Using MATLAB a simulation is obtained by inputting the linear time-variant equations and optimizing the system.

Simulations of bridge vertical motion under different dynamic load conditions were examined and the results of bridge structure response were analyzed by comparing the effects of passive versus semi-active suspension controls. The method shows effectively how we can reduce the dynamic load force magnitude and its frequency of impact. The latter is usually associated with structural damage caused to the bridge.

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