Vibration control of simply supported beams under moving loads using fluid viscous dampers

In this article, a new alternative for reducing the resonant vibration of simply supported beams under moving loads is presented and numerically evaluated. The strategy proposed is based on the use of linear fluid viscous dampers that connect the beam carrying the loads (main beam) and an auxiliary beam placed underneath the main one. Our research study shows that the resonant response of the main beam can be drastically reduced with this type of device. Firstly, the main beam,equipped with the damping system is subjected to a sinusoidal excitation and analysed with a view to discovering the dampers which minimise the overall dynamic response at resonance. In this way, a closed-form expression of the optimal damper constants is obtained for minimising the vertical acceleration, and a slightly different one for minimising the vertical displacement. These expressions are then applied to real bridges subjected to railway traffic, and their adequacy is proven for a wide range of circulating velocities. Finally, we compare the performance of the original structure with the performance of the one equipped with these optimal dampers. The results of our study prove their effectiveness and technical feasibility. The methodology proposed has potential applications for the reduction of the response of railway bridges subjected to the transit of high-speed trains. (c) 2006 Elsevier Ltd. All rights reserved.