Dynamic response analysis of suspended beams subjected to moving vehicles and multiple support excitations

For dynamic analysis of a suspended beam subject to the simultaneous action of moving oscillators and multiple support motions, we need to deal with nonlinear interaction problems in conjunction with time-dependent boundary conditions. In this study, the total response of the suspended beam is decomposed into two parts: the pseudo-static response and the inertia-dynamic component. Then, the pseudo-static displacement is analytically obtained by exerting the support movements on the suspended beam statically and the governing equations in terms of the inertia-dynamic component as well as moving oscillators are transformed into a set of coupled generalized equations by Galerkinʹs method. Instead of solving the coupled equations containing pseudo-static support excitations and moving oscillators, this study treats all the nonlinear coupled terms as pseudo forces and solves the decoupled equations using the Newmark method with an incremental-iterative approach. Numerical investigations demonstrate that the present solution technique is available in dealing with the vehicle/bridge interaction problem involving multiple support motions, and that appropriate adjustments of cable sag ratios subject to the condition of identical bridge frequencies are beneficial for mitigating the earthquake-induced vibration of suspended bridge/vehicle coupling system.