Vibration of arch bridges due to moving loads and vertical ground motions

This paper is focused on the vibration in a two-hinged arch bridge subjected to the combined action of moving loads and vertical ground excitations. The arch bridge is modeled as a flat-rise parabolic arch with constant sectional properties along the horizontal axis of span, and the train loadings over it as a sequence of identical lumped loads with constant intervals. To investigate such a dynamic problem, a single span bridge with non-homogeneous time-dependent boundary conditions, the quasi-static decomposition method is employed to decompose the deflection response of the arch into quasi-static deflection and the dynamic component of deformation. Then one can analytically derive the closed form solution of quasi-static deflection for the arch bridge shaken by vertical support excitations. Throughout the parameter studies, the present results indicate that the maximum acceleration response on the arch bridge relates to: (1) the vibration mode that has been excited, (2) the time lag until moving loads begin to enter the bridge during the acting time of earthquakes, and (3) the rise to span ratio of the arch.