An idealized mechanical system is proposed to examine the response behaviors of the bridge system consisting of several simple spans. The system is modeled as the multiple oscillators, and individual oscillating units are composed of 3 degree-of-freedom system, which are translational motion of superstructure, and translational and rotational motions of foundations. The corresponding equations of motion are then derived and the effects of pounding and restrainers are analyzed. The pounding is found to affect the global motion of the bridge. It is found that the pounding may increase or decrease the relative motions between adjacent units according to the given conditions. The maximum relative displacements occur between the abutment and nearby girder. The restrainers are found to reduce the relative displacements efficiently lowering the probability of span failures.