SEISMIC WAVE PASSAGE EFFECT’S INFLUENCES ON LONGITUDINAL SEISMIC POUNDING RESPONSE FOR CONTINUOUS GIRDER BRIDGES

In multiple continuous girders with piers of the same height, although natural periods of adjacent segments at expansion joints are the same, pounding between adjacent segments at expansion joints can be induced by seismic wave passage effect. In this paper, the seismic pounding responses between adjacent girder decks at expansion joints of continuous girder bridges due to seismic wave passage effect were investigated by the nonlinear time history analysis method. In analysis, contact element is used to model pounding and damper is used to describe the energy dissipation during collision. The results show that seismic wave propagation effect can cause relative displacements between adjacent bridge decks enough large to induce impact at expansion joints. The magnitude of pounding force depends on apparent velocity of seismic wave. Pounding can amplify relative displacements between adjacent bridge decks or piers and decks, which may even cause bridge decks to drop from piers and collapse. Therefore, influences of seismic wave passage effect on longitudinal seismic pounding response should be emphasized in seismic design and assessment for continuous girder bridges.