Research On Pounding Phenomenon For Continuous Girder Bridge And Prevention Measures

Bridges are one of the important transportation infrastructures, and its earthquake resistance and hazrad mitigation have been paid more attention. The bridges excited by strong earthquake occur pounding easily, which may cause some damages such as crashing at ends of girders, collision at expansion joints, and failure of bearing, even serious hazard as unseating of girders. The main contents of this dissertation are described as follows:Based on the comprehensive review of related literatures on pounding and falling-off prevention measures, state of the art of the analytical method of seismic responses for continuous girder bridges, the theoretical and experimental studies on pounding effects between adjacent bridge decks subjected to earthquake are reviewed and summarized.The computational theories and methods of pounding between adjacent bridge decks are reviewed and evaluated. An equivalent Kelvin impact model is proposed for seismic pounding analysis of bridge. The changing law of the impact stiffness and damping of the Kelcin impact model are simulated, and its rational value ranges are obtained for the practical engineering. The method of parameters used in SAP2000 is introduced.The pounding responses of the isolated elevated bridges under strong earthquake action are systematically investigated. Based on the proposed equivalent Kelvin impact model, and considering non-linearity of piers and soil-structure interaction,nonlinear finite element model for isolated simply-supported and continuous bridges are built up. According to pounding phenomenon at expansion joints for continuous girder bridge, the pounding model developed is used to evaluate the pounding effects between adjacent segments at expansion joints on seismic responses of continuous girder bridges subjected to longitudinal earthquake. The effects of some parameters such as adjacent bridge segments period ratio, natural periods, initial gap at expansion joints and non-linearity of piers on seismic pounding responses are then investigated.The evaluation of current restrainer and hinge seat width design procedures are presented, One of the falling-of prevention measures is introduced and evaluated by nonlinear time history analysis, which is proved to be effective.