【摘要】 总结了5.12汶川大地震中简支梁桥落梁震害及主要影响因素,发现除地震山体滑坡等地质灾害外,断层地表破裂、近断层地震动效应、桥台胸墙冲切破坏、防落梁构造措施单一及桥梁体型复杂等因素都是引起简支梁桥落梁震害的重要原因。提出了简支梁桥防落梁设计的基本理念及相关技术方案要点为允许墩梁间发生滑移,以降低桥墩承受的地震惯性力,以及盖梁提供允许的最大滑移长度及支座支承宽度,再辅助挡块或拉索限位器等共同防止落梁发生。最后结合现行规范,以拉索限位器为例给出了简支梁桥防落梁设计方法。更多还原

【Abstract】 The unseating damage to simply supported bridges and their main influencing factors during the Wenchuan earthquake are summarized.It is found that excepting the earthquake-induced landslide hazard,the earthquake surface rupture, near fault ground motion,punching shear failure of the abutment breast wall,the invalidity of the devices for preventing unseating damage to the bridges and the complex bridge types are main influencing factors leading to the unseating damage to the simply supported bridges.Basic seismic design idea and method to prevent unseating damage to simply supported bridges are presented in this paper,which include: (1) sliding between bridge girders and cap beams is allowed to reduce the seismic actions concentrated on the bridge piers;(2) cap beams with enough seating length are recommended for sliding between girder and pier to avoid unseating damage;(3) shear keys or cable restrainers should be used as added measures to prevent unseating damage.The design method for simply supported bridges with cable restrainers is illustrated in detail by using current seismic design code for bridges.更多还原