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.
Parametric study on performance of bridge retrofitted by unseating prevention devices [J]. 刘光晏,张国镇. Earthquake Engineering and Engineering Vibration . 2006(01)