不同支座形式对临猗黄河大桥地震响应影响研究

Study of Influence of Bearing Types on Seismic Responses of Linyi Huanghe River Bridge

以临猗黄河大桥主桥(112+14×128)m+(14×128+120)m高墩长联组合梁桥为背景,研究不同支座形式对高墩长联组合梁桥地震响应的影响。建立该桥有限元模型,考虑支座在强地震动作用下发生的滑动特性,采用非线性动力时程分析方法对摩擦摆支座和球型支座约束条件下桥梁的地震响应进行分析及损伤评价,从而提出合理的支座约束形式。结果表明:高墩长联桥梁中矮墩支座地震响应对地震动强度增长较为敏感,在桥梁抗震设计中应关注矮墩支座的地震响应;纵向支座位移响应大于横向支座位移响应,纵向墩底弯矩响应小于横向墩底弯矩响应;2种支座约束下的桥梁地震响应均满足两水准两阶段的抗震设防要求,只考虑支座位移响应峰值而不考虑支座自复位等属性时,球型支座更能有效降低高墩长联组合梁桥地震响应。

Different types of bearings can exert different effect on the seismic responses of composite girder bridge that consists of high-rise piers and long continuous units.Based on the main bridge of Linyi Huanghe River Bridge,which are supported on high-rise piers and contains two continuous units of 112 m plus 14×128 m and 14×128 m plus 120 m,a finite element model was built up to analyze the characteristics of seismic responses and damage evaluation of the bridge with friction pendulum bearings and the bridge with spherical bearings,respectively.The slip features of the bearings under intense ground motion were considered,and a non-linear dynamic time history analysis method was used.The possible damages of the bridge were predicted,and rational bearing types were proposed.The analysis indicates that the bearings on short piers of the bridge with high-rise piers and long continuous units are sensitive to the increase of ground motion intensity,which should be given great concern in the seismic design of bridge.The longitudinal displacement response of the bearing is stronger than the lateral displacement response,whereas the response of longitudinal bending moment in the pier base is weaker than the lateral bending moment response.The seismic performance of the bridge with either friction pendulum bearings or spherical bearings can meet the three-level(be intact in small earthquakes,repairable in medium-intensity earthquakes and do not collapse in strong earthquakes)and two-stage(in both the elastic stage and elastic-plastic stage)fortification demands.When the peak displacement rather than the resilience of the bearing is considered,the spherical bearing is more effective for the composite girder bridge with high-rise piers and long continuous units.