【摘要】 基于PEER-NAG强震数据库,采用ANSYS分析软件、ANSYS-APDL语言和弯矩曲率关系计算程序,以高速铁路多跨简支梁桥为研究对象,建立了近断层脉冲型地震作用下的高速铁路桥梁全桥模型,考虑了轨道不平顺的影响,分析了结构的自振特性,计算了近/远断层地震作用下桥梁的弹塑性地震响应。计算结果表明,近断层方向脉冲型地震作用下的墩底的荷载-变形曲线呈现中间加强的特点,此时需要桥墩有更强的能量释放能力和较好的延性要求,相比远断层地震而言,近断层方向脉冲型地震作用下墩底梁体位移、墩顶位移以及墩底弯矩增大,且导致更大的塑形变形;远断层地震趋向于能量的逐渐释放过程并与较少的滞回环损伤疲劳相联系;由于近断层地震动方向脉冲效应的影响,在一些地震动的某些时段内,对结构破坏起控制作用的因素是速度或位移而不是峰值加速度;由于近断层地震较大的竖向地震动,导致梁体竖向挠度比远断层地震增加较多,《铁路工程抗震设计规范》等取竖向地震为横向的2/3左右,会导致竖向动力响应偏小,建议取竖向地震动的合理范围进行计算较为妥当。更多还原

【Abstract】 Based on the PEER-NAG Strong Ground Motion Database,the finite element model of a multi-span simply supported bridge was set up by means of ANSYS software,ANSYS-APDL language and compiled moment-curvature calculation program.The natural vibration properties of structure were analyzed,and the elastic-plastic seismic responses of the bridge subjected to near/far-fault ground motions were calculated.The calculation results show that,due to the hysteretic property of the near-fault directivity pulse-like earthquake,the load-deformation curve of pier bottom is characterized by the centrally strengthened hysteretic cycles at some point on the time-history curve of load corresponding to the pulse instant.The bridge piers are required to dissipate considerable input energy in a single or relatively few plastic cycles,which means that the ductility capacity of the piers should be improved.The displacement of girder and pier top and the moment at pier bottom under near-fault ground motion are greater compared with those under far-fault ground motion.The energy dissipation of the bridge system subjected to far-fault ground motion tends to gradually increase over a longer duration,causing an incremental build-up of input energy.Owing to the greater vertical earthquake action of near-fault earthquake,there is larger vertical deflection at the mid-span of girder.GB 50111-2006 Code for seismic design of railway engineering specifies that the vertical earthquake force can be taken as 67% of the lateral earthquake force,however,it’s advisable that more reasonable value of vertical earthquake acceleration should be utilized to carry out simulation calculation.更多还原