【作者】 左琼；

【导师】 吴强；

【作者基本信息】 南京航空航天大学 ， 结构工程， 2009， 硕士

【摘要】 近断层地震动受到震级、断层距、震源机制和场地条件等因素的影响,表现出与一般的从远场地获得的地震动明显不同的性质,其中最显著的特点是由方向性效应和滑冲效应引起的速度脉冲型地面运动。本文对近断层地震动作用下SDOF结构的弹性反应谱、延性谱和近断层地震动输入能量特性进行了研究。文中介绍了中、日、美三国抗震规范分别对近断层问题的考虑。通过搜集具有速度脉冲波形近断层记录109条,按照我国规范中场地和地震分组类别进行分类,计算各分组的平均弹性反应谱。与规范设计反应谱的比较表明,近断层平均反应谱峰值大于规范给定的水平地震影响系数最大值;近断层各类场地的第三地震分组在中、长周期段反应谱也超出规范设计反应谱范围。为进一步研究近断层地区结构在塑性阶段的响应需求,文中建立SDOF结构弹塑性时程分析模型,代入109条具有速度脉冲的近断层地震动,考虑场地和地震分组因素的影响,计算了场地分组的平均延性需求谱,与吕西林、Wei-Jian Yi等提出的一般地震动等强度延性需求谱作对比,可以看出,近断层地震动显然具有更大的延性需求。通过构建瞬时输入能模型,分别计算SDOF结构在近断层地震动作用下保持弹性或进入塑性状态时的最大瞬时输入能,研究近断层速度脉冲型地震动的瞬时输入能特性和影响因素,试图从能量的角度解释速度脉冲与结构破坏的关系。结果表明,速度脉冲包含地震动的最大瞬时输入能,其值大小于与PGV/PGA比值成正比。更多还原

【Abstract】 Influenced by earthquake magnitude, fault distance, seismic source mechanism and site, characteristics of near-fault ground motion are different from far-fault, one of them is distinctly velocity pulse subject to the forward rupture directivity effect and the fling step effect. In this paper, elastic response spectra, ductility demand spectra and input energy of SDOF system in near-fault fields were investigated.Structure design to near fault in Code of China, Japan and America is separately discussed. 109 obviously velocity pulse records of the near-fault ground motion were collected and divided into groups considering soil conditions and design characteristic periods and each group average elastic spectra was calculated. By comparing with design response spectrum in Chinese Code, it is showed that the peak value of near-fault average response spectra is greater than maximum of seismic influence coefficient given by the Code. In mid-long period, response spectrum of the third group in all fields of near fault beyond obviously design response spectrum of the Code.In order to study on plasticity response demand to structure in near-fault fields, SDOF elastic- plastic time history analysis model was established, by imputing 109 obviously velocity pulse records of the near-fault ground motion and considering soil conditions and design characteristic periods, average ductility demand spectrum of all groups were calculated and compared with constant-strength ductility demand spectrum given by Xilin Lu and Weijian Yi, it is convinced that there is greater ductility demand in near-fault ground motions.By establishing instantaneous input energy analysis model, elastic or plastic maximum instantaneous input energy of SDOF system was separately computed.Characteristics of instantaneous input energy and influence factors were investigated as to interpret the relationship between velocity pulse and structure failure. The results indicates maximum instantaneous input energy lives at pulses time story and is proportion to the ratios of PGV/PGA.更多还原