考虑震源机制的基础隔震结构反应谱研究

发布时间：2018-03-18 06:19

  本文选题：基础隔震结构　切入点：反应谱　出处：《兰州理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：基础隔震技术在过去二十多年来经历了多场大地震考验,成为国内外最热门的一项抗震技术,并且在包括我国在内的多个国家进入大面积推广阶段。反应谱对认识结构地震响应规律、校核结构分析结果有着重要的作用。反应谱的平均特性与震源机制,场地条件,震级,震中距等众多因素有关。其中,震源机制作为地震动的影响因素,不仅能够影响反应谱的谱值还能够影响反应谱曲线的形状,进而在结构的抗震设计中起到重要的作用。因此,本文围绕震源机制对隔震结构反应谱的影响展开了以下几方面的工作:(1)采用双自由度体系分析模型,研究谱的类型及上部结构阻尼比对隔震结构反应谱的影响。以ATC-63报告建议的选取原则选取了22条地震记录,以此为激励,利用状态空间法建立了隔震层的真谱与拟谱,并通过改变上部结构的阻尼比建立了不同阻尼比的反应谱。对比分析后,结果表明在研究隔震结构的反应谱时,不可用拟谱来代替真谱;以及在建立隔震结构的反应谱时,需确定上部结构的材料,从而确定上部结构阻尼比;(2)采用非比例阻尼,研究震源机制对隔震结构线弹性反应谱的影响。在Ⅱ类场地条件下,选取605条地震记录作为统计样本,按照地震记录类型及震源机制进行分组,运用状态空间法得到了在近场及远场地震作用下的加速度、位移及能量反应谱。采用标准化和平均化的方式研究了反应谱的特性,并运用分段线性拟合的方法给出了设计反应谱的表达式,该表达式可以反映震源机制等因素对反应谱的影响作用,最后通过对某实际基础隔震工程进行算例验证,将计算结果与抗震规范进行对比,结果表明本文提出的表达式更为安全、合理,可将其应用于基础隔震结构的抗震设计中;(3)采用Bouc-Wen模型描述隔震支座的非线性行为,研究震源机制对隔震结构弹塑性反应谱的影响。运用状态空间法及四阶龙格-库塔法得到近场及远场地震作用下的弹塑性反应谱,对反应谱特性进行分析之后,运用曲线拟合的方法给出了反应比谱(弹塑性反应谱与线弹性反应谱谱值比与周期的关系)的表达式。该表达式可反映震源机制等因素对反应谱的影响作用。利用该表达式可在线弹性反应谱的基础上快速获得结构的弹塑性响应。最后通过有限元模型进行了算理验证。结果表明:该式在进行隔震结构的弹塑性地震反应分析时具有良好的计算精度。
[Abstract]:In the past 20 years, the foundation isolation technology has been tested by many large earthquakes, and has become the most popular seismic technology at home and abroad. The response spectrum plays an important role in recognizing the seismic response law of structures and checking the results of structural analysis. The average characteristics of response spectra and the focal mechanism, site conditions, magnitude, etc. The focal mechanism, as an influential factor of ground motion, can not only affect the spectral value of the response spectrum but also the shape of the response spectrum curve, and thus play an important role in the seismic design of the structure. In this paper, according to the effect of focal mechanism on response spectrum of isolated structures, the following work is carried out: 1) A two-degree-of-freedom system analysis model is used. The types of spectrum and the effect of damping ratio of superstructure on response spectrum of isolated structures are studied. Based on the selection principle of ATC-63 report, 22 seismic records are selected, and the true spectrum and pseudo-spectrum of isolation layer are established by state space method. By changing the damping ratio of superstructure, the response spectra of different damping ratios are established. The results show that pseudo spectrum can not be used instead of true spectrum when studying the response spectrum of isolated structure, and when the response spectrum of isolated structure is established, the response spectrum of isolated structure can not be replaced by pseudo spectrum. The material of superstructure should be determined, and the damping ratio of superstructure should be determined by adopting non-proportional damping. The effect of focal mechanism on the linear elastic response spectrum of isolated structures is studied. 605 seismic records are selected as statistical samples under the condition of class 鈪，

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