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针对隧道的抗震安全性,借助有限元软件平台对其地震时程响应进行非线性有限元分析。利用弹性模型考虑混凝土隧道在循环荷载作用下的拉、压应力-应变关系,同时对土体采用MohrCoulomb模型,选用人工边界作为边界条件,以人工合成的多点地震加速度时程作为地震动输入,分别考虑一致输入、行波效应、相干效应及行波加相干效应对隧道的影响。分析结果表明,与一致激励的计算结果相比,非一致地震激励会显著增加隧道结构的内力和位移响应,从而对隧道抗震产生不利影响。研究结论可为长隧道结构的抗震设计和分析提供科学依据。 相似文献
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大跨度空间网格结构多维多点随机地震反应分析 总被引:4,自引:0,他引:4
本文建立了三维正交地震动多点激励下大跨度空间网格结构的随机地震反应分析方法,依据现行抗震设计规范的有关规定,确定了平稳随机地震动功率谱密度的模型参数。数值仿真分析了一柱距80m的正方形平板网架分别在一维地震动或三维地震动的一致激励、行波激励和考虑部分相干效应的随机激励下的地震反应。结果表明:考虑地震动的空间效应会很大程度地改变结构杆件的内力,其中控制杆件的内力增幅达到30%;地震动的行波效应对结构杆件内力的影响比随机地震动的部分相干效应的影响更大;三维地震作用比一维地震作用下结构杆件的内力大。由此得出结论,对于大跨度空间网格结构,必须进行多维多点地震激励下的随机地震反应分析。 相似文献
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多点激励下大跨度斜拉桥地震反应分析 总被引:2,自引:0,他引:2
大跨斜拉桥是交通运输的枢纽工程,一旦在地震中遭到破坏,将会造成巨大的直接和间接经济损失.由于大跨斜拉桥的跨度大,在地震中地震波到达不同桥墩的时间存在差异,这会对大跨斜拉桥的地震反应产生很大影响.因此,对大跨斜拉桥在多点输入下的反应开展研究,对进行正确有效的抗震设计,确保其抗震安全性具有非常重要的意义.本文分析了多点激励下大跨度斜拉桥的地震反应,并与一致激励下大跨度斜拉桥的地震反应进行了对比,研究了多点激励对大跨度斜拉桥地震反应的影响. 相似文献
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随机地震动场多点激励下大跨度桥梁地震反应分析方法 总被引:11,自引:3,他引:11
地震输入问题一直是工程结构抗震研究关注的焦点。对大跨度桥梁结构,考虑随机地震动场的多点激励而进行地震反应分析较为合理。本文结合大跨度桥梁抗震设计,系统地介绍了随机地震动场的模型以及随机地震动场多点激励下大跨度桥梁地震反应分析的方法。 相似文献
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以一座典型山区非规则梁桥为研究对象,建立了该桥梁多维多点激励下的多自由度动力计算模型,研究了该桥梁在多维多点激励下考虑支座摩擦滑移及结构碰撞等非线性因素时的抗震性能。研究结果表明:相比一维地震输入,多维地震可使结构的动力响应增加,桥墩底部弯矩需求增大;相比一致激励,多点激励可使得支座的位移需求增大,且地震波最后到达的桥墩上方支座位移最大;同时考虑多点激励和碰撞效应可使桥墩的弯矩需求增加;水平地震作用下,矮墩上部的支座容易滑动,且双向地震较单向地震更明显,三向地震输入较双向有所增强。因此,对山区非规则梁桥进行抗震设计时应有针对性地进行多维多点地震输入计算,找出结构的最大地震需求,以期指导设计。 相似文献
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地震动差动作用下大跨度空间网壳结构的反应分析 总被引:1,自引:0,他引:1
选取100m跨度的双层柱面网壳结构为研究对象,采用时程分析法,分别进行了结构在单向和三向地震行波输入作用下的反应分析,并针对多种视波速情况进行了研究,考查了地震动不同输入情况下结构杆件内力的分布特点,对其进行了对比分析,为大跨网壳结构的抗震设计提供了理论依据。研究表明,考虑行波效应会使结构部分构件内力有一定程度的提高,多维地震作用比单维地震作用下结构的杆件内力大。由此得出结论:对于大跨度空间网壳结构,应该进行多维非一致输入下的地震反应分析;为保证抗震安全,应对可能出现的地面视波速进行全面分析。 相似文献
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以上海浦东机场二期航站楼软土场地为例,应用二维土体模型和一维土体模型分别计算了深覆盖土层的地震反应,讨论了古河道对场地地震动参数的影响。此外,在二维土层地震反应分析中,进一步对比了基岩面地震波行波输入和一致输入下,场地地震动参数的差异。 相似文献
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A risk-targeted design spectral acceleration and the corresponding seismic design action for the force-based design of structures is introduced by means of two formulations. The first one called direct formulation utilizes the seismic hazard function at the site of the structure. Because the seismic action defined in the codes is often associated with a designated return period, an indirect formulation is also introduced. It incorporates a risk-targeted safety factor that can be used to define a risk-targeted reduction factor. It is shown that the proposed formulations give analogical results and provide an insight into the concept of the reduction of seismic forces for the force-based seismic design of structures if the objective is defined by a target collapse risk. The introduced closed-form solution for the risk-targeted reduction factor can be used to investigate how the target collapse risk, the seismic hazard parameters, the randomness of the seismic action, and the conventional parameters (ie, the overstrength factor and the deformation and energy dissipation capacity) affect the seismic design forces in the case of force-based design. However, collaborative research is needed in order to develop appropriate models of these parameters. In the second part of the paper, the proposed formulations are demonstrated by estimating the risk-targeted seismic design action for a six-storey reinforced concrete building. By verifying the collapse risk of the designed structure, it is demonstrated that the risk-targeted seismic action, in conjunction with a conventional force-based design, provided structure with acceptable performance when measured in terms of collapse risk. 相似文献
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Analysis of structural fuzzy random seismic response 总被引:2,自引:0,他引:2
Analysisofstructuralfuzzyrandomseismicresponse张跃,王光远YueZHANGandGuang-YuanWANG1)(DepartmentofCivilEngineeringTsinghuaUniversit... 相似文献
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工程结构等延性地震抗力谱研究 总被引:28,自引:7,他引:21
研究结构的非弹性反应谱对改进现有的结构抗震设计、发展基于性态的抗震设计以及了解复杂地面运动特性与结构动力特性之间的关系具有重要的意义。利用大量的单自由度在强震记录作用下的弹塑性动力时程分析,对等延性地震抗力谱这一重要的非弹性反应谱进行了较为详尽的研究,给出了四类场地条件(基岩、硬土、一般土和软土)下的平均等延性地震抗力谱,总结了对工程结构的抗震设计和研究具有实际意义的规律和特征,并分析了场地条件、结构的延性系数以及周期等对等延性地震抗力谱的影响,提出了新的拟合公式,其成果可供抗震研究和设计直接应用。 相似文献
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Ali Kavand S. Mehdi Zahrai 《地震工程与工程振动(英文版)》2006,5(2):235-243
Various types of passive control systems have been used to suppress the seismic response of structures in recent years. Among these systems, Tuned Liquid Column Dampers (TLCDs) dissipate the input earthquake energy by combining the effects of the movement of the liquid mass in the container, the restoring force on the liquid due to the gravity loads and the damping due to the liquid movement through orifices. In this study, the effects of seismic excitation characteristics such as frequency content and soil condition on the seismic performance of TLCDs are investigated using nonlinear time-history analyses. In this regard, among the past earthquake ground motion records of Iran, 16 records with different parameters were selected. In the structural model developed, the attached TLCD is simulated as a Tuned Mass Damper (TMD) having the same vibration period and damping ratio as the original TLCD. The numerical results show that the seismic excitation characteristics have a substantial role on the displacement reduction capability of TLCDs and they should be considered accordingly in the design of TLCDs. 相似文献
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This study is intended to evaluate the influence of dynamic bridge-train interaction (BTI) on the seismic response of the
Shinkansen system in Japan under moderate earthquakes. An analytical approach to simulate the seismic response of the BTI
system is developed. In this approach, the behavior of the bridge structure is assumed to be within the elastic range under
moderate ground motions. A bullet train car model idealized as a sprung-mass system is established. The viaduct is modeled
with 3D finite elements. The BTI analysis algorithm is verified by comparing the analytical and experimental results. The
seismic analysis is validated through comparison with a general program. Then, the seismic responses of the BTI system are
simulated and evaluated. Some useful conclusions are drawn, indicating the importance of a proper consideration of the dynamic
BTI in seismic design. 相似文献
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A stochastic approach has been formulated for the linear analysis of suspension bridges subjected to earthquake excitations. The transfer functions of various responses have been formulated while including the effects of dynamic Soil–Structure Interaction (SSI) via the use of the fixed-base modes of the structure. The excitation has been characterized by the ‘equivalent stationary’ processes corresponding to the free-field motions at each support and by an assumed coherency function between these motions. The proposed formulation considers the non-stationarity in the structural response due to sudden application of excitation by considering (i) the time-dependent frequency response functions, and (ii) the order statistics formulation for the peak factors in evolutionary response processes. The formulation has been illustrated by analysing the seismic response of the Golden Gate Bridge at San Francisco for two example excitations conforming to USNRC-specified design spectra. The significance of various governing parameters on the dynamic soil–structure interaction effects on the seismic response of suspension bridges has also been studied. It has been found that the contribution of the vertical component of ground motion to the bridge response increases with increasing soil compliance. Also, the extent to which the spatial variation of ground motion affects the bridge response depends on how significant the SSI effects are. Copyright © 1999 John Wiley & Sons Ltd. 相似文献