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为了提高铁路房屋的抗震能力,分析地震动竖向分量对铁路房屋的地震响应性能,提出基于荷载—变形关系联合评估的地震动竖向分量对铁路房屋的地震响应评估模型。构建地震动竖向分量的力学响应评估模型,识别铁路房屋的地震屈服响应参数,采用荷载—变形关系和极限荷载结合的方法进行铁路房屋的地震屈服响应应力评估,分析地震动竖向分量对铁路房屋的响应。建立动量平衡方程和弯矩平衡方程,构建铁路房屋的地震响应的三阶段荷载—变形模式,实现地震动竖向分量对铁路房屋的地震响应性能评估模型的优化设计。测试结果表明,采用该模型能有效分析地震动竖向分量对铁路房屋的地震响应性能影响,Simulink仿真结果和有限元模拟结果的准确性较高,力学参数辨识性能优越,计算结果准确可靠。 相似文献
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地铁车站结构作为现代城市交通工程的重要组成部分,其抗震问题已成为城市工程抗震和防灾减灾研究的重点与难点。以深圳地铁3号线四期低碳城单拱大跨车站为研究对象,采用近场波动有限元方法,建立三维土-结构相互作用整体有限元分析模型。选取3条人工波和3条天然波作为输入地震动,分析水平单向地震动、水平与竖向双向地震动作用下单拱大跨地铁车站结构三维地震响应规律。研究结果表明,双向地震动作用下单拱大跨无柱结构及矩形框架有柱结构的水平位移及层间位移均略小于单向地震动作用下,但矩形框架有柱结构在竖向地震动作用下的中柱轴压比明显增加,说明单拱大跨车站结构可有效降低双向地震动作用下中柱轴压比变大的风险;双向地震动作用下的结构峰值弯矩大于单向地震动作用下,说明进行结构设计时应适当考虑竖向地震动作用的影响;单拱大跨无柱结构拱顶弯矩明显小于矩形框架有柱结构顶板跨中弯矩,改善了常规矩形框架结构顶板受力性能,但由于单拱大跨无柱结构缺少中柱竖向支撑作用,其底板及侧墙底部弯矩明显大于矩形框架有柱结构,尤其在双向地震动作用下更明显,因此单拱大跨无柱结构需加强底板及侧墙的厚度与配筋,以抵抗较大的弯矩响应。 相似文献
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采用动力时程法开展了拱形与矩形断面地铁车站结构地震反应的研究,分析了拱形断面和矩形断面地铁车站结构的关键截面在地震作用下的内力及变形的差异。结果表明:相比于矩形断面车站结构,拱形断面车站结构顶板边缘处和侧墙顶端的弯矩明显减小,车站侧墙顶端和顶板边缘处因承受弯矩过大而发生破坏的可能降低;内柱截面的轴压比明显减小,且与侧墙的轴压比差异显著减小,受力分配更为合理;拱形车站结构顶、底板的相对位移、内柱和侧墙的位移角相对较小。在已模拟的工况下拱形车站内力分布形式更为合理,水平变形相对较小,更有利于抗震。 相似文献
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浅埋地下车站结构中柱和地面高层结构底层中柱相似,地震作用下均需承担较大的竖向压力,易因变形能力不足发生脆性破坏。在某2层3跨地铁车站结构中引入地面高层结构中的分体柱设计理念,形成新型地下车站结构抗震体系。首先,通过拟静力推覆分析对比了传统钢筋混凝土中柱和分体柱在轴向压力作用下的水平变形特性;然后,建立了土-结构相互作用的拟静力推覆分析有限元模型,从关键截面内力、关键构件变形能力、关键构件塑性损伤等角度对比了传统钢筋混凝土中柱和分体柱的地下结构抗震性能差异。研究结果表明,将分体柱应用于2层3跨地铁车站结构中可提高整体结构抗震性能,其工作机理是避免分体柱承担过大的剪力和弯矩,并充分发挥分体柱竖向支撑能力和水平变形能力。 相似文献
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俯冲带地区竖向地震动的阻尼修正系数在工程结构抗震设计中起着重要作用。由于俯冲带地区的板块构造复杂,俯冲带地区的地震可划分为浅壳上地幔地震、板内地震和板间地震3种类型。为研究不同类型俯冲带地震的竖向地震动阻尼修正系数间是否具有显著差异而需要分别建立不同的阻尼修正系数模型,采用日本俯冲带地区的地震动数据,通过假设检验和构造差异指标的方式对不同类型地震的竖向加速度和位移反应谱的阻尼修正系数进行两两比较。结果显示:不同地震类型的竖向地震动阻尼修正系数在众多谱周期上存在统计意义和工程实际意义上的显著差异。该研究表明:研究俯冲带地区竖向地震动阻尼修正系数时需要考虑地震类型的影响。 相似文献
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长周期地震动作用下结构的位移响应呈现多次大位移往复、长持时的特点,体现了其区别于普通地震动的特殊作用特性。长周期地震动对结构的影响研究关键在于揭示长周期地震动作用特性对结构构件抗震性能的影响机理。首先,基于雨流计数法对长周期地震动和普通地震动作用下单自由度体系的弹塑性位移响应进行循环统计分析,阐明了长周期地震动的作用特性,并以此构建了考虑长周期地震动作用特性的拟静力加载制度。其次,通过对不同设计参数的RC柱进行传统加载制度和考虑长周期地震动作用特性加载制度作用下的低周往复加载,分析其抗震性能差异,揭示了长周期地震动作用特性对RC柱的影响。研究结果表明:长周期地震动表现为地震动强度需求小,结构弹塑性位移循环总数多,且以小弹塑性位移循环为主的地震动作用特性。长周期地震动作用特性显著影响RC柱的强度与刚度退化规律,且对低等级混凝土、高轴压比、高纵筋配筋率和高体积配箍率构件的刚度退化影响更为显著。 相似文献
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研究黄土丘陵河谷场地在地震作用下强地面运动特征的变化情况,可以揭示强震对该类场地上震害的触发机理。结合黄土高原的地貌特征,建立具有代表性的动力数值分析模型,通过输入不同幅值、频谱特性和持续时间的地震波,对起伏地形和覆盖黄土层共同影响下的黄土河谷场地进行地震反应分析。结果表明:黄土层和地形耦合作用控制了地表的PGA变化,使其趋于复杂,在同一输入波不同振幅作用下,与基岩河谷各测点相比,黄土覆盖河谷场地的地震动频谱幅值均有所增加,并且频谱主峰均向高频移动。在不同地震波输入下,场地不同部位的固有频率受地形高程和土层影响;而地震动大小和频谱幅值不仅与场地的基本频谱和地形起伏有关,也与输入地震波的频谱成分相关。输入波PGA与地震频谱特征都不变时,同一场地输出的地震频谱形状具有相似的特征,随着地震持时增长,能量向场地基本频率附近集中,从而可能导致场地上相应频率建筑物震动幅值增加,造成累积破坏。 相似文献
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Many studies have focused on horizontal ground motion, resulting in many coherency functions for horizontal ground motion while neglecting related problems arising from vertical ground motion. However, seismic events have demonstrated that the vertical components of ground motion sometimes govern the ultimate failure of structures. In this paper, a vertical coherency function model of spatial ground motion is proposed based on the Hao model and SMART 1 array records, and the validity of the model is demonstrated. The vertical coherency function model of spatial ground motion is also compared with the horizontal coherency function model, indicating that neither model exhibits isotropic characteristics. The value of the vertical coherency function has little correlation with that of the horizontal coherency function. However, the coherence of the vertical ground motion between a pair of stations decreases with their projection distance and the frequency of the ground motion. When the projection distance in the wave direction is greater than 800 meters, the coherency between the two points can be neglected. 相似文献
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The Influence of Strong-Motion Duration on the Seismic Response of Masonry Structures 总被引:2,自引:3,他引:2
Julian J. Bommer Guido Magenes Jonathan Hancock Paola Penazzo 《Bulletin of Earthquake Engineering》2004,2(1):1-26
The influence of strong-motion duration on the response of saturated soils is clearly recognised and accounted for in the
assessment of liquefaction potential. The degree to which duration of shaking influences damage to structures, however, remains
a topic of debate, with resolution of the issue complicated by the variety of definitions of duration and the variety of structural
behaviours, as well as the difficulty of decoupling the specific effect of duration from other features of the ground motion.
A suite of seven structural models with strength and stiffness degrading characteristics, designed to reflect the seismic
behaviour of masonry structures commonly encountered in many parts of Europe, are analysed using a suite of almost 500 strong-motion
accelerograms. Correlations are explored between the damage, measured in terms of the strength degradation, and a range of
strong-motion parameters, demonstrating that Arias intensity and spectral acceleration at the fundamental initial period of
the structure are both reasonably good damage indicators for such structures. A significantly improved correlation is obtained
by using the elastic spectral accelerations averaged over a period range from the initial period of the structure to a value
approximately three times greater, reflecting the stiffness degradation as the shaking progresses. The scatter in the correlation
is shown to be partially explained by differences in duration.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Irregular reinforced concrete (RC) buildings constitute a significant portion of the existing housing stock. A common type of irregularity is in the form of discontinuity in the vertical framing elements, which can exacerbate their seismic vulnerability. The design guidelines available in seismic design codes essentially cater to only regular buildings, and the safety of such buildings, even when the other guidelines of the codes are followed, is doubtful. This article evaluates the vulnerability of RC frame buildings with discontinuity in columns designed for modern seismic codes, in the form of seismic collapse capacity, collapse resistance against maximum earthquake demand level, and failure mechanism. The adequacy and limitations of the provisions of the seismic design codes are evaluated for such buildings. Analysis results show that the sequential analysis of buildings considering the construction staged effects, considerably affects the design and hence the collapse failure mechanism of even low- and mid-rise buildings. The results also underline the importance of strong column–weak beam design in the seismic performance of the floating column buildings. The vertical component of ground motion is also observed to be relatively more crucial in floating column buildings. 相似文献
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The paper presents a numerical investigation on the behaviour of reinforced concrete bridge piers subjected to horizontal seismic input. The scope of the investigation is to quantify the phenomenon of bending-induced axial vibrations. The results of a set of analyses conducted on single-column bent systems indicate that flexural cracking produces, in fact, significant axial vibrations. This effect is particularly relevant in squat elements with low axial force where the sway of the cross-sectional neutral axis under alternate bending causes strong hammering impulses at crack closure. Quantification of the effects related to this phenomenon can be determinant for the seismic assessment of existing bridges as well as for the design of new bridges. Likewise, performance and design forces of bearings and other anti-seismic devices can be estimated with more accuracy, based on the expected level of combined vertical and horizontal acceleration response on decks. The pier overall flexural response is not significantly altered by the fluctuation in axial force associated to these impulses, although local moment–curvature behaviour is, due to axial–bending interaction. Shear resisting mechanisms should be more sensitive to these vibrations and shear failure anticipated when a reduction in the axial contribution to the section shear capacity occurs. A tentative equation for the prediction of this flexural-induced vertical acceleration component is proposed based on simplified section kinematics and elastic impact analysis. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献