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深厚软弱地基上桩箱基础高层建筑地震反应特性数值模拟 总被引：4，自引：2，他引：4
根据土体—结构体系整体分析方法，以某26层桩箱基础框架—剪力墙高层建筑为例，探讨了深厚软弱地基与输入地震动特性对桩箱基础高层建筑地震反应的影响。通过数值模拟，得到以下结论：地震作用下高层建筑的地震反应与建筑物的地基条件与输入的振动特性等因素有关。一般地，SSI效应使上部结构的绝对加速度反应减小，但当输入加速度峰值较低时，建筑物部分楼层的绝对加速度反应有可能增大。在给定的输入地震动作用下，SSI效应使上部结构的楼层相对位移增大，但也可能存在减小的情况。分析结果表明：SSI效应对深厚软弱地基上桩箱基础高层建筑地震反应有很大的影响，在此类建筑的抗震分析中考虑SSI效应的影响是必要的。 相似文献
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2015年7月3日新疆皮山M_S6.5级地震灾区地处塔里木盆地南缘,该地自然条件恶劣,经济极为落后,灾区农村的民房除了抗震安居工程建设的房屋外,还有大量抗震性能较差的民居,在地震中受损严重,经济损失较大。灾区大部分位于山前溢出带,地下水位浅、地基土层软弱等场地条件对地震动有放大作用,震害影响范围较大。灾后重建中应继续加大安居富民工程的经费投入力度。灾区北部人口密集,地基土层软弱,工程地质条件差,建议在今后的安居富民建设中加强地基处理。 相似文献
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0 前言
地震是地下岩石受构造应力作用突然错动破裂而造成的地面强烈震动。地震造成灾害的原因绝大多数是因为房屋倒塌所致，而房屋的倒塌不仅取决于地震震级的大小和距离震中的远近，还取决于建筑物的地基稳固程度和抗震能力。在西部农牧区地域辽阔、经济相对落后，防震减灾工作十分薄弱，村镇规划未考虑地震安全问题，农村住宅基本不设防，农村住房的抗震性能蒡。据调查， 相似文献
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对2004年1月5日美国宇航局发布的火星轨道探测器拍摄的勇气号着陆点照片进行了研究,认为照片上的地形为陨石撞击火星表面留下的痕迹．详细计量了照片上陨石坑的数目和尺度．对陨石坑尺寸和数目之间的关系进行了研究．认为,火星陨石坑的分布具有碎形特征,并符合分形分布,分维数为1．7．和地球上其它岩石破碎相比,分维数较低．我们推测,撞击火星的陨石可能来源于同一块岩石的破碎。并且该岩石的破碎程度较低．其破碎过程应该和断层、断裂、节理以及风化等地质过程引起的破碎不同． 相似文献
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2015年7月3日新疆皮山MS6.5级地震灾区地处塔里木盆地南缘，该地自然条件恶劣，经济极为落后，灾区农村的民房除了抗震安居工程建设的房屋外，还有大量抗震性能较差的民居，在地震中受损严重，经济损失较大。灾区大部分位于山前溢出带，地下水位浅、地基土层软弱等场地条件对地震动有放大作用，震害影响范围较大。灾后重建中应继续加大安居富民工程的经费投入力度。灾区北部人口密集，地基土层软弱，工程地质条件差，建议在今后的安居富民建设中加强地基处理。 相似文献
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一、前言建筑物在强震作用下产生破坏,主要决定于建筑物本身的抗震性能和强地震地面运动的强度及特征这两个方面的因素。国内外历次大地震震害考察结果表明:孤突地形对强震地面 相似文献
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陨石坑或撞击坑(impact crater)是小行星、彗星和流星体等小天体超高速撞击行星及其卫星表明形成的凹坑或环状地质构造。由于大气层的保护,和其他星球相比,地球遭受到陨石撞击的可能性要低得多。可即便如此,据估计,在地球形成演化的过程中,出现过直径大于10 km的陨石撞击构造不少于1500个,而直径更小的陨石坑数量就更多了! 相似文献
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为了研究地震时地面运动加速度作用下高层房屋建筑深基坑支护承压结构的局部抗震性能，针对高层房屋建筑深基坑支护承压结构进行局部抗震性试验分析。采用有限元软件对某高层房屋建筑深基坑工程进行分析，构建高层房屋建筑深基坑支护承压结构有限元计算模型。利用地震模拟振动台，分别输入0.4g、0.5g、0.6g的地震时地面运动加速度，测试不同深基坑施工阶段和插入比地下连续墙深基坑支护承压结构的抗震性能，并研究不同地震烈度对深基坑支护承压结构位移的影响。通过振型分解反应谱法，获取高层房屋建筑深基坑支护承压结构位移以及加速度响应，实现高层房屋建筑深基坑支护承压结构局部抗震性能测试。试验结果表明，高层房屋建筑深基坑支护承压结构的抗震稳定性与深基坑开挖深度、插入比和地震烈度有关。其中，深基坑开挖深度和地震烈度与高层房屋建筑深基坑支护承压结构的抗震稳定性成反比，而插入比与高层房屋建筑深基坑支护承压结构的抗震稳定性成正比，且能够有效提高高层房屋建筑深基坑支护承压结构的抗震性能。 相似文献
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This paper investigates the seismic performance of moment-resisting frame steel buildings with multiple underground stories resting on shallow foundations. A parametric study that involved evaluating the nonlinear seismic response of five, ten and fifteen story moment-resisting frame steel buildings resting on flexible ground surface, and buildings having one, three and five underground stories was performed. The buildings were assumed to be founded on shallow foundations. Two site conditions were considered: soil class C and soil class E, corresponding to firm and soft soil deposits, respectively. Vancouver seismic hazard has been considered for this study. Synthetic earthquake records compatible with Vancouver uniform hazard spectrum (UHS), as specified by the National Building Code of Canada (NBCC) 2005, have been used as input motion. It was found that soil–structure interaction (SSI) can greatly affect the seismic performance of buildings in terms of the seismic storey shear and moment demand, and the deformations of their structural components. Although most building codes postulate that SSI effects generally decrease the force demand on buildings, but increase the deformation demand, it was found that, for some of the cases considered, SSI effects increased both the force and deformation demand on the buildings. The SSI effects generally depend on the stiffness of the foundation and the number of underground stories. SSI effects are significant for soft soil conditions and negligible for stiff soil conditions. It was also found that SSI effects are significant for buildings resting on flexible ground surface with no underground stories, and gradually decrease with the increase of the number of underground stories. 相似文献
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Farid Khosravikia Mojtaba Mahsuli Mohammad Ali Ghannad 《Bulletin of Earthquake Engineering》2018,16(9):3653-3673
This paper studies the effect of soil–structure interaction (SSI) on the seismic risk estimates of buildings. Risk, in this context, denotes the probability distribution of seismic monetary loss due to structural and nonstructural damage. The risk analysis here uncovers the probability that SSI is beneficial, detrimental, or uninfluential on seismic losses. The analyses are conducted for a wide range of buildings with different structural systems, numbers of stories, and foundation sizes on various soil types. A probabilistic approach is employed to account for prevailing sources of uncertainty, i.e., those in ground motion and in the properties of the soil–structure system. In this approach, probabilistic models are employed to predict the response, damage, and repair cost of buildings. To properly account for the ground motion uncertainty, a suite of nearly 7000 accelerograms recorded on soil is employed. It is concluded that structures on very soft soils are extremely likely to incur smaller losses due to SSI, which is in line with the common belief that SSI is a favorable effect for such systems. However, the results for buildings on moderately soft soils reveal a considerable probability, up to 0.4, that SSI has an adverse effect on the structure and increases the seismic losses. 相似文献
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将软土地层中地铁车站结构与周围土体地震时产生的水平加速度,以静态的水平加速度代替,使两者作用下结构内力最大值相等、出现部位相同,实现将动力问题转化为静力问题。结果表明,该方法能反映软土地层中两层三跨地铁车站的在地震时的动力响应,是适用于工程设计的简单、实用的数值方法。 相似文献
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软土具有高灵敏度、低强度等特性，在地震过程中极易产生震陷。基于OpenSees数值模拟方法对软土场地的震陷反应进行非线性动力有限元分析，通过改变地震动峰值加速度、频谱特性、输入方式来研究其对软土震陷的影响。结果表明，地震动峰值加速度对地基土的不均匀震陷有显著影响，地震动峰值加速度越大，震陷量显著增大，震陷影响深度更大，对水平地表造成的破坏范围也更大；地震动频谱特性对软土震陷有重要影响，当地震动卓越频率与场地自振频率相近时，其幅值越大，产生的震陷越严重；水平、竖向同时输入地震动的方式能更好地反映土体的振动及震陷响应。该研究成果对探索软土震陷的机理有一定的指导意义。 相似文献
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Takaji Kokusho Ryuichi Motoyama Hiroshi Motoyama 《Soil Dynamics and Earthquake Engineering》2007,27(4):354-366
Seismic wave energy in surface layers is calculated based on vertical array records at four sites during the 1995 Hyogo-ken Nambu earthquake by assuming vertical propagation of SH waves. The upward energy generally tends to decrease as it goes up from the base layer to the ground surface particularly in soft soil sites. Theoretical study on 1D multi-layers model to investigate the basic energy flow mechanism indicates that the energy at the ground surface can be smaller on softer soils due to high soil damping during strong shaking even if resonance effect is considered. A simple calculation for a shear-vibrating structure resting on foundation ground shows that induced strain in the structure is directly related to the energy or the energy flux of surface layers. Hence, a general perception that soft soil sites tend to suffer heavier damage than stiff sites should be explained not by greater incident energy but by other reasons such as degree of resonance. Furthermore, it is recommended that not only acceleration or velocity but also S-wave velocity should be specified at a layer where a design seismic motion is given, so that the seismic wave energy can clearly be quantified in seismic design practice. 相似文献
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基于土层结构的场地分类方法 总被引：5，自引：0，他引：5
本文在详细研究了不同土层结构在不同地震动输入下的地表反应谱的平台值和特征周期的基础上,提出了基于土层结构的场地分类的初步方案。本方案给出了在现行建筑抗震设计规范四类场地划分的基础上,进一步考虑软弱夹层在底部、中部和上部3种情况的场地分类方法。本文的结果对进一步推动场地分类的研究具有一定的意义。 相似文献
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The area located inside the São Sebastião volcanic crater, at the southeast end of Terceira Island (Azores), is characterized by an important amplification of ground motion with respect to the surrounding area, as clearly demonstrated by the spatial distribution of the damage that occurred during the Terceira earthquake (the strongest earthquake felt in the Island during the recent decades — 01/01/1980 — M = 7.2). Geological and geophysical studies have been conducted, to characterize the volcanic crater and understand the different site effects that occurred in the village of São Sebastião. The complexity of the subsurface geology, with intercalations of compact basalt and soft pyroclastic deposits, is associated to extreme vertical and lateral velocity contrasts, and poses a serious challenge to different geophysical characterization methods. The available qualitative model did not allow a complete understanding of the site effects. A new seismic campaign has been designed and acquired, and a single, geologically consistent geophysical model has been generated integrating the existing and new data. The new campaign included two cross-line P-wave seismic refraction profiles, four short SH-wave seismic reflection profiles, and seven multichannel surface wave acquisitions. The integration and joint interpretation of geophysical and geological data allowed mutual validation and confirmation of data processing steps. In particular, the use of refraction, reflection and surface wave techniques allowed facing the complexity of a geology that can pose different challenges to all the methods when used individually: velocity inversions, limited reflectivity, and lateral variations. It is shown how the integration of seismic data from different methods, in the framework of a geological model, allowed the geometrical and dynamic characterization of the site. Correlation with further borehole information, then allowed the definition of a subsoil model for the crater, providing information that allowed a better understanding of the earthquake site effects in the São Sebastião village. The new near-surface geological model includes a lava layer within the soft infill materials of the crater. This new model matches closely with the damage distribution map, and explains the spatial variation of building stock performance in the 1980 earthquake. 相似文献