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本文分析了TMD(Tuned mass damper)在刚性地基和柔性地基情况下的减震控制机理,以某6层钢筋混凝土框架结构为研究对象,分别考虑了土-结构动力相互作用对无TMD控制结构的影响,场地条件对TMD减震控制性能的影响和土-结构动力相互作用对TMD减震控制性能的影响。通过分析得出TMD控制系统的减震效果除了与输入地震动特性有关外,还与场地条件、上部结构和基础的动力特性等因素有关。如果土-结构动力相互作用体系的自振周期远离输入地震动的卓越周期,则相互作用体系的地震响应较小。地基土越软,框架建筑结构层间相对位移地震响应也就越小。如果考虑土-结构动力相互作用效应的影响设计TMD调频系统的自振周期,则TMD的控制效果会有一定程度的提高。 相似文献
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《地震工程与工程振动》2017,(1)
本文实现了SH波斜入射时三维结构-土-结构动力相互作用分析。半无限土体采用集中质量显式有限元结合透射人工边界进行分析;结构经有限元离散后,采用Newmark隐式积分方法进行分析;刚性基础的响应采用显式积分方法计算。通过算例,分析了相邻结构存在与否、结构间距、结构大小、结构前后位置、SH波入射角度对基础和结构地震响应的影响。结果表明:(1)SH波入射角度对结构-土-结构相互作用有较大影响,随着入射角度的增大,高频段的干涉和遮挡效应较为明显;(2)两相邻结构中,大结构对小结构的影响较大,小结构对大结构影响较小;(3)当考虑结构-土-结构相互作用时,不仅结构自身各个自由度之间的运动存在耦合,而且通过土体的联系,相邻结构的各个自由度之间也存在耦合。(4)通过地震记录或地脉动测试获取结构自振特性时,应考虑相邻结构的影响,避免混淆。 相似文献
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在桩-土-结构弹塑性动力相互作用模型研究的基础上,设计了考虑场地类别、输入地震动等因素的基于相互作用模型的多层和高层钢筋混凝土框架结构算例,分析了桩-土-结构相互作用对结构弹塑性变形特性的影响,并与不考虑相互作用的结构底部固端模型的计算结果进行了对比。分析表明:相互作用对结构的弹塑性变形的影响不容忽视,考虑相互作用后梁柱塑性铰出现的程度降低;结构底部位移增加而顶部位移减小;薄弱层的层间位移可能增加而其余层的层间位移则减小。现行的结构弹塑性变形验算方法未考虑土-结构相互作用的做法的合理性值得进一步评判。 相似文献
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为了研究设备所在楼层位置对设备-结构相互作用的影响,以某高层钢框架为例,将设备分别放置于结构顶层和底层设计了2种设备-结构体系模型,然后利用ANSYS有限元分析软件对整体模型进行地震响应时程分析。分析结果表明:在El Centro波、Taft波和人工波作用下,当设备频率与结构基频调谐时,设备-结构相互作用会令结构动力响应减小而设备动力响应显著增大;设备-结构相互作用的大小与设备所在楼层密切相关:顶层设备与结构间的相互作用比底层更加剧烈,这与位于不同楼层的设备间等效质量以及底端输入激励频谱的差异有关。 相似文献
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通过对群桩-土-偏心结构相互作用体系振动台试验,分析了结构偏心效应对相互作用体系自振特性、地基振动和桩基变形的影响规律。试验结果表明:地基土的加入使得相互作用体系前两阶自振频率相差增大,平扭振动耦联程度降低,体系阻尼比明显增加;结构偏心效应增大了角桩的加速度响应,高出同深度边桩测点10～15%,桩身振动频率特性较场地土有明显差别;角桩变形幅度较边桩更为突出,桩长范围内角桩应变峰值始终大于边桩测点,两者相差在桩顶附近达到最大;桩间土承担了部分扭转效应,角桩较边桩应变增幅约为对应位置筏板位移增幅的一半;土的动力放大特性与以往研究规律相近,结构偏心效应对地基整体振动产生的影响不很明显;桩土界面动力响应与筏板平动位移时程相对应,且随深度的增加而逐步增大。 相似文献
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《地震工程与工程振动》2016,(1)
采用边界元法结合斜面分布荷载格林函数计算了水平层状半空间中的埋置刚性基础在入射P波,SV波和SH波作用下的动力响应,研究了场地动力特性对土-基础动力相互作用的影响。分析表明,层状半空间中土-基础相互作用的机理和均匀半空间有很大区别,且层状半空间中的土-基础相互作用大于均匀半空间中的土-基础相互作用;基础动力特性和场地动力特性较为相似,且土层厚度和刚度对基础动力响应的影响较大,而基础质量的影响则较小;土-基础相互作用的基本规律和土-基础-地上结构相互作用的基本规律相差较大,而与土-地下隧道相互作用则较为相似。 相似文献
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复杂结构-桩-土振动台模型试验数据分析 总被引：2，自引：0，他引：2
本文从分析复杂结构-桩-土振动台模型试验数据入手,用加速度动力系数、最大位移、最大正应变、最大动土压力等指标对结构的地震响应全面分析,并对比桩、地下结构、地上结构的不同响应,研究发现:结构不同部分最大地震响应发生的频率不尽相同,且受地震动频谱特性及自身频率影响,天津波加载时结构的地震响应较大;地表以下,当震级较小时,土-结构对地震动起放大作用,随着震级的增加,对地震动放大作用减缓甚至减小;最大位移随结构高度增加逐渐增大,在桩与地下结构交界处和地表处,位移改变较大;地下结构柱、桩最大正应变呈中间大、两头小分布;最大动土压力随着深度增加呈两头大、中间小分布,且地表处最大;总的土压力受最大动土压力影响较大,随深度增加有先降低、后增大的趋势. 相似文献
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确定结构基底等效输入地震动的简化方法 总被引：1，自引：0，他引：1
本文用理论和实例计算分析了土与结构间的动力相互作用。根据基底等效输入的地震动相对入射地震动的传递函数特点研究出了一种等效输入的方法，该方法比较好地反映了场地和结构的动力特性对基底等效输入的影响。为利用刚性基底假设理论来分析土-结构动力相互作用提供了一种方法。 相似文献
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海上风机结构系统频率是海上风机结构和基础设计考虑的关键因素之一,桩-土相互作用对海上风机结构系统频率影响显著。基于欧拉-伯努利梁理论和传递矩阵方法,考虑水-桩-土相互作用及塔筒变截面特性,建立单桩式海上风机结构系统横向振动自振频率特征方程;将桩-水相互作用等效为附加质量、桩-土相互作用等效为线性弹簧,变截面塔筒等效为多段均匀梁,利用MATLAB中fsolve函数求解固有频率。通过与有限元分析结果进行对比,验证本文方法精度与有效性,并将本文方法应用于实际工程中,研究桩基础埋深、上部质量、转动惯量和桩-水相互作用对单桩式海上风机结构系统自振频率的影响。 相似文献
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Cristina Medina Guillermo M. Álamo Juan J. Aznárez Luis A. Padrón Orlando Maeso 《地震工程与结构动力学》2019,48(7):772-791
Although the seismic actions generally consist of a combination of waves, which propagates with an angle of incidence not necessarily vertical, the common practice when analyzing the dynamic behavior of pile groups is based on the assumption of vertically incident wave fields. The aim of this paper is to analyze how the angle of incidence of SV waves affects the dynamic response of pile foundations and piled structures. A three-dimensional boundary element-finite element coupling formulation is used to compute impedances and kinematic interaction factors corresponding to several configurations of vertical pile groups embedded in an isotropic homogeneous linear viscoelastic half-space. These results, which are provided in ready-to-use dimensionless graphs, are used to determine the effective dynamic properties of an equivalent single-degree-of-freedom oscillator that reproduces, within the range where the peak response occurs, the response of slender and nonslender superstructures through a procedure based on a substructuring model. Results are expressed in terms of effective flexible-base period and damping as well as maximum shear force at the base of the structure. The relevance and main trends observed in the influence of the wavefront angle of incidence on the dynamic behavior of the superstructure are inferred from the presented results. It is found that effective damping is significantly affected by the variations of the wave angle of incidence. Furthermore, it comes out that the vertical incidence is not always the worst-case scenario. 相似文献
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The problem of the through-soil coupling of structures has puzzled the researchers in the field for a long while, especially regarding the varied performance of identical, adjacent buildings in earthquakes. The phenomenon of structure-soil-structure interaction (SSSI) that has often been overlooked is recently being recognized: The possible effects in urban regions are yet to be thoroughly quantified. In this respect, the goal of this work was to rigorously investigate the interacting effects of adjacent buildings in a two-dimensional setting. Detailed finite element models of 5-, 15-, and 30-story structures, realistically designed, were used in forming building clusters on the viscoelastic half-space. Perfectly matched layers were used to properly define the half-space boundaries. The interaction of the structure and the soil medium because of the presence of spatially varying ground motion on the boundary of excavated region was considered. The effects of the foundation material and the distance between adjacent buildings on the structural behavior of the neighboring buildings were investigated using drift ratios and base shear quantities as the engineering demand parameters of interest. The effects of SSSI, first investigated in the frequency domain, was then quantified in the time domain using suites of appropriate ground motions in accordance with the soil conditions, and the results were compared with the counterpart SSI solution of a single building. The results showed that, for identical low-rise structures, the effects of SSSI were negligible. Yet, neglecting SSSI for neighboring closely spaced high-rise structures or building clusters with a large stiffness contrast was shown to lead to a considerable underestimation of the true seismic demands even compared with solutions obtained using the rigid base assumption. 相似文献
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Influences of type of wave and angle of incidence on seismic bending moments in pile foundations 
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下载免费PDF全文 When analysing the seismic response of pile groups, a vertically‐incident wavefield is usually employed even though it does not necessarily correspond to the worst case scenario. This work aims to study the influences of both the type of seismic body wave and its angle of incidence on the dynamic response of pile foundations. To this end, the formulation of SV, SH and P obliquely‐incident waves is presented and implemented in a frequency‐domain boundary element‐finite element code for the dynamic analysis of pile foundations and piled structures. Results are presented in terms of bending moments at cap level of single piles and 3 × 3 pile groups, both in frequency and in time domains. It is found that, in general, the vertical incidence is not the most unfavourable situation. In particular, obliquely‐incident SV waves with angles of incidence smaller than the critical one, a situation in which the mechanism of propagation of the waves in the soil changes and surface waves appear, yield bending moments much larger than those obtained for vertically‐incident wavefields. It is also shown that the influence of pile‐to‐pile interaction on the kinematic bending moments becomes significant for non‐vertical incidence, especially for P and SV waves. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Many of the numerical techniques used for seismic zonation studies treat one-dimensional structural models and/or the incidence of plane polarized body waves. These techniques are often not adequate for laterally heterogeneous structures and for sources that are not located beneath the site of interest. In such cases a more rigorous treatment of the combined effects of the source, the path and the site response is needed. This can be accomplished with a hybrid approach combining modal summation and the finite-difference technique. To demonstrate the differences between these techniques, the ground motion in the city of Benevento (Italy) is modelled. We first compare the results obtained with one-and two-dimensional structural models for vertical incidence of plane polarized body waves. These results are then compared with those obtained with the hybrid approach for two-dimensional structural models.The comparisons have allowed us to find important differences in the response obtained with the different modelling techniques. For the same site, these differences consist of strong variations in amplitude and in the shape of the spectral amplifications. For a seismic source which is not located beneath the site, vertical incidence of waves significantly overestimates the local hazard in a laterally homogeneous structure. For a laterally heterogeneous area, we can conclude that one-dimensional modelling fails to estimate the seismic hazard, whereas for a seismic source which is not located beneath the site of interest, two-dimensional modelling with vertical incidence of plane polarized body waves may not allow reliable estimates to be made of the frequency bands at which amplifications occur. The results obtained for two-dimensional structural models are used for a zonation of the city of Benevento. 相似文献
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The dynamic through–soil interaction between nearby pile supported structures in a viscoelastic half-space, under incident S and Rayleigh waves, is numerically studied. To this end, a three-dimensional viscoelastic BEM–FEM formulation for the dynamic analysis of piles and pile groups in the frequency domain is used, where soil is modelled by BEM and piles are simulated by one-dimensional finite elements as Bernoulli beams. This formulation has been enhanced to include the presence of linear superstructures founded on pile groups, so that structure–soil–structure interaction (SSSI) can be investigated making use of a direct methodology with an affordable number of degrees of freedom. The influence of SSSI on lateral spectral deformation, vertical and rotational response, and shear forces at pile heads, for several configurations of shear one-storey buildings, is addressed. Maximum response spectra are also presented. SSSI effects on groups of structures with similar dynamic characteristics have been found to be important. The system response can be either amplified or attenuated according to the distance between adjacent buildings, which has been related to dynamic properties of the overall system. 相似文献
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The interaction between membrane structures and their environment can be either static or dynamic. Static interaction refers
to interaction with static air, while dynamic interaction refers to wind and its effects. They can be evaluated by two parameters,
added mass and radiation /aerodynamic damping, which are experimentally investigated in this study. The study includes the
effects of both the static and dynamic interaction on structural dynamic characteristics, and the relationship between the
interaction parameters and the covered area of a membrane structure for the static interaction and the relationship between
the interaction parameters and wind direction and speed for the dynamic interaction. Experimental data show that the dynamic
interaction is strongly correlated with the structural modes, i.e., the interaction of the symmetric modes is much larger
than the anti-symmetric modes; and the influence of the dynamic interaction is significant in wind-induced response analysis
and cannot be ignored. In addition, it is concluded that the structural natural frequency is remarkably decreased by this
interaction, and the frequency band is significantly broadened. 相似文献
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地震动入射角度对地下结构地震响应的影响 总被引：1，自引：0，他引：1
考虑土-结构接触面效应和场地初始静应力影响,基于大型商用有限元软件ANSYS和粘弹性人工边界条件,采用动力松弛法的分析思路,建立了一种地震动斜入射条件下地下结构的接触非线性动力反应分析模型和方法,并讨论了地震动入射角度对地下结构动力反应的影响。结果表明：地震波斜入射使得结构的整体反应发生明显变化;随着入射角度的增加,节点的水平向应力反应明显增大,竖向应力峰值较小,增大程度也相对较小;节点的位移峰值随输入加速度峰值的增大也有一定的变化。因此,在分析近源地震作用下的地下结构动力响应时,需要考虑地震动的非一致输入问题。 相似文献
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Studies of structural responses and damage to high-frequency blast motion are very limited. Current practice uses some empirical allowable ground vibration limits in assessing structural performance. These empirical limits overlook the physical parameters that govern structural response and damage, such as the ground motion characteristics and inherent structural properties. This paper studies the response of RC frame structures to numerically simulated underground blast-induced ground motions. The structural response and damage characteristics of frame structures to ground motions of different frequencies are investigated first. The effects of blast ground motion spatial variations and soil–structure interaction on structural responses are also studied. A suitable discrete model that gives accurate response prediction is determined. A damage index defined based on the accumulated plastic hinge rotation is used to predict structural damage level. Numerical results indicated that both the low structural vibration modes (global modes) and the first elemental vibration mode (local) might govern the dynamic structural responses depending on the ground motion frequency and structural response parameters under consideration. Both ground motion spatial variations and soil–structure interaction effects are prominent. Neglecting them might yield inaccurate structural response prediction. The overall structural response and damage are highly ground motion frequency dependent. Numerical results of structural damage are also compared with some test results obtained in a previous study and with code specifications. Discussions on the adequacy of the code allowable ground vibration limits on RC frame structures are also made. 相似文献