考虑土与结构相互作用效应的结构减震控制大型振型台模型试验研究

本文设计并完成了考虑土与结构相互作用的结构减震控制大型振动台模型试验，通过对四种结构形式的对比试验。探讨了土与结构相互作用（SSI）效应对结构地震反应的影响以及调谐质量阻尼器（TMD）在刚性和柔性地基条件下对主体结构的减震效应。通过比较同一地震动作用下主体结构在刚性和柔性两种地基条件下的地震反应，可知：SS效应具有降低和提高结构减震控制效果的双重作用，其综合效果与输入地震动的频谱特性，加速度峰值大小有关。由于SSI效应在结构地震反应中发挥着双重的作用，因而使得基于刚性地基假定了设计的TMD减震控制系统在柔性地基条件下的控制效果不太理想，甚至会出现负面效应。本文还探讨了在生地基条件下影响减震控制效果的一些因素。     

土与结构动力相互作用体系振动台模型试验研究

设计并完成了土与结构动力相互作用体系的大型振动台模型试验，通过将同种加载条件下的刚性地基和柔性地基上结构地震反应进行对比，分析了SSI效应对一幢十层框架结构地震反应的影响。由试验结果可知：在SSI效应作用下，基底输入地震动的强度和频谱特性发生了显著的变化；由于SSI效应的作用，刚性地基和柔性地基上的结构地震反应存在较大差别，且在一定条件下，SSI效应对结构地震反应能起到减震作用。     

主次结构减震特性研究

本文探讨了主次结构的减震特性以及土－结构相互作用对减震效果的影响，在一定条件下，次结构对主结构有减震作用，其减震效果与主次结构的刚度比和质量比、次结构的阻尼和输入地震动的特性有关，对于多层建筑，次结构既可能减小主结构的加速度，也可能减小其相对位移，对于高层建筑、则主要是减小主结构的相对位移，对于中软至弱地基条件，ＳＳＩ效应明显降低高层建筑的加速度反应；对于中等地基条件，ＳＳＩ效应显著降低次结构对高     

考虑土-结构动力相互作用的TMD结构减震控制

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。     

SSI效应对粘弹性阻尼结构减震效果的影响分析

本文以一单跨7层框架结构为研究对象,对不同场地和地震波输入条件下的粘弹性阻尼结构进行了二维有限元时程分析,探讨了SSI（土-结构动力相互作用）效应对粘弹性阻尼结构减震效果的影响。分析结果表明：①在硬土和稍硬土地基条件下,SSI效应明显降低了结构的楼层位移峰值,若在抗震设计中对客观存在的SSI效应加以考虑,设置较少数量的阻尼器（与刚性地基假定条件下确定的阻尼器数量相比）就能使结构的实际地震位移反应满足基于刚性地基假定的地震位移控制目标;②粘弹性阻尼结构的减震效果与场地条件、输入地震动特性密切相关;③与刚性地基相比,SSI效应使粘弹性阻尼结构的减震效果明显降低,且地基越软,降低幅度越大。因此,在实际的工程设计中,应当充分考虑SSI效应,对粘弹性阻尼结构的减震控制效果进行合理的评价,并针对不同的场地条件选用合适的阻尼器类型和性能参数,才有可能达到预期的减震控制效果。     

考虑土与结构相互作用效应的非弹性结构主动抗震控制研究

本文以一幢六层框架结构为研究对象，分析了土与结构相互作用效应对脉冲发生器和锚索两种控制系统的主动抗震控制效果的影响。结果表明：脉冲控制比锚索控制更为有效：在软土地基条件下，ＳＳＩ效应有可能使结构主动锚索控制失效；与刚性地基假定的结果相比，ＳＳＩ效应将显著降低脉冲控制所需的控制力，地基越软，降低的幅度越大，可达１／３￣１／２；若结构抗震设计时设及ＳＳＩ效应的影响，则按刚性地基假定需设置的主动抗震控制     

TLD控制的钢结构振动台模型试验研究

本文通过钢结构的振动台模型试验,研究了在刚性地基条件下矩形调谐流体阻尼器(TLD)对结构地震反应的减震机理和减震效果,为进一步研究土-结构相互作用对结构TLD减震控制效率影响的振动台模型试验提供对比数据。试验结果表明,在水箱中设置铁丝网有助于提高TLD的减震效率,地震动的频谱特性和峰值加速度大小对TLD的减震效率有重要影响。     

深软场地上考虑土-结构相互作用的斜拉桥被动控制分析

结合某一工程,采用软土粘塑性动力本构模型,在合理模拟深软场地非线性基础上讨论土-结构动力相互作用对斜拉桥被动控制效果的影响.利用软件ABAQUS建立了深软场地-桩基-斜拉桥三维有限元模型,作为对比,建立了深软场地上不考虑土-结构动力相互作用的常规刚性地基模型,通过时程分析法计算斜拉桥地震反应.计算结果表明:深软场地上考虑土-结构动力相互作用后,斜拉桥被动控制效果下降;在刚性地基上取得良好减震效果的被动控制手段若照搬至柔性地基上,可能不仅减震效果不好,还会给桥梁结构增加内力负担.     

土-桩-钢结构-TLD系统振动台模型试验研究

通过系列振动台模型试验,研究土-结构相互作用对结构TLD减震控制影响。文中首先提出试验模型设计中应考虑的几个主要问题及解决方法,然后介绍土-桩基础-钢结构-TLD相互作用体系的试验成果,分析TLD的减震效果,最后与刚性地基上钢结构TLD减震试验结果相比较,揭示土-结构相互作用对TLD减震效率的影响特点。试验结果表明:土-结构相互作用使得TLD减震效率降低,这一削减作用受到输入地震动的频谱特性和强度的影响。因此,对于建在土层场地上的结构进行TLD减震设计时,应充分重视工程场地条件和地震动特性等实际情况。     

高层建筑结构-地基动力相互作用效果的振动台试验对比研究

本文通过对高层建筑结构－地基动力相互作用体系和刚性地基上高层建筑结构的振动台模型试验成果的对比分析，研究了相互作用对结构动力特性和地震反应的影响。结果－地基动力相互作用使结构频率减小，阻尼增大；相互作用体系的振型曲线与刚性地基上结构的振型曲线不同，基础处存在平动和转动；在地震动作用下考虑相互作用的结构加速度、层间剪力、弯矩以及应变通常比刚性地基上的情况小，而位移则比刚性地基上的情况大。     

土-结构相互作用效应对结构基底地震动影响的试验研究

利用土与结构动力相互作用振动台模型试验数据,通过各种试验工况下土层表面与基础表面加速度反应的比较,深入探讨了土与结构动力相互作用效应对高层建筑结构基底地震动的影响。从输入地震动频谱特性、输入地震动强度水平和上部结构动力特性3个方面详细分析了与SSI效应对高层建筑基底震动影响程度有关的一些因素。结果表明：SSI效应对高层建筑基底地震动的影响与输入地震波的动力特性有很大关系。在地震动的频谱成分方面,SSI效应对高层建筑基底地震动的影响主要体现为土层表面和基础表面在与输入地震动卓越频率相近处的频谱成分有较大差异;SSI效应对高层建筑基底地震动的影响程度随着输入加速度峰值水平的增加而减小;在某一特定地震波作用下,当上部结构的振动频率与地震地面运动的卓越频率相近时,SSI效应对高层建筑基底地震动的影响较为强烈。     

Study on soil-pile-structure-TMD interaction system by shaking table model test

The success of the tuned mass damper (TMD) in reducing wind-induced structural vibrations has been well established. However, from most of the recent numerical studies, it appears that for a structure situated on very soft soil, soilstructure interaction (SSI) could render a damper on the structure totally ineffective. In order to experimentally verify theSSI effect on the seismic performance ofTMD, a series of shaking table model tests have been conducted and the results are presented in this paper. It has been shown that the TMD is not as effective in controlling the seismic responses of structures built on soft soil sites due to the SSI effect. Some test results also show that a TMD device might have a negative impact if the SSI effect is neglected and the structure is built on a soft soil site. For structures constructed on a soil foundation, this research verifies that the SSI effect must be carefully understood before a TMD control system is designed to determine if the control is necessary and if the SSI effect must be considered when choosing the optimal parameters of the TMD device.     

分层土-基础-高层框架结构相互作用体系振动台模型试验研究

本文设计实现了分层土－基础－高层框架结构相互作用体系的振动台模型试验，再现了地震动激励下上部结构和基础的震害现象和砂质粉土的液化现象。通过试验，研究了相互作用体系地震动反应的主要规律：由于动力相互作用的影响，软土地基中相互作用体系的频率小于不考虑结构－地基相互作用的结构频率，而阻尼比则大于结构材料阻尼比；体系的振型曲线与刚性地基上结构的振型曲线明显不同，基础处存在平动和转动。土层传递振动的放大或减振作用与土层性质、激励大小等因素有关，砂土层一般起放大作用，砂质粉土层一般起减振隔振作用；由于土体的隔震作用，上部结构接受的振动能量较小，各层反应均较小。上部结构顶层加速度反应组成取决于基础转动刚度、平动刚度和上部结构刚度的相对大小。     

软土地基核电厂房动力响应振动台试验

为了分析软土地基－筏基础核电厂房结构地震反应规律和特征,利用地震模拟振动台开展了软土地基－筏基础－核电厂房动力相互作用问题的试验研究。分别进行了表面水平土体模型和表面凹陷土体模型的运动相互作用试验、地基土－筏基础－核电厂房振动台相互作用试验、核电厂房直接固定在振动台面上的刚性基底振动台试验。试验采用圆形叠层剪切模型箱,地基土模型为某工程场地的均匀粉质粘土,其剪切波速为213 m/s;核电厂房简化为3层框架剪力墙结构模型。试验输入波形为美国核电规范常用的RG1.60反应谱合成得到的人工地震动时程。振动台试验结果对比分析表明:土－结构体系中系统的振动周期和阻尼明显大于刚性基底下结构的振动周期和阻尼;相同地震作用下在土－结构动力相互作用体系中结构加速度明显小于刚性基底下的结构加速度反应;而位移明显大于刚性基底下结构的位移。本文的研究成果可为软土地基建立核岛厂房的适应研究提供参考。     

A substructure method for earthquake analysis of structures including structure-soil interaction

A general substructure method for analysis of response of structures to earthquake ground motion, including the effects of structure-soil interaction, is presented. The method is applicable to complex structures idealized as finite element systems and the soil region treated as either a continuum, for example as a viscoelastic halfspace, or idealized as a finite element system. The halfspace idealization permits reliable analysis for sites where essentially similar soils extend to large depths and there is no rigid boundary such as soil-rock interface. For sites where layers of soft soil are underlain by rock at shallow depth, finite element idealization of the soil region is appropriate; in this case, the direct and substructure methods would lead to equivalent results but the latter provides the better alternative. Treating the free field motion directly as the earthquake input in the substructure method eliminates the deconvolution calculations and the related assumption—regarding type and direction of earthquake waves—required in the direct method. Spatial variations in the input motion along the structure-soil interface of embedded structures or along the base of long surface supported structures are included in the formulation. The substructure method is computationally efficient because the two substructures—the structure and the soil region—are analysed separately; and, more important, it permits taking advantage of the important feature that response to earthquake ground motion is essentially contained in the lower few natural modes of vibration of the structure on fixed base.     

考虑地基土液化影响的桩基高层建筑体系地震反应分析

本文建立了土体－结构体系地震反应分析的混合有限元法，并研究了地基土液化对地震反应的影响。本方法把土体－结构体系简化为一个完整的体系，该体系由梁（柱）单元、剪切杆单元、刚体单元、平面四边形等参单元与三角形单元、界面单元的任意组合来模拟。桩与上部结构材料视为线弹性体，土介质视为非线性材料。土的静应力－应变关系之间的非线性用邓肯一张模型来描述；土的动应力－应变关系之间的非线性和振动孔隙水压力对土的软化效     

Case study of strong ground motion variations across cut slope

We evaluate the influence of topography on motions recorded at the base and crest of an approximate 3H:1V, 20 m single-faced slope. The motions were recorded during the 1983 Coalinga earthquake mainshock and two aftershocks. Mainshock peak accelerations at the crest and base transverse to the slope face were 0.59 and 0.38 g, respectively. The spectral amplification of crest motion occurred across T≈0–2 s. Differences between the crest/base motions are postulated to result principally from soil-structure interaction (base instrument is in a structure), variations in local ground response, and topography. Transfer functions quantifying soil-structure interaction (SSI) effects are evaluated and the base motion is modified at short periods to correct it to an equivalent free-field motion. The different levels of ground response at the crest and base are identified based on location-specific measurements of soil shear wave velocities. Differences between crest/base motions not accounted for by SSI or differential ground response are attributed to topographic effects. By these means, topographic spectral amplification (i.e. amplification relative to level ground conditions) is estimated to be about 1.2 at the crest and about 0.85–0.9 at the base across the period range T≈0.4–1.0 s.     

Seismic response and damage analysis of buildings supported on flexible soils

The investigation reported in this paper studies the effects of soil–structure interaction (SSI) on the seismic response and damage of building–foundation systems. A simple structural model is used for conducting a parametric study using a typical record obtained in the soft soil area of Mexico City during the 1985 earthquake. Peak response parameters chosen for this study were the roof displacement relative to the base and the hysteretic energy dissipated by the simple structural model. A damage parameter is also evaluated for investigating the SSI effects on the seismic damage of buildings. The results indicate that in most cases of inelastic response, SSI effects can be evaluated considering the rigid‐base case and the SSI period. Copyright © 2000 John Wiley & Sons, Ltd.     

Equivalent linearization of non-linear soil-structure systems

The concept of equivalent linearization, in which the actual nonlinear structure is replaced by an equivalent linear single-degree-of-freedom (SDOF) system, is extended for soil-structure systems in order to consider the simultaneous effects of soil-structure interaction (SSI) and inelastic behavior of the structure on equivalent linear parameters (ELP). This is carried out by searching over a two-dimensional equivalent period–equivalent damping space for the best pair, which can predict the earthquake response of the inelastic soil-structure system with sufficient accuracy. The super-structure is modeled as an elasto-plastic SDOF system whereas the soil beneath the structure is considered as a homogeneous half-space and is replaced by a discrete model. An extensive parametric study is carried out for a wide range of soil-structure systems subjected to a suite of 59 ground motions. The effect of SSI on ELP is studied through introducing a set of non-dimensional key parameters, which define the soil-structure system. It is shown that ELP of soil-structure systems result from a trade-off between SSI effect and nonlinear behavior of the structure. The contribution of each of these two factors depends on the characteristics of the soil-structure system which, in turn, are defined by the introduced non-dimensional key parameters. Moreover, the reliability of the predicted response of soil-structure systems and its sensitivity to deviation from optimal ELP is studied in detail, which sheds light on the consequences of using improper pairs of ELP for interacting systems in the framework of performance-based design of structures. Copyright © 2012 John Wiley & Sons, Ltd.