【作者】 刘文华；

【导师】 杨庆山；

【作者基本信息】 北京交通大学 ， 结构工程， 2007， 博士

【摘要】 地震地面运动是一复杂的时间-空间过程，同一次地震中结构尺度范围内不同点的地震动过程是不同的，这是因为地震波在传播过程中具有行波效应、相干效应和场地效应等。严格来说所有结构的地震反应分析均应考虑地震动空间变异性的影响。但当结构尺度较小或采用整体基础时，这种影响可能较小，常可按一致激励进行分析；随着结构尺度的不断扩大(大跨空间结构)和延长型结构(长大桥梁、管线)的兴建，地震动空间变异性的影响越来越显著。研究表明大跨度结构在抗震设计中应考虑多点激励的影响。另外，就结构本身而言，截面形式多样，尺度相差大，节点形式复杂的复杂结构也将逐步得到应用。本文将围绕这一课题，进行大跨复杂空间结构在多点地震动激励下的非线性反应分析，主要内容包括以下几个方面：1、非平稳地震动场的人工合成。对大跨空间结构进行多点激励动力分析时，需要一组具有空间相关性的地震波。然而，由于工程场址各不相同，已观测得到的地震动场一般不能符合拟建场地的要求，因此，需要模拟符合特定场地条件和空间相关性要求的非平稳地震动场。本文利用了功率谱、相位谱和幅值谱之间的关系及相位差谱影响地震动非平稳性的特性，用相位差谱的统计模型生成相位谱，用功率谱统计模型和规范反应谱生成幅值谱，用相干函数统计模型考虑相干性，最后人工合成了地震动场，生成的地震动场具有时频非平稳性，适用于规范规定的各类场地类型，可以考虑地震波传播时的行波效应、相干效应和场地效应。2、结构在多点地震动激励作用下的时程反应分析模型。在分析多点地震动激励下的结构反应时不同文献中曾使用过多种不同的模型，但均未明确讨论过各自的理论基础和应用条件。本文从支座移动时的结构静力平衡方程出发，根据地震动时程输入方式的不同和结构在支座移动随时间变化时的动力平衡方程，总结并推导了多点激励作用下结构地震反应时程分析的四种模型，并以一平面刚架结构为例分析了其理论基础和选择模型的原则。3、大跨结构在多点地震动激励作用下的反应分析。地震动传播时具有的行波效应、场地效应、不相干效应和衰减效应，都能对结构的反应产生影响，其中衰减效应对相干函数影响很小，可以忽略。本文以四个大跨度结构为例按照不同的工况对地震动传播效应对结构反应的影响进行了研究。研究内容包括单种效应，即行波效应、场地效应、不相干效应对结构反应的影响；两种及三种效应组合，即行波效应和场地效应、行波效应和不相干效应、场地效应和不相干效应、行波效应场地效应和不相干效应对结构反应的影响。4、国家体育场线性时程反应分析。本文采用基于相位差谱非平稳地震动场的人工合成方法生成了国家体育场的多点地震动激励非平稳地震动场，进行了国家体育场在多点地震动激励作用下的地震反应分析，分别分析结构在X、Y和Z三个方向多点地震动激励和一致地震动激励作用下柱顶、内环梁的最大位移反应和基底反力，将计算结果与一致激励的进行了对比，得出了可供工程设计参考的结论。5、子结构技术在复杂大跨结构地震反应分析中的应用。为了解决复杂结构自由度数目庞大，计算效率低的问题，本文将近年来发展的子结构技术应用到大跨度复杂结构的非线性分析中。在介绍子结构技术的基本理论、子结构划分和子结构应用的基础上，以一空间两层刚架为例介绍了子结构技术在工程抗震非线性分析中的应用过程并验证了计算结果的精度。6、国家体育场非线性时程反应分析。在强震作用下，结构会由线性进入非线性。本文将子结构技术应用到国家体育场这一复杂大跨结构的非线性时程分析中，介绍了子结构技术在国家体育场时程分析中的应用，并验证了其动力特性和计算精度，在此基础上对国家体育场结构进行了非线性时程分析，利用人工合成的国家体育场罕遇地震非平稳地震动场，分别研究了国家体育场在一致地震动激励作用下的非线性时程反应和多点地震动激励作用下的非线性时程反应。更多还原

【Abstract】 The ground motion is a complicated time-space process. There are some characters about the seismic in the process of propagation, such as incoherence effect, wave-passage effect, site-response effect and attenuation affect etc. It has been verified that the ground motions inputting at different supports of large-span structures are different, which may be modeled by phase shifts and coherency losses. The phase shifts are caused by waves propagating, while the coherency losses can be attributed to many factors such as source mechanism, path and local site effects, etc. Significant contributions on these issues have been made, and studies on response of large span structures have shown that the effects of multi-support excitations must be considered. This thesis will work in the nonlinear response analysis of large-span complex structure under specially varying earthquake ground motions, and the main contents are as following.1. Generation of ground motion fieldIn the response analysis of large-span structures under specially varying earthquake ground motions, series of seismic waves are needed. Although there have been many recordings about seismic, but the sites about the structures are different, and the present seismic recordings are not satisfying the needing of structures analysis. So, response analysis of structure under seismic need generate artificial ground motions. In this thesis, based on the controlling influence of phase-difference spectrum on the non-stationafity of ground motions, and the relationships of the phase spectrum, power density spectrum and flourier amplitude spectrum, the ground motion field is generated. The statistic model of phase-difference generates the phase-difference spectrum, the statistic model of power spectrum generates the power spectrum, and the statistic model of the coherence function considers the coherence character. The generated ground motion field can consider the influences of incoherency effect, wave-passage effect, and local site effect.2. Time-history analysis models of structure under multi-support earthquake excitationsThere are some models in structure analysis under seismic excitations, and it is very difficult to select a rational model used in the time-history analysis. In this thesis, the analysis models of structure under multi-support seismic excitations are studied. When the earthquake occurred, the ground motion inputs at multiple supports of structures are different. Base on the static equilibrium equation of supports offset, the dynamic equilibrium equation of structure under time-varying base movement is derived, and four different analysis models are presented. A frame structure under seismic excitation is studied using these four models.3. Response analysis of large-span structures under multi-support excitationsThe responses of structure under multi-support excitations are influenced by (1) incoherency effect, (2) wave-passage effect, (3) site-response effect, and (4) attenuation effect. It is found that the influence of attenuation effect is small, and can be ignored. In the thesis, the influences of the three effects to structure response under multi-supports excitations are studied. It is including the influence study of single effect, namely as wave passage effect, spatial incoherent effect and site-response effect, and the influence study of two effects assembly and three effects assembly.4. Linear response analysis of national stadium under specially varying earthquake ground motionsThe time history analysis method is applied to analyze the National Stadium. Spatially varying ground motion time histories are simulated for the analysis. The responses of uniform support excitation and multiple support excitations of the National Stadium are studied, in which the spatially varying excitations and uniform excitation in two horizontal and vertical directions are considered.5. Application of substructure for large-span complex structure under multi-supports excitationsSubstructure method is an advanced analytical technique of FEM, and it is of great value and prospects for engineering. The aims for using substructure is to save computing time and to solve super scale problems under limited computing resource. In this thesis, the using of substructure in large-span complex structure for dynamic nonlinear analysis is studied. The fundamental equation is presented and the application process of substructure method is also discussed, A two-floor spatial frame is studied by the substructure method. It proves that the Substructure method is valid and feasible in dynamic analysis.6. Nonlinear response analysis of national stadium under specially varying earthquake ground motionsUnder the strong earthquake, the structure may be into nonlinear, including geometric nonlinearity and material nonlinearity. The nonlinear responses of uniform support excitation and multiple support excitations of the National Stadium are studied, in which the spatially varying excitations and uniform excitation in two horizontal and vertical directions are also considered.更多还原