本文選題：土－結構相互作用 + 有限元方法��； 參考：《天津大學》2013年博士論文

【摘要】：近年來隨著施工技術的進步，新型建筑材料的出現(xiàn)，以及機械及計算機技術在建筑行業(yè)的廣泛應用，高層建筑的發(fā)展具備了良好的物質基礎和建設條件，建筑規(guī)模和建筑高度一直在不斷增加。在建筑結構的設計中，結構抗震分析是一個重要的課題。然而將結構與基礎分別獨立設計的剛性基礎假設方法，已經(jīng)不能滿足實際工程需要，隨著現(xiàn)代抗震設計理論的逐步完善，地基土－高層結構動力相互作用的分析方法越來越多的應用到工程抗震分析中。在土－結構相互作用問題的研究中，地基的特性、結構的平面尺寸以及結構的基礎埋深等，都對建筑地震反應有著不同程度的影響，可以通過對比分析，找出每種考慮因素對地震反應分析的影響規(guī)律，進一步完善土－結構相互作用理論成果。針對這一課題，論文運用數(shù)值方法進行了一系列的分析，主要的創(chuàng)新工作與成果有： （1）基于有限元分析方法建立了土－結構相互作用計算模型，選取15層框架結構為計算算例，設定三種不同底面積但周期相近的框架結構，進行地震反應時程分析，為了在三維模型中提高計算效率，使用超單元方法以節(jié)省計算時間。通過二維模型和三維彈塑性帶樁基模型計算，取得了較為一致的結論，結果表明：由于結構的自振周期與結構的剛度和質量有關，當結構跨度、梁柱尺寸及單位質量相同時，不同底面積結構的自振周期基本相近；考慮相互作用之后，結構自振周期明顯增大，此時體系的地震反應不僅與體系本身性質有關，還與土體對結構的約束力大小密切相關。 （2）考慮土體與結構相互作用后，在同一種地震波作用下，結構頂層總位移較剛性基礎頂層位移有所增大，且隨著結構底面積的增大而減小，由基礎轉動引起的位移隨著結構底面積的增大而明顯減小，上部結構自身位移，在總位移中所占比例以及平均基底剪力隨著底面積的增加而增大。三種不同底面積相互作用體系上部結構的層間位移曲線則有較大差別，上部結構的層間位移峰值小于剛性基礎結構的層間位移峰值。土體剛度越大，相互作用影響效果越小，上部結構頂層的位移反應峰值也越小，結構的轉動位移和平動位移數(shù)值減小。比較不同特性的地震波，不同底面積結構頂層總位移、基礎轉動、基礎平動、結構自身位移和內力的變化規(guī)律趨勢相同。 （3）同一種平面尺寸，結構頂層總位移隨著基礎埋深的增大而減小，上部結構位移在總位移中所占比例以及平均基底剪力均隨著基礎埋深的增加而增大。與增加底面積的模型相比較，增加結構基礎埋深，對減小結構頂層總位移，，特別是減小基礎轉動的效果更為顯著。在不同的地震波作用下，考慮相互作用之后，不同埋置深度結構的最大層間位移變化曲線形狀基本一致。層間位移峰值均發(fā)生在結構第三、四層附近，且基礎埋深最大的結構層間位移峰值最大，但均小于剛性基礎時的最大層間位移角值。 （4）為了進一步考察在一般情況下改變底面積對土－結構相互作用地震反應的影響，基于抗震設計中反應譜理論，探討底面積對土－結構相互作用地震反應譜的影響。針對不同場地條件選取一定數(shù)量的地震波，建立土－結構整體彈性體系三維數(shù)值分析模型進行動力分析，求得上部結構與土體之間交界面上的耦合作用，將此耦合作用與原地震波疊加后，得到上部結構實際受到的考慮了相互作用之后的地震波作用，即為修正地震波，并繪出此修正地震波的反應譜曲線并求得平均值。對影響修正地震波反應譜曲線變化的各種因素進行定性的分析，得出一些規(guī)律性結論：由于原地震波特性不同，場地土對原地震波的吸收與放大程度均不相同，但所得修正地震波加速度峰值均有不同程度的減小，且修正地震波平均反應譜曲線峰值也較原地震波減��；結構底面積越大，結構受到土體的約束力越大，修正地震波反應譜曲線峰值越�。煌坏酌娣e結構，土體越軟，土－結構相互作用效果越顯著，修正地震波反應譜曲線的峰值越小。
[Abstract]:In recent years, with the progress of construction technology, the emergence of new building materials, and the extensive application of mechanical and computer technology in the construction industry, the development of high building has a good material base and construction conditions. The scale and height of the building have been increasing continuously. In the design of the building structure, the seismic analysis of the structure is a However, the rigid foundation hypothesis method, which separately designs the structure and foundation separately, is unable to meet the actual engineering needs. With the gradual improvement of the modern seismic design theory, the analysis method of the dynamic interaction of the foundation soil and the high-rise structure is more and more applied to the seismic analysis of the engineering. The soil structure interaction is used. In the study of the problem, the characteristics of the foundation, the plane size of the structure and the foundation depth of the structure have different influence on the seismic response of the building. Through the comparative analysis, we can find out the influence laws of each factor on the seismic response analysis, and further improve the theoretical results of the soil structure interaction. A series of analyses have been carried out by using numerical methods. The main innovations and achievements are as follows:
(1) a calculation model of soil structure interaction is set up based on the finite element method. The 15 story frame structure is selected as the calculation example, and three kinds of frame structures with different bottom area but similar period are set, and the seismic response time history analysis is carried out. In order to improve the calculation efficiency in the three-dimensional model, the superelement method is used to save the calculation time. Through two, the calculation time is saved. The dimensional model and the three-dimensional elastoplastic belt pile foundation model are calculated. The results show that the vibration period of the structure is related to the stiffness and the mass of the structure. When the structure span, the beam column size and the unit mass are the same, the self vibration period of the different bottom area structure is almost similar. After considering the interaction, the structure is self excited. The cycle is obviously increased, and the seismic response of the system is not only related to the nature of the system itself, but also closely related to the binding force of the soil on the structure.
(2) under the interaction of soil and structure, under the action of the same seismic wave, the total displacement of the top layer of the structure is larger than that of the rigid base, and decreases with the increase of the bottom area of the structure. The displacement caused by the rotation of the foundation decreases with the increase of the base area of the structure, and the displacement of the superstructure is accounted for in the total displacement. The ratio and the average base shear increase with the increase of the bottom area. The interlayer displacement curves of the upper structure of the three different floor area interaction systems are different. The peak interlayer displacement of the superstructure is smaller than the peak displacement peak of the rigid base structure. The greater the soil stiffness, the smaller the effect of interaction, the top structure top. The displacement response peak of the layer is also smaller, the rotational displacement and the translational displacement of the structure decrease, and the different characteristics of the seismic waves, the total displacement of the top floor of different bottom area structure, the foundation rotation, the basic translational movement, the change of the structural self displacement and internal force are the same.
(3) in the same plane size, the total displacement of the top layer decreases with the increase of the foundation depth, the proportion of the displacement of the superstructure in the total displacement and the average base shear increase with the increase of the foundation buried depth. The effect of small foundation rotation is more remarkable. Under the action of different seismic waves, the maximum interlayer displacement curve shape of different buried depth structure is basically the same after considering the interaction. The peak value of interlayer displacement occurs near the third, fourth layer of structure, and the maximum interlayer displacement peak of the most basic buried depth is maximum, but all less than the rigidity. The maximum interlayer displacement angle of the base.
(4) in order to further investigate the influence of the bottom area on the seismic response of soil structure interaction in general conditions, based on the response spectrum theory in the seismic design, the effect of the bottom area on the seismic response spectrum of soil structure interaction is discussed. A certain number of seismic waves are selected for different site conditions, and the earth structure integral elastomer is established. A three-dimensional numerical analysis model is used to analyze the coupling effect on the interface between the superstructure and the soil. After the coupling action is superposed with the original seismic wave, the superstructure is actually subjected to the interaction of seismic waves, that is, to modify the seismic wave and to draw the response spectrum curve of the modified seismic wave. According to the qualitative analysis of various factors affecting the variation of the response spectrum curve of the seismic wave, some regular conclusions are obtained: the original seismic wave absorption and magnification degree are different because of the different characteristics of the original seismic waves, but the corrected seismic wave addition velocity peaks are reduced in varying degrees and modified. The peak of seismic wave average response spectrum curve is also smaller than that of the original seismic wave. The larger the structure bottom area is, the larger the structure is, the greater the binding force of the soil, the smaller the peak of the response spectrum curve of the corrected seismic wave. The more soft the soil body is, the more significant the soil structure interaction effect is, the smaller the peak of the correction of the response spectrum curve of the seismic wave.
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TU435;TU973.31

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