【作者】 刘小伟；

【导师】 狄生奎；

【作者基本信息】 兰州理工大学 ， 桥梁与隧道工程， 2012， 硕士

【摘要】 本文首先介绍了有关抗震分析的三种计算方法：反应谱法、时程分析法、随机振动法。然后为了研究和介绍大跨度桥梁的多点激励分析问题，基于时程分析理论，应用直接加速度法和大质量法，通过对两种简化模型的分析，探讨了空间变化效应对结构地震响应结果的影响；研究了激励输入模式、不同地震波、波速、几何非线性、波的输入方向等因素对地震响应的影响规律；基于大质量法的计算原理，在Midas/Civil有限元软件平台上实现了多点激励下大跨度桥梁的地震反应分析。讨论了行波效应和多点激励在结构抗震分析中的输入模式，主要探讨了大质量法的应用问题。分析结果表明：在地震激励下，边跨的关键点也可能成为大跨连续拱桥的控制点，在工程设计中应该引起重视。在不同地震激励模式作用下地震响应差别很大，尤其是行波效应可以改善固定墩受力，因此考虑三维地震、行波激励和多点激励更为合理。深入研究桥梁抗震性能对确保桥梁安全性尤为重要，本文以3跨连续下承式钢管混凝土系杆拱桥为工程背景，以大型有限元分析软件Midas/Civil为平台，对该桥进行地震反应分析。主要研究内容包括：1.采用有限元分析软件Midas/Civil，通过适当简化建立了拱桥的结构模型，作为进行动力分析的基础，分析了拱桥的自振特性。2.建立相应动力学方程来描述大跨度拱桥的动力性能，并选用适当的求解方法对问题进行求解。3.选用经过幅值调整的天津波、Taft波和EI-Centro地震波三种加速度时程曲线，对拱桥空间有限元模型进行考虑几何非线性的一致激励、行波激励下的地震时程响应分析。4.分别沿模型的纵向、纵向加横向及三维方向输入修正后的加速度曲线，进行了地震时程响应分析，得到了有限元模型对应控制截面的应力和位移响应。5.考虑非一致激励行波效应，进行一致激励和非一致激励地震动加速度时程输入，对不同波速激励下地震时程反应进行对比分析，探讨了地震动空间变异性对大跨桥梁在地震作用下反应的影响。6．采用反映地震动空间和时间变异性的人工地震波，对大跨拱桥空间有限元模型进行在一致激励、行波激励和多点激励下的地震时程反应分析，并比较了不同地震激励下时程分析结果，主要探讨了大质量法的应用问题。更多还原

【Abstract】 Three methods of the seismic analysis, the response spectrum method, the time history method and the random vibration method, were introduced firstly. Based on the time history analysis theory, the direct acceleration method and the large-mass method were extended to make investigation to the multi-supported seismic analysis of long-span bridges.Two simplified models were extensively investigated to examine the spatial effects on the structural seismic responses. The effects of the primary factors such as excitation pattern, seismic waves, wave velocity, geonomic nonlinear and spreading direction of the earthquake wave and so on have been investigated. Based on the large-mass method, the seismic responses analysis of long-span bridges under multi-support excitation were realised on the platform of commercial finite element program Midas/Civil.The input mode of structure seismic analysis under traveling wave effect and multi-support excitations was discussed, and the application of the input of the large mass method was mainly researched.The calculated results reveal that the key points of side arch also may be the reference points of the long multi-span arch bridge under action of seismic excitation, which should be considered in engineering design. The seismic responses of the bridge varies greatly with different excitation patterns of earthquakes, especially traveling wave effect can improve fixed pier, so three-dimensional seismic wave, the travelling wave excitation and the multi-support excitation should be considered.It is necessary to make an indepth study and analysis to the seismic performance of these bridges, which is an important factor for safety.In this thesis, choosing a3-span continuous through concrete-filled steel tubular(CFST) tied-arch bridge as project background, carry out the seismic response with the finite element analysis software Midas/Civil.The study includs the following aspects:1.The finite element model of the structure was built through reasonable simplification, and vibration mode were studied by using the famous program of Midas/Civil.2.The corresponding dynamics equations were established to describe the bridge’s dynamic actions while appropriate method was chosen to solve these equations. 3. Three acceleration time-history curves whose amplitudes have been adjusted including Tianjin wave, Taft wave and El-Centro wave were chosen to analyze seismic time-history response under the uniform excitation, the travelling wave excitation considering geometric nolinear by using three-dimension finite element model.4.Inputing the modified acceleration time-history curve along longitudinal direction, longitudinal and transverse direction and3D direction, the internal force and displacement of the control sections are gained.5. Taking non-consistent excitation travelling wave effeet into account, the consistent excitation and non-consistent excitation earthquake time-history acceleration were inputted, and the seismic reactions of the bridge under the different wave velocity were compared to explore the impact of the spatial variability of earthquake ground motions in large-span bridges.6.The artificial waves involved in spatial and temporal variability were used to analyze seismic time-history response under the uniform excitation, the travelling wave excitation and multi-support excitation comparing results of different patterns of earthquake excitations by using three-dimension finite element model and the application of large mass method was mainly researched.更多还原