单层球壳多点输入振动台倒塌试验研究

发布时间：2018-03-05 22:02

本文选题：单层球壳　切入点：多点输入时程分析　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：作为大跨度空间结构的一个重要分支,网壳结构是目前大跨度空间结构中应用最广泛的结构类型。鉴于我国地处地震灾害严重的区域,学者们对以网壳结构为代表的大跨度空间结构在地震作用下的倒塌失效机理进行了系统的研究工作。与理论相比,从试验角度去验证和探索网壳结构强震失效机理的工作相对较少。因此,本课题通过对多点输入下单层球壳振动台倒塌试验的研究,从试验角度观察了地震作用下单层球壳的动力响应,并运用有限元软件模拟了结构在强震作用下的倒塌破坏过程。本文的主要内容和结论如下：(1)根据相似比理论及原型的拓扑关系严格设计2个单层球壳缩尺模型,不做任何简化。两个模型的跨度为23.4m,矢高为11.7m。模型1正常设计,除了底部一圈加强之外,其余部分刚度均匀；模型2在模型1设计的基础上人为设置了两个薄弱区,期待其在相同的地震激励下发生与模型1不同的动力响应。通过逐级提高输入地震波的加速度峰值,观测每个工况下模型的反应特征,完成单层球壳振动台倒塌试验。从试验结果来看,由于特殊的边界条件,两个模型都发生突然的倒塌破坏。倒塌前,模型1塑性区域不断发展,杆件截面塑性开展充分。而模型2由于人为设置了薄弱区,该区域的杆件最先失效,倒塌时该区域破坏严重。因此,在实际中进行结构设计时,应避免出现刚度不均匀。(2)根据设定的目标自功率谱密度函数和互功率谱密度函数模拟生成四条相干地震波,并对生成的地震波进行频谱分析,验证其合理性,以用于后期的数值模拟分析以及振动台试验的加载输入。在ANSYS中采用大质量法实现模型多点输入时程分析,获得结构的动力响应。模拟时考虑了几何非线性和材料非线性。模拟时发现,大质量取为结构总质量的104-108倍时,可保证结构多点输入地震分析的准确性。(3)在倒塌工况下,利用生死单元技术模拟结构在加载过程中因杆件失效退出工作而造成的结构形式和边界条件的变化,展现了结构从弹性进入塑性以及塑性开展直至结构倒塌的全过程。最终将倒塌模式与试验结果进行对比分析,验证了试验方案和数值计算模型的合理性。
[Abstract]:As an important branch of long-span spatial structure, latticed shell structure is the most widely used structural type in long-span spatial structure at present. Scholars have systematically studied the collapse failure mechanism of long-span space structures, represented by latticed shell structures under earthquake. There is relatively little work to verify and explore the failure mechanism of reticulated shell structures from the point of view of test. Therefore, in this paper, the collapse test of single-layer spherical shell vibration table with multi-point input is studied. The dynamic response of a single-layer spherical shell subjected to earthquake is observed from an experimental point of view. The collapse and failure process of the structure subjected to strong earthquakes is simulated by using finite element software. The main contents and conclusions of this paper are as follows: (1) according to the similarity ratio theory and the topological relation of the prototype, two single-layer spherical shell scale models are strictly designed. There is no simplification. The span of the two models is 23.4m and the vector height is 11.7m.Model 1 is normally designed, and the stiffness of the rest of the model is uniform except for the one ring at the bottom. Model 2 has two weak areas artificially set up on the basis of the design of model 1. By increasing the acceleration peak of the input seismic wave step by step, the response characteristics of the model under each working condition are observed, and the dynamic response of the model is expected to be different from that of model 1 under the same earthquake excitation. The collapse test of single layer spherical shell vibration table was completed. According to the test results, both models collapsed suddenly because of special boundary conditions. Before the collapse, the plastic region of model 1 developed continuously. The plasticity of the section of the member is fully developed. Model 2, because of the artificial weak zone, the member in the region is the first to fail, and the area is damaged seriously when it collapses. Therefore, when the structural design is carried out in practice, Four coherent seismic waves should be generated according to the target self-power spectral density function and cross-power spectral density function, and the frequency spectrum analysis of the generated seismic waves is carried out to verify its reasonableness. It is used for the later numerical simulation analysis and the loading input of the shaking table test. The large mass method is used to realize the model multi-point input time history analysis in ANSYS. The dynamic response of the structure is obtained. Geometric nonlinearity and material nonlinearity are taken into account in the simulation. It is found that when the mass is 104-108 times of the total mass of the structure, the accuracy of the multi-input seismic analysis of the structure can be ensured under the collapse condition. The life and death element technique is used to simulate the change of structure form and boundary conditions caused by the failure and exit of the member during the loading process. The whole process from elasticity to plasticity and plastic development to collapse of the structure is shown. Finally, the rationality of the test scheme and the numerical calculation model is verified by comparing the collapse mode with the experimental results.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU317;TU399

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