考虑随机初始缺陷的钢框架—支撑结构试验研究与有限元分析

发布时间：2018-08-27 14:34

【摘要】：相比传统的计算长度系数设计法,高等分析与设计方法因其准确、快速和实用等优势广泛应用在多高层钢框架结构的受力分析和设计上。目前国内外关于高等分析方法的研究热点普遍集中在如何精确考虑非线性因素影响下结构的极限承载能力,对此阶段结构的变形性能研究尚少。但有研究表明,按照承载力极限状态设计框架时,高柔的钢框架整体侧移往往超出结构正常使用极限状态的标准,实际承载力是由结构的变形性能控制的。结构的变形性能受各种非线性因素影响,特别是结构和构件的初始几何缺陷影响尤为突出,而现阶段各个国家和地区规范关于考虑初始几何缺陷的大小、方向和分布形式都没有明确统一的规定,致使按照规范要求偏向一侧布置缺陷的多高层框架初始侧移很可能不满足结构整体垂直度的要求,且与结构构件真实缺陷的大小和方向呈随机性分布情况不符。针对上述两个主要问题,本文主要展开了如下工作：对六层框架-支撑结构分别采用一阶弹性分析、近似二阶弹性分析以及高等分析方法进行设计,对比采用不同设计方法时结构的极限承载力、构件内力和最终变形情况,分析表明了结构高等设计方法的优越性及现阶段计算方法的不足。对两榀单跨双层纯钢框架和框架支撑结构进行了缩尺试验,重点研究了初始几何缺陷对结构变形性能的影响。将试验前测得的框架梁柱的初始几何缺陷分布反馈到自编的考虑随机初始缺陷的有限元模型中,由试验结果与有限元分析结果对比吻合较好,证明了考虑随机初始缺陷有限元模型的正确性。采用有限元软件分别对六层、十二层、二十层以及三十层钢框架-支撑结构的随机缺陷模型进行全过程高等分析,采用蒙特卡罗法拉丁超立方抽样的技术模拟了框架随机初始缺陷的分布情况,并对比多种国内外规范考虑初始缺陷的方法,重点研究了结构和构件的变形性能。研究和分析结果表明,框架-支撑结构的变形性能与初始几何缺陷的大小成正比；考虑随机初始几何缺陷的支撑框架变形与无缺陷理想框架的柱顶侧移相差不大,在高柔结构的高等分析中可不考虑。对高柔的框架支撑结构进行高等分析与设计,所计算的极限承载力通常因此阶段框架变形超出正常使用极限要求而失效,结构设计最终由变形性能来控制,由此提出一种适用于高柔钢框架-支撑结构,基于变形性能的实用高等设计方法。
[Abstract]:Compared with the traditional design method of calculating length coefficient, the advanced analysis and design method is widely used in the analysis and design of multi-high-rise steel frame structure due to its advantages of accuracy, rapidity and practicality. At present, the research focus of advanced analytical methods at home and abroad is generally focused on how to accurately consider the ultimate bearing capacity of structures under the influence of nonlinear factors, but there is little research on the deformation behavior of structures at this stage. However, some studies show that when the frame is designed according to the ultimate state of bearing capacity, the overall lateral displacement of the steel frame is often beyond the standard of the limit state of normal use of the structure, and the actual bearing capacity is controlled by the deformation performance of the structure. The deformation performance of structures is affected by various nonlinear factors, especially the initial geometric defects of structures and members. Neither the direction nor the distribution form is clearly and uniformly defined, resulting in the initial lateral displacement of multi-high-rise frames with defects on one side of the code being biased against the requirements of the overall perpendicularity of the structure. And it is not consistent with the random distribution of the size and direction of the real defects of the structural members. In view of the above two main problems, the main work of this paper is as follows: the first order elastic analysis, the approximate second order elastic analysis and the advanced analysis method are used to design the six-story frame-braced structure. By comparing the ultimate bearing capacity, internal force and final deformation of the structure with different design methods, the advantages of the advanced structural design method and the shortcomings of the present calculation method are analyzed. In this paper, two single-span and double-layer steel frames and frame braced structures are tested by scale test, and the effect of initial geometric defects on the deformation properties of the structures is studied. The initial geometric defect distribution of the frame Liang Zhu measured before the test is fed back to the self-compiled finite element model with random initial defects. The comparison between the experimental results and the finite element analysis results is in good agreement. It is proved that the finite element model considering random initial defects is correct. The stochastic defect models of six, twelve, twenty and thirty story steel frame-braced structures are analyzed by finite element software. Monte Carlo Latin hypercube sampling is used to simulate the distribution of random initial defects in frames. The deformation properties of structures and members are studied by comparing various methods of considering initial defects in codes at home and abroad. The results of study and analysis show that the deformation performance of frame-braced structure is proportional to the size of initial geometric defect, and the deformation of braced frame with random initial geometric defect is not different from that of the column tip of ideal frame without defect. It may not be considered in advanced analysis of flexible structures. Based on the advanced analysis and design of the frame braced structure with high flexibility, the calculated ultimate bearing capacity usually fails because the deformation of the frame in the stage exceeds the limit requirement of normal use, and the structural design is ultimately controlled by the deformation performance. A practical advanced design method based on deformability for frame-braced structure with high flexibility is proposed.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU391

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