【作者】 刘丹；

【导师】 贾连光； 金路；

【作者基本信息】 沈阳建筑大学 ， 结构工程， 2016， 硕士

【摘要】 与传统的计算长度方法相比,高等分析和设计方法能直接得到结构整体的承载能力和变形性能,而不需要对结构中的各构件进行强度和稳定性验算。目前国内外关于高等分析方法的研究普遍集中在如何考虑各种非线性因素影响下结构的极限承载能力。但有研究表明,按承载力极限状态设计框架时,高柔的钢结构柱顶侧移往往超出结构正常使用极限状态的限值要求,结构的实际承载力是由结构的变形性能控制的。在影响结构变形性能的众多非线性因素中,以结构和构件的初始几何缺陷影响最为显著,而现阶段国内外规范关于初始几何缺陷的直接考虑方法,都保守的将缺陷布置在使结构和构件变形的同一方向,以致于多高层结构建模时的初始侧移很可能不满足结构整体垂直度的要求。针对上述问题,本文主要开展了如下工作:对二十层框架-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计算的结构极限承载力、构件内力和变形性能。对一榀单跨双层钢框架支撑结构进行了静载试验,重点研究了初始几何缺陷对结构变形性能的影响。由试验结果与有限元分析结果对比吻合较好,验证考虑随机初始缺陷有限元模型的正确性。采用蒙特卡罗法拉丁超立方抽样技术实现了考虑随机初始几何缺陷的建模方法,并通过ANSYS限元软件围绕二阶效应参数c、结构高宽比H/L、框架柱长细比λ和梁柱总线刚度比KZ对32层到50层钢框架支撑结构进行了 96种工况设计与参数分析。通过概率统计的方法确定考虑随机初始缺陷钢框架支撑结构的柱顶侧移和梁跨中挠度值,并与多种国内外规范考虑初始几何缺陷的方法进行对比分析。结果表明,在结构达到极限承载状态时,采用高等分析方法计算的结构侧移均比一阶弹性分析有显著增加,并且已超过规范规定的限值要求;考虑随机缺陷框架模型计算的结构侧移与无缺陷框架基本接近;采用中国规范假想力框架模型计算的结构侧移最大。分析结果表明,按承载能力极限状态设计的高柔钢框架支撑结构,其二阶侧移因超过了规范规定的限值要求而使其极限承载力失效,即结构的实际承载力由满足变形要求的容许承载力决定。根据大量的有限元分析结果拟合出高层钢框架支撑结构的二阶侧移近似计算公式,并通过算例验算其实用性。对由结构变形限值控制的多高层钢框架支撑结构提出了一种基于变形性能的实用高等设计方法。通过算例验证,基于变形性能的实用高等设计方法设计过程简便快捷,设计结果与基于承载能力状态设计方法一致,可以在高柔钢框架支撑结构的高等设计中广泛应用。更多还原

【Abstract】 Compared with the traditional method of length calculating,the ultimate capacity and deformation performance of a structure system can be analyzed directly by employing the advanced analysis method without checking the strength and stability of all separate members.At present,researches of the advanced analysis method at home and abroad generally focus on how to accurately consider the ultimate bearing capacity of structure under the influence of nonlinear factors.But some research results have shown that,when framework is designed according to the strengh limit state,their deformation checks usually do not satisfy the requirements for normal stage function for the high-rise steel frame structures.In addition,the actual bearing capacity is controlled by the structure allowable loading level within the deformation limiting values.The deformation performance of the structure is affected by many factors,especially the initial geometrical imperfections.Considering the existing researches of initial geometrical imperfections on the method at home and abroad,the imperfections have been arranged in the same direction in the layout structure and the component,which can lead to the fact that the lateral drifts may not meet the requirements of the whole structure perpendicularity when modeling multi-storey and high-rise structures.In view of the above problems,the main research has been carried out in this paper as follows:The structural design process for twenty layers braced frame structure has been studied in detail,in which the mothod of first order elastic analysis,the approximate second-order elastic analysis as well as advanced analysis method.Using the different design mothods above,the ultimate capacity,intenal force and deformation performance for structures have been analyzed comparatively.The scaled test of single span double-layer braced frame structure focuses on the influence of initial geometric imperfections on the deformation property.The test results and the finite element analysis results are in good agreement,which proves the correctness of the finite element model by taking random initial imperfection into consideration.The method of modeling about random initial geometrical imperfections will be achieved by employing Monte Carlo method and Latin hypercube sampling technique.A great deal of full-path analysis about thirty-two to fifty layers braced frame structure has been carried out by using finite element program ANSYS with different parameters,second-order influence parameter,which are the depth-width ratio,column slenderness ratio and general stiffness ratio of beam to column.According to the analysis results of the random distribution of imperfections,the lateral drifts and girder deflections will be determined by probability statistics.In addition,it will be compared with the results considering the initial geometrical imperfections at home and abroad were analyzed.The results shows that the lateral drifts obtained from advanced analysis are all significantly larger than those from first-order analysis,and exceed the limits set by the specification requirements,when the frame are designed by the ultimate limit state;The difference between the second-order deformation calculated by the random imperfection models and ideal frames is not obvious;The largest second-order defomations appear in the models for the hypothetical structure;In addition,when the Steel braced frame structures are designed by the ultimate limit state,the second-order deformations have been exceeded the requirements in the serviceability state,which means the allowable structural capacity is determined by the deformation limiting values for the structure.Based on a great deal of deformations gained from the parametric analysis,a simplified formula of second order lateral drifts for high-rise steel frame structure is provided,the applicability of which is validated through arithmetical example.For the multi-story and high-rise steel frame structures whose allowable load capacity are controlled by the deformation limiting values,a practical deformation performance-based advanced design method has been proposed.The practicality and efficienty of this method had been proved by the example,and results in accordance with the structures are designed by the ultimate limit state,which can be widely used for structure design of high-rise and flexible steel supporting frames.更多还原