基于关键构件失效的结构竖向防连续倒塌性能评价

发布时间：2018-04-26 17:52

本文选题：多层钢筋混凝土框架结构 + 关键构件　；参考：《西南交通大学》2014年硕士论文

【摘要】：本文以按我国规范设计的一栋平面布置规则的多层钢筋混凝土框架结构为算例,运用改进的线性动力拆除构件法和非线性静力pushover法对其连续性倒塌受力机制及连续性倒塌抗力机制进行了研究,并在此基础上介绍了结构防连续性倒塌的控制设计法,主要研究工作和成果如下： (1)多层钢筋混凝土框架结构关键构件的确定。关键构件的选取是结构防连续性倒塌机制分析和防连续倒塌设计的首要步骤。基于结构极限承载能力的概念,将构件拆除前后整体结构的极限承载能力的变化率定义为构件敏感性系数,提出了构件敏感性系数的计算方法。本文分别以平面框架和空间框架作为算例模型,将敏感性分析方法这一理论应用于算例中,验证了敏感性分析方法在平面框架和空间框架结构中的适用性,并通过计算得到了代表性构件的敏感性系数,为后续分析做好铺垫。 (2)针对按我国规范设计的多层钢筋混凝土框架结构,运用线性动力拆除构件法对其防连续性倒塌受力机制进行了研究。以往的结构防连续性倒塌动力分析时通常将结构的初始状态视为零应力,零位移状态,未考虑结构在未拆除构件前的静力平衡状态,显然这和实际情况是不符的。本文分析时,将结构的初始静力平衡状态考虑在内,改进了动力分析方法的加载方案,使得结果更加符合实际情况。通过改进后的线性动力拆除构件法,得到了结构在典型部位拆除后的动力响应以及稳态响应,通过同一层和不同楼层之间的对比,总结了结构防连续倒塌的内在受力机制及连续性倒塌的规律,为研究防连续性倒塌设计方法提供依据。 (3)采用非线性静力增量Pushover法,研究了按我国规范设计的典型RC框架结构的防连续倒塌抗力分布规律。基于结构关键构件的失效风险评估和关键构件的敏感性系数,提出了绝对倒塌概率的指标。同时,基于非线性静力增量法分析得到的局部区域竖向承载力全抗力曲线,提出了构件失效局部承载力储备的指标。前者从整体结构的角度评价结构发生连续性倒塌的可能性,后者从结构局部的的角度评价结构发生连续性倒塌的可能性。建议采用两个指标来综合评价结构的防连续性倒塌性能,给出了具体的评价方法,并对文中算例进行了评价。计算结果表明,角柱失效后结构易发生连续性倒塌,其次是边柱和中柱。这和线性动力分析时得到的结论吻合,为进一步研究防连续性倒塌设计方法提供依据。 (4)提出了结构连续性倒塌控制设计方法,并给出了该方法的具体流程。该方法包括轴压比评估法、简单评估法、详细评估法三个阶段,每一种方法的内容都是基于本文前几章的分析成果,通过循序渐进的方式对结构防连续倒塌设计提出了具体要求。
[Abstract]:In this paper, a multi-story reinforced concrete frame structure, which is designed according to the code of our country, is used as an example. The continuous collapse mechanism and the continuous collapse resistance mechanism are studied by using the improved linear dynamic demolition method and the nonlinear static pushover method. On the basis of this, the control design method for preventing the continuous collapse of the structure is introduced. The main research work and results are as follows: 1) determination of key members of multi-story reinforced concrete frame structure. The selection of key components is the first step to analyze the mechanism of continuous collapse and design of continuous collapse. Based on the concept of ultimate bearing capacity of structure, the change rate of ultimate bearing capacity of the whole structure before and after demolition is defined as the sensitivity coefficient of the member, and the calculation method of the sensitivity coefficient of the component is put forward. In this paper, the theory of sensitivity analysis is applied to the example of plane frame and spatial frame respectively, and the applicability of sensitivity analysis method in plane frame and spatial frame structure is verified. The sensitivity coefficient of representative components is obtained by calculation, which lays the groundwork for further analysis. 2) aiming at the multi-story reinforced concrete frame structure designed according to the code of our country, the mechanism of preventing continuous collapse is studied by means of linear dynamic demolition method. In the past, the initial state of the structure is usually regarded as zero stress and zero displacement state, and the static equilibrium state of the structure before the removal of the member is not considered, which is obviously not in accordance with the actual situation. In this paper, the initial static equilibrium state of the structure is taken into account, and the loading scheme of the dynamic analysis method is improved, which makes the results more in line with the actual situation. Through the improved linear dynamic removal method, the dynamic response and the steady response of the structure after the removal of typical parts are obtained, and the comparison between the same floor and different floors is carried out. The internal force mechanism and the law of continuous collapse of structures are summarized, which provides a basis for the study of the design method of continuous collapse prevention. In this paper, the nonlinear static incremental Pushover method is used to study the distribution of continuous collapse resistance of typical RC frame structures designed according to the code of our country. Based on the failure risk assessment of key structural components and the sensitivity coefficient of key components, an index of absolute collapse probability is proposed. At the same time, based on the total resistance curve of local vertical bearing capacity obtained by nonlinear static increment method, the index of local bearing capacity reserve for failure of members is proposed. The former evaluates the possibility of the continuous collapse of the structure from the viewpoint of the whole structure, and the latter evaluates the possibility of the continuous collapse of the structure from the point of view of the local structure. It is suggested that two indexes be used to synthetically evaluate the anti-collapse performance of the structure, and a concrete evaluation method is given, and an example is given. The calculated results show that continuous collapse of the structure occurs easily after the failure of the corner column, followed by the edge column and the middle column. This is consistent with the conclusion of linear dynamic analysis, which provides a basis for further study on the design method of continuous collapse prevention. 4) the design method of continuous collapse control is proposed, and the concrete flow of this method is given. This method includes three stages: axial compression ratio evaluation method, simple evaluation method and detailed evaluation method. The contents of each method are based on the analysis results of the previous chapters of this paper. The concrete requirements for the continuous collapse prevention design of the structure are put forward in a step-by-step manner.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU312;TU375.4

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