钢框架抗连续倒塌与抗地震倒塌性能分析

发布时间：2018-06-24 02:20

本文选题：连续倒塌 + 地震倒塌　；参考：《江苏科技大学》2017年硕士论文

【摘要】：如今,建筑结构遭遇地震、冲击等荷载导致结构发生倒塌事故,正日益受到工程界的关注。结构的倒塌问题分为竖向连续倒塌和侧向地震倒塌两类,结构连续倒塌是指在正常使用条件下,由于爆炸、冲击等荷载造成的破坏,造成建筑结构局部损失而逐渐扩大至全范围,最终形成倒塌。而结构抗地震倒塌能力,即结构在遭遇地震荷载时,能否基于结构的功能需求,使结构的侧向倒塌破坏控制在一定的范围,使结构在不同的地震动强度下达到不同的性能状态。这些问题正受到工程界日益广泛的关注。本文以SAP2000有限元软件作为仿真分析工具,首先,采用拆除构件法对钢框架在冲击、爆炸等荷载作用下,导致底层柱失效时,进而造成结构竖向连续倒塌的情况进行分析研究,并比较了钢框架底层层高的不同,对结构抗连续倒塌的影响。其次,采用IDA分析方法,对钢框架抗地震倒塌分析研究,则通过对地震动不断调幅,进行结构的非线性时程分析,得出结构的抗地震倒塌能力性能点,同时也讨论了钢框架底层层高不同对结构抗地震倒塌的影响。本文的主要研究工作如下:(1)建立平面钢框架模型,在对结构进行抗连续倒塌分析时,采用非线性静力分析方法、非线性动力分析方法、竖向IDA方法,研究了结构抗连续倒塌的性能。并分别从边柱破坏和中柱破坏这两种构件破坏的方式进行分析。发现边柱破坏后剩余结构抗连续倒塌承载力更差,失效点竖向位移更大,因而边柱破坏比中柱破坏更具威胁性。同时,发现构件失效后结构内力进行重分配时,失效柱的相邻构件承担绝大部分多余荷载,故加强对敏感构件的相邻构件的设计,能够有效防止结构连续倒塌破坏。(2)对建筑结构进行抗连续倒塌分析时,研究了钢框架底层层高不同对结构抗连续倒塌的影响,发现当底层层高增幅不高于标准层层高的1.4倍时,结构发生连续倒塌破坏的概率不会明显提高。同时,为了对比非线性静力分析与非线性动力分析之间的差异,引进基于荷载定义的动力放大系数,发现结构进入塑性后动力放大系数值为1.3左右,而美国规范取值为2.0,偏于保守。(3)采用IDA方法,选取多条地震波,对钢框架进行抗地震倒塌研究,对地震动强度进行调幅,直至结构达到极限状态。对由地震动强度调幅得到的分位曲线统计分析,得出对应极限状态下的破坏点地震动强度指标,随后对结构进行地震易损性分析,拟合出结构的地震倒塌易损性曲线,最终得出结构抗倒塌储备系数。比较分析钢框架底层层高不同对结构抗地震倒塌的影响,同时也分析钢框架底层层高不同引起的抗倒塌储备系数的变化,通过控制底层层高增幅,避免结构抗震倒塌概率的显著提高。
[Abstract]:Nowadays, structural collapse caused by earthquake, shock and other loads is attracting more and more attention. The collapse problem of structure can be divided into vertical continuous collapse and lateral earthquake collapse. The continuous collapse of structure refers to the damage caused by explosion, shock and other loads under normal service conditions. The local loss of building structure is gradually extended to the whole area and finally collapses. The ability of structure to resist earthquake collapse, that is, whether the structure can be based on the functional requirements of the structure to control the lateral collapse of the structure in a certain range, and make the structure in different ground motion intensity to achieve different performance state. These problems are being paid more and more attention by the engineering circles. In this paper, SAP2000 finite element software is used as a simulation tool. Firstly, the method of removing members is used to analyze and study the vertical collapse of the steel frame, which results in the failure of the bottom column when the steel frame is subjected to impact, explosion and other loads. The influence of the height of the bottom layer of the steel frame on the continuous collapse of the structure is compared. Secondly, by using IDA analysis method, the seismic collapse resistance of steel frame is studied. Through the continuous amplitude modulation of ground motion, the nonlinear time history analysis of the structure is carried out, and the performance points of the seismic collapse resistance of the structure are obtained. At the same time, the influence of the height of the bottom layer of the steel frame on the seismic collapse of the structure is also discussed. The main research work of this paper is as follows: (1) the plane steel frame model is established, and the nonlinear static analysis method, nonlinear dynamic analysis method and vertical IDA method are used to analyze the continuous collapse of the structure. The performance of the structure against continuous collapse is studied. The failure modes of side column and middle column are analyzed respectively. It is found that the bearing capacity of the residual structure after failure is worse and the vertical displacement of the failure point is greater, so the failure of the edge column is more threatening than the failure of the middle column. At the same time, it is found that when the internal force of the structure is redistributed after the failure of the component, the adjacent members of the failure column bear most of the redundant load, so the design of the adjacent members of the sensitive members is strengthened. It can effectively prevent the continuous collapse and damage of the structure. (2) the influence of the height of the bottom layer of the steel frame on the continuous collapse of the structure is studied when the height of the bottom layer is less than 1.4 times of the standard layer height in the analysis of the continuous collapse of the building structure. The probability of continuous collapse and failure of structures will not be significantly increased. At the same time, in order to compare the difference between nonlinear static analysis and nonlinear dynamic analysis, the dynamic magnification factor based on load definition is introduced. In the United States, the value of code is 2.0, which is conservative. (3) the seismic collapse resistance of steel frame is studied by using IDA method, and the amplitude modulation of ground motion intensity is carried out until the structure reaches the limit state. Based on the statistical analysis of the quartile curve obtained from the amplitude modulation of ground motion intensity, the index of ground motion intensity corresponding to the limit state is obtained, and then the seismic vulnerability of the structure is analyzed, and the seismic collapse vulnerability curve of the structure is fitted. Finally, the structure anti-collapse reserve coefficient is obtained. The influence of the height of the bottom layer of the steel frame on the seismic collapse resistance of the structure is compared and analyzed. At the same time, the variation of the reserve coefficient of the collapse resistance caused by the different height of the bottom layer of the steel frame is analyzed, and the increase of the height of the bottom layer is controlled. The probability of avoiding seismic collapse of structures is significantly increased.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU391

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