【作者】 陈诚；

【导师】 李维滨；

【作者基本信息】 东南大学 ， 土木工程建造与管理， 2016， 硕士

【摘要】 目前规范中的结构抗震设计方法可以总结为“三水准,两阶段”,以保证在地震作用下,结构不会发生倒塌,危及使用者的生命安全。但是,随着社会经济的发展,往往结构内部的设备及一些非结构构件的重要性和价值超过了结构本身,在强震作用下,即便结构不倒塌,其造成的经济损失和社会损失也是国家不能承受的。因此,前人在基于性能设计方法的基础上提出了结构地震易损性分析,从概率的角度研究结构在不同地震强度作用下发生各种破坏状态的概率。目前,在研究钢框架结构的地震易损性过程中,均以平面钢框架为研究对象进行易损性分析,去指导抗震设计与灾后评估。实际上,结构是以空间的形式存在,这种简化的方式对结构的抗震性能评估是否准确有待商榷。本文以依据现行规范设计的8度抗震和7度抗震条件下的五层钢框架结构为研究对象。分别对比研究于8度抗震条件下空间钢框架结构和平面钢框架结构多种性能指标的易损性曲线,阐明了研究空间钢框架结构易损性的必要性。据此分别对8度和7度抗震条件下空间钢框架结构的地震易损性分别进行研究,验证了现行规范设计结果的抗震安全性,获得了一些有价值的成果。本文的主要工作与成果如下：本文首先总结了结构抗震理念的发展、基于规范的钢框架抗震设计方法以及设计师们把控结构抗震性能的设计思路。接着以实际工程为背景,对8度和7度抗震条件下的五层钢框架结构分别进行了设计,以设计成果建立了7度抗震下的空间钢框架、8度抗震空间和平面钢框架三个模型作为本文地震易损性的研究对象。其次,考虑地震作用的随机性以及结构自身参数的随机性,采用拉丁超立方随机抽样技术对三种结构各生成了100个结构-地震动随机样本。选取顶点位移最大角、层间位移最大角和位移延性比作为地震需求参数,对300个结构-地震动样本运用动力弹塑性时程分析的方法逐一进行概率地震需求分析,对分析结果进行对数线性回归分析,得出地震需求参数与地震强度参数之间的函数关系。然后,本文对300个样本进行概率抗震能力分析,通过静力弹塑性分析,得出每个样本的Pushover曲线,计算出结构的屈服位移,基于规范定义的结构不同性能水准,利用该曲线研究结构破坏过程,提出了量化性能界限值的方法,以此确定各性能指标对应的不同极限状态的界限值。最后,根据概率地震需求分析与概率抗震能力分析的结果,对研究对象进行概率地震易损性分析。采用基于传统可靠度的理论分析方法来研究在不同强度地震作用下结构地震需求超越抗震能力的概率,即结构失效概率。分别绘制8度抗震平面钢框架结构、8度抗震空间钢框架结构和7度抗震空间钢框架结构以结构的顶点最大位移角(RDA)、层间最大位移角(ISDA)和位移延性比(μd)作为性能指标的易损性曲线,并进行多方向比较分析,有如下结论：对比8度抗震平面钢框架和8度抗震空间钢框架的易损性曲线,得出以平面钢框架代替空间钢框架作为研究对象对结构抗震性能的判定在局部上是不安全的;对比分析了按照不同方法定义结构性能限值作出的易损性曲线的不同,以本文使用的量化性能界限值的方法可以保证各性能指标的界限值对应的结构破坏状态在同一个性能点上,建议在研究易损性课题过程中采用本文定义的方法；对比分析了利用不同指标画出的地震易损性曲线的差异性,得出结论为,以层间最大位移角(ISDA)作为性能指标时,结构在地震作用下的失效概率最大,建议采取ISDA指导结构设计,以保证安全；利用以层间位移最大角指标画出的易损性曲线,统计出按照抗震设防8度设计的钢框架结构与按照抗震设防7度设计的钢框架结构在“小震、中震、大震”作用下的失效概率,可知,按照规范设计的钢框架结构在小震和中震作用下,可以保证性能,在大震作用下,倒塌概率较大,建议采用基于性能的抗震设计方法来设计重要性等级较高工程结构。更多还原

【Abstract】 At present, Standard seismic design method can be summarized as "three levels, two stages", preventing the structure from collapsing and protecting the users. However, with the development of social economy, the equipment and non-structural members are more important and valuable than the structure itself. Even if the structure does not collapse under the earthquake, the economic loss is unbearable to the country.Therefore, based on performance design method, predecessors come up with the structural seismic vulnerability analysis which evaluate the seismic performance comprehensively and calculate the probability of failure states under different earthquake intensity from the perspective of probabilistic. Currently,2D frame is used to be object of study during the seismic vulnerability analysis. Analysis result of it is used to guiding the seismic design and evaluating loss.In fact, the structure is special. Consequently, whether the evaluation for seismic performance of the structure is accurate or not can not be ensured.The five storey steel frame structure under 7 and 8 degree earthquake resistance based on the existing design standard has been considered as the research object. The fragility curves of different performance index for the spatial steel frame and the plane steel frame under 8 degree seismic condition are studied respectively. The necessity of the research on the vulnerability of the spatial steel frame is expounded. Accordingly, the seismic vulnerability of the spatial steel frame structures under 8 and 7 degrees earthquake resistance are studied respectively. The seismic safety of the design results based on existing standard is verified, and some valuable results are obtained. The main work and results of this paper are as follows:First of all, the development of the structural seismic concept is summarized and seismic design method of steel frame to control performance is introduced in detail. In addition, based on the practical engineering, the space steel frame under 7 degree earthquake resistance, the space steel frame and the plane steel frame under 8 degree earthquake resistance are established.Secondly, considering the randomness of earthquake action and the structure itself,100 samples for each of the three structures were generated by the Latin hypercube sampling technique. RDA, ISDA and μd is choosed to be the probabilistic seismic demand parameter. The log linear regression analysis is performed to the 300 samples, getting the function relation between the seismic demand parameters and the seismic intensity parameters.What’s more, probabilistic seismic capacity analysis must be done on these samples, through the static elastic plastic time history analysis, the pushover curve of the samples will be obtained and the yield displacement of the structure is calculated. Based on the different performance level of the structure defined by the specification and the failure process of the structure, the method of quantitative performance threshold value is proposed. the limit values of different each performance index are determined.Lastly, according to the results of probabilistic seismic demand analysis and probabilistic seismic capacity analysis, probabilistic seismic vulnerability analysis is performed. Theory based on traditional reliability analysis method is used to study the failure probability of the seismic demand beyond the seismic capacity. Use the vertex maximum displacement angle (RDA), the maximum interlayer displacement angle (ISDA) and the displacement ductility ratio (μd)as the performance index to draw seismic fragility curves. Conclusions which is based on the analysis are as follows:The seismic fragility curves of the plane steel frame structure under 8 degree earthquake resistance are compared with the fragility curves of spatial steel frame under 8 degree earthquake resistance, obtaining the influence of different research objects on the seismic behavior of the structure.The reason of the difference between two structures has been proposed. Furthermore, the vulnerability curves of performance index limit difined by different method are analyzed. Method for quantifying performance limits proposed by this paper will ensure that the damage state of each index is unified. Finally.compare and analysis the difference of the seismic fragility curves among these index, indicating that the ISDA is the most appropriate index of all. ISDA will be advised to be the design index to ensure the safety. According to the fragility curves of ISDA, failure probability of different states for the space steel frame under 7 degree earthquake resistance and the space steel frame under 8 degree earthquake resistance can be educed, indicating that the structures designed according to cord can keep safe under "small earthquake"and "medium earthquake".However, Under the major earthquake, the collapse probability is too high.Therefore, Seismic design method based on the performance should be applied in the design of the engineering structure with a high level of importance更多还原