【作者】 张海燕；

【导师】 易伟建；

【作者基本信息】 湖南大学 ， 结构工程， 2005， 博士

【摘要】 结构的抗震性能评估是基于性能的抗震设计理论的主要研究内容之一,不同地震动水平下结构位移反应的概率分析是其难点也是关键所在。基于位移的抗震设计是实现基于性能的设计思想的重要途径,但目前对它的研究还处于概念性的讨论阶段,离实际应用和纳入规范还有较大距离。围绕结构的概率地震需求分析方法以及基于位移的抗震设计方法,本文进行了以下几个方面的研究工作: 1.目标位移估计是Pushover分析方法用于结构抗震性能评估的关键问题之一。能力谱法可以用来估计结构的目标位移,在该方法中弹塑性反应谱常用于需求曲线的建立。以往对弹塑性反应谱的研究主要集中于等延性强度需求谱。通过探讨等强度延性需求谱和等延性强度需求谱在概念及计算方面的区别,本文提出采用等强度延性需求谱作为结构的需求曲线,并结合由Pushover分析得到的能力曲线,对结构的目标位移及抗震性能进行评估。 2.通过引入结构的屈服水平系数以及建立等屈服水平延性需求谱,可以像弹性反应谱中的地震系数以及动力放大系数曲线一样,将地震动的幅值特性以及频谱特性分开考虑。收集大量的地震记录,并根据场地类型和特征周期进行分类和分组,在每组地震记录作用下对大量的双线性单自由度体系进行非线性时程反应分析。基于这些分析结果,对给定结构屈服水平以及基本周期条件下的延性需求的概率分布类型进行了假设检验,并通过多元非线性回归得到了不同场地条件下延性需求的统计参数,进而建立了概率延性需求谱。利用概率延性需求谱以及条件分布的性质,本文提出了确定性结构随机地震位移反应分析的简化方法以及概率地震需求分析的简化方法,并通过算例分析对方法的有效性进行了证明。 3.通过对大量的2自由度体系进行非线性时程反应分析,探讨了结构参数以及场地条件对2自由度体系位移及延性需求的影响规律。采用类似于单自由度体系的分析方法,获得了不同场地条件下2自由度体系的概率延性需求。利用单自由度体系与2自由度体系的概率延性需求分析成果,并结合结构的能力分析,本文提出了对不同支座形式的规则连续梁桥进行地震易损性分析的简化方法。 4.对常见的主要失效模式为下部破坏型结构,本文提出将其等效成2自由度体系进行Pushover分析,并推导了多自由度体系等效成2自由度体系的计算公式。当结构的非线性较强时,建议在弹性和非弹性反应阶段采用不同的形状向量来描述结构的顶点位移与楼层位移的关系。通过对几个多层框架结构进行分析,比较了5种改进的Pushover分析方法的精度及适用范围。 5.比较了两种常用的基于位移的抗震设计方法,在此基础上提出把由等强度更多还原

【Abstract】 Seismic evaluation of structural performance is one of the main research contents in performance-based seismic design theory. Probabilistic analysis of structural displacement responses for different seismic intensities is difficult but principal for performance evaluation. Displacement-based design is an important approach to realize the idea of performance-based design. However the current studies in this field are still at the stage of discussion about some concepts, and away from practical application and implementation into design codes. Focused on structural probabilistic seismic demand analysis and displacement-based seismic design, this dissertation involves the following work:1. Estimating the structural target displacement is essential for Pushover analysis method to be applied to the evaluation of structural seismic performance. The target displacement of a structure can be predicted by capacity spectrum method, where the demand curves are often constructed by elastic-plastic response spectra. The present research on elastic-plastic response spectrum is mostly on constant-ductility strength demand spectrum. After investigating the differences in conception and calculation between constant-strength ductility demand spectrum and constant-ductility strength demand spectrum, the former is proposed for the demand curves. Combined with the capacity curve from Pushover analysis, the target displacement and seismic performance of a structure can be estimated.2. The intensity and frequency content of an earthquake ground motion can be considered separately by introducing normalized yield strength coefficient and constructing constant-strength ductility demand spectrum, similar to the seismic factor and dynamic amplification factor curve in elastic response spectrum. According to the site types and characteristic periods, the collected records are classified. Under each set of records, nonlinear time history response analysis for plentiful bilinear single-degree-of-freedom systems (SDOF) is carried out. Based on these results, and conditional on given normalized yield strength coefficient and structural fundamental period, the probabilistic distribution type of ductility demands is checked by hypothesis test, also the mean and standard deviation of ductility demands are obtained by nonlinear multiple regression analysis. As a result, probabilistic ductility demand spectrum can be constructed. Utilizing probabilistic ductility demand spectrum and the characteristic of conditional probabilistic distribution, simplified更多还原