地震工程的研究和应用--回顾与展望

近百年来的地震工程研究取得了长足的进展，推进了人类的防震减灾事业。当前，面临社会经济发展对公众和工程安全提出的越来越高的要求，随着材料科学、信息和计算机技术、机械工程等领域高新技术的迅速发展，地震工程研究也进入了一个新的阶段。性态抗震设计、结构振动控制和健康诊断成为推进和扩展地震工程研究的前沿领域。     

考虑强地面运动持时影响的概率地震需求模型

选择合理的持时衰减关系,利用Monte-Carlo方法,抽取持时样本,根据震级M、震中距R和局部场地土壤条件S以及持时样本,选择符合条件的实际地震波记录,并进行合理的调值,对一座钢筋混凝土桥墩进行了非线性动力时程分析.对比强地面运动持时与能量需求参数和累积破坏参数的相关性,发现:幅值、频谱和持时对能量需求参数和累积破坏参数的影响是强烈耦合的,且强地面运动持时对两者的影响比较显著;在选择结构第一模态周期谱加速度和合理的能量需求参数,并分别作为地面运动强度参数IM和EDP建立概率地震需求模型时,要考虑持时的影响.     

Performance-based seismic design of nonstructural building components:The next frontier of earthquake engineering

With the development and implementation of performance-based earthquake engineering,harmonization of performance levels between structural and nonstructural components becomes vital. Even if the structural components of a building achieve a continuous or immediate occupancy performance level after a seismic event,failure of architectural,mechanical or electrical components can lower the performance level of the entire building system. This reduction in performance caused by the vulnerability of nonstructural components has been observed during recent earthquakes worldwide. Moreover,nonstructural damage has limited the functionality of critical facilities,such as hospitals,following major seismic events. The investment in nonstructural components and building contents is far greater than that of structural components and framing. Therefore,it is not surprising that in many past earthquakes,losses from damage to nonstructural components have exceeded losses from structural damage. Furthermore,the failure of nonstructural components can become a safety hazard or can hamper the safe movement of occupants evacuating buildings,or of rescue workers entering buildings. In comparison to structural components and systems,there is relatively limited information on the seismic design of nonstructural components. Basic research work in this area has been sparse,and the available codes and guidelines are usually,for the most part,based on past experiences,engineering judgment and intuition,rather than on objective experimental and analytical results. Often,design engineers are forced to start almost from square one after each earthquake event: to observe what went wrong and to try to prevent repetitions. This is a consequence of the empirical nature of current seismic regulations and guidelines for nonstructural components. This review paper summarizes current knowledge on the seismic design and analysis of nonstructural building components,identifying major knowledge gaps that will need to be filled by future research. Furthermore,considering recent trends in earthquake engineering,the paper explores how performance-based seismic design might be conceived for nonstructural components,drawing on recent developments made in the field of seismic design and hinting at the specific considerations required for nonstructural components.     

钢筋混凝土结构的屈服位移Chopra能力谱损伤分析与性能设计

本文提出了应用地震损伤指数评定结构抗震性能要求的方法。首先，建立了抗力谱曲线和结构损伤指数的关系，得到了反映不同设防水准损伤目标的结构地震务容许延性系数；其次，应用屈服位移Chopra能力谱法确定地震损伤延性系数；然后，提出了应用结构地震损伤延性系数和容许延性系数之间的关系来评定结构抗震性能的方法；最后，通过算例说明了本文方法实施的步骤。     

广州花园酒店"白金五星级酒店"结构改造基于性能的可行性研究

广州花园酒店原结构及改造后结构均不满足我国现行规范的抗震构造要求。本文依据基于性能的抗震设计思想,提出结构宏观上的层间位移角目标和微观上的结构构件变形及损伤目标,采用PKPM系列2005年版SATWE和ETABS 9.0中文版进行结构弹性分析,采用PKPM系列EPDA和美国Buffalo大学的IDARC 2D 6.0进行弹塑性静力推覆分析和弹塑性动力时程分析,并采用TNO公司的DIANA8.0进行单榀剪力墙的极限承载力分析,研究结构是否满足设定的整体及结构构件性能目标要求,确保改造后的结构达到"小震不坏、中震可修、大震不倒"的要求。     

基于性能的钢筋混凝土框架剪力墙结构地震易损性分析

以某典型的20层钢筋混凝土框架剪力墙结构作为研究对象,研究基于性能的RC框架剪力墙结构易损性分析方法。首先选择合适的地震动记录,以0.2g为步长进行调幅后,建立300个结构-地震动样本空间,并确定结构损伤指标和性能参数;然后应用增量动力分析方法计算结构的地震动力响应,选择基本周期加速度反应谱为地震动参数,以研究结构反应的不确定性,并深入分析地震动参数与结构地震需求参数的关系;在此基础上,建立该结构基于加速度反应谱的易损性曲线进行结构易损性分析与评估。结果表明：随着地震动强度的增大,IDA曲线由单调增加变为非单调增加,分位曲线（16%,50%和84%）可以准确地衡量结构的性能;框剪结构在地震作用下的抗震性能表现良好,随着地震强度的增长,各性能超越概率大小的增长速度是不同的。     

地震地面运动特性对结构地震需求的影响研究现状

在结构抗震设计和分析中,地震地面运动特性(用幅值、频谱特性和持时表示)的变异性对于结构地震需求的影响最大.震害经验表明,各类结构的震害均表现为这三个基本要素综合影响的结果.因此,从地震工程学和结构抗震两个方面,对国内外结构地震需求分析研究现状进行了较为全面的论述,包括分析方法、研究内容、影响因素等,重点论述了地面运动三要素对结构地震需求的影响,提出了存在的问题和今后尚需开展的研究工作.     

Developing collapse fragility curves for base-isolated buildings

Seismic isolation technique is increasingly used both for the design of new buildings and for the seismic retrofit of existing buildings. Nevertheless, so far, little attention has been paid on the collapse capacity of these structures, mainly because it requires refined nonlinear models and careful consideration of different sources of uncertainties. To fill this gap, a set of collapse fragility functions for existing reinforced concrete-frame buildings, designed for gravity loads only and then retrofitted with different isolation systems (including rubber-based and friction-based isolation systems), are derived in this study. For completeness, buildings with low and high seismic resistance are also considered. Collapse fragility functions are derived through incremental dynamic analysis, considering different collapse conditions both for isolation system and superstructure. For each case study building, mean and dispersion values are obtained considering both aleatory and epistemic uncertainties, due to record-to record and model variability, respectively. Finally, some comments on the possible use of the results of this study for practical applications are made.     

基于性能的既有钢筋混凝土建筑结构抗震评估与加固技术研究

根据我国现行的建筑结构抗震规范,无论是新建建筑结构的抗震设计还是既有建筑结构的抗震评估与加固,均通过小震弹性承载力计算 抗震延性构造措施来达到"小震不坏、中震可修、大震不倒"的抗震设防目标(对于不规则且具有明显薄弱部位的建筑结构还需要进行罕遇地震作用下的弹塑性层间变形验算)。对于抗震延性构造措施不满足现行规范的既有建筑结构的评估、改建、扩建,如果仅通过小震弹性的承载力计算,显然无法达到"大震不倒"的目标。本文通过引入国际上先进的基于性能的结构抗震思想,以结构层间位移和结构构件变形作为性能目标,从定量上解决了既有钢筋混凝土建筑结构的抗震评估与加固问题。     

Intensity measure conversion of fragility curves

In seismic risk assessment of structures, fragility functions are the probabilistic characterization of vulnerability at the component and/or structural level, expressing the probability of failure as a function of a ground motion intensity measure (IM). Fragility curves, in general, are structure- and site-specific, thus a comparison of fragility curves, then of vulnerability, is not straightforward across multiple structures. Also, it could be the case that hazard at a site of interest is not available for the IM originally considered in the fragility assessment. These situations require to convert fragility curves from an original IM to a target one. The present study addresses a hazard-consistent probabilistic framework for converting spectral acceleration-based IMs from an original IM to a target IM at a given site. In particular, three conversion cases, under different assumptions on the explanatory power of the involved IMs with respect to structural failure, are discussed: (a) a vector-valued IM consisting of the original and target IMs, magnitude, and source-to-site distance; (b) a vector-valued IM consisting of the original and target IMs; and (c) the original (scalar) IM only, assuming that structural response, given the IM, is statistically independent of the other ground motion variables. In this framework, the original fragility functions are characterized using the state-of-the-art methods in performance-based earthquake engineering, then the fragility curves as a function of the target IM are evaluated through applications of the probability calculus rules, ensuring consistency with the seismic hazard at the site of interest. The conversion strategy is illustrated through the applications to three-, six-, and nine-story Italian code-conforming reinforced concrete buildings designed for a high-hazard site in Italy. The study shows that, in most of the cases, the converted fragility curves have agreement with the reference curves directly developed in terms of the target IM. Cases in which least agreement was found are likely due to the models used to obtain the terms required by the conversion equations.