【作者】 公茂盛；

【导师】 谢礼立；

【作者基本信息】 中国地震局工程力学研究所 ， 防灾减灾工程及防护工程， 2002， 硕士

【摘要】 结构在强烈地震作用下，一般会进入非线性工作状态。事实上，震害调查结果表明，结构物在强烈地震作用下，确实曾进入非线性工作状态，具体表现有：裂缝或其它形式的非弹性变形发生、经历地震后有永久变形存在等等。结构一旦进入非线性阶段，其地震总输入能主要由结构的非弹性变形和阻尼来耗散。因此，从物理意义上来讲，能量才是对结构物进行非弹性设计或对结构物进行地震破坏评估的最合理参数。目前，基于能量的性态设计方法及理论也是地震工程中一个热门的研究课题。本文的主要工作就是利用所掌握的地震动记录，采用两步回归法对地震动的各种能量参数进行回归分析，找出地震动的能量参数随震级、距离等参数的衰减关系，为基于能量的方法能够应用到抗震设计及震害评估等实际工程中奠定基础。 本文所做的主要工作摘要如下： 1．建立了一个强震记录数据库。 作为地震工程研究的重要基础性资料，强震记录的重要性不言而喻。尽管目前世界范围内取得了大量强震记录，但是这些记录具有格式形式不统一、参数不完备等缺点。对大部分地震记录来说，尤其缺少便于统计应用的矩震级及断层距等实用数据。因此，本文处理了美国西部California州共15次地震中的强震记录，将所有记录的格式做了统一化处理，特别是补充、增加了供统计应用的矩震级和断层距等信息。 2．介绍了能量反应谱的概念及算法。 结构地震反应的能量分析方法是一种能够较好的反映结构在强地震动作用下非线性性质以及地震动三要素(幅值、频谱特性和持时)对结构抗震性能影响的方法。目前常用的反应谱，无论是弹性或非弹性的，一个最大的缺憾是它们都没有充分考虑输入地震动持时的影响，但在能量谱中由于要反映随着持时增长引起的能量变化，因而持时影响得到了充分的考虑，这是能量谱的一个十分重要的特点。本文对能量反应谱的概念、计算方法、性质特点做了详细的总结及论述，并比较了几种能量反应谱的联系和差别。 3．论述了两步回归统计拟合方法。 强震记录的震级和距离是具有相关性的，通常距离大的强震记录往往对应大的震级，这一点早被众多的研究者所认同。这种相关性是固有的，也是不可避免的。本文中所采用的矩震级和断层距就具有这种相关性。因此，在回归分析时，必须考虑这种震级和距离耦合作用可能会带来大的误差。为了将震级和距离的这种相关性解耦，避免其给回归结果带来一定的不合理性，Joyner和Boore在1981年提出了两步回归法，即将震级和距离分两步统计。其后众多的研究者在对地震动参数进行统计分析时，几乎都是采用两步回归法。事实证 中国地震局工程力学研究所硕士学位论文一明，两步回归法的确能够将震级距离解耦，可以减小这种相关性带来的误差。本文对两步回归法做了详细的论述，尤其对第二步回归分析时的加权矩阵做了细致的分析，并编制了计算程序。 4．地震动能量衰减规律的统计分析。 本文将所选的强震记录按场地条件分为了三类，对每一条强震记录（本文中一条记录包含两个水平分量一个竖向分量）的两个水平分量分别计算了其“绝对”输入能量谱、“相对”输入能量谱、吸收能量谱和滞回能量谱等四种能量反应谱（取等效速度谱）。对每一条记录，取了两个分量所计算的能量谱的几何平均值，选择了衰减模型，利用两步回归法，对这些能量等效速度谱做了统计拟合分析，得出了地震动四种能量反应谱随震级、距离等参数的衰减规律。详细分析了场地条件、震级、延性系数和距离等参数对地震动能量衰减的影响。并与其它己有的研究结果做了对比，验证了本文所计算能量反应港及统计拟合使用程序的正确性，同时也验证了本文结果的正确性。并且得出了一些比较重要的结论。更多还原

【Abstract】 The structures are generally put into non-linear state under the strong ground motion. In fact, the investigation of earthquake disaster shows that it is true. First, there are inelastic deformations of structures after intensive earthquake. Second, there are permanent deformations of structures after intensive earthquake. Once the structures step into inelastic work state, the earthquake input energy is dissipated by the damp and inelastic distortion. Hence, the energy is the best parameter when a structure is inelastic designed or evaluated for seismic hazard. Presently, the ultimate-state seismic design based on energy has been concerned in the field of earthquake engineering. Based on 266 strong ground motion records from 15 earthquakes in America, an attenuation relationship was used to relate energy spectra to earthquake magnitude, source-to-site distance, and site class. The purpose of this study is to make a foundation of energy-based design and seismic hazard analysis.The main achievements of this study could be summarized as follows:1. Establishment of an improved strong ground motion database.Strong ground motion records, one of the experimental resources for earthquake engineering, have made an important role in earthquake engineering research. Although there are a large amount of strong ground motion records all over the world, for the mass, there are disadvantages such as having no uniform format, short of parameters and so on. So, records from 15 earthquakes in the U.S. are checked in this paper. Especially moment magnitude and fault-distance are added.2. Introduction of concept and calculating method for energy spectra.In ultimate-state seismic design, energy spectra have been used for the reliable indices of seismic motions that determine their influences on structural failure and non-linear response. Also, energy of ground motion can be viewed an index to incorporate the duration effect on structures, because longer duration usually induces a large energy demand. The duration of ground motion is so sufficiently taken into account. The concept and characteristic of energy spectra are introduced in detail in the paper.3. Discussion the two-stage regression analysis method.There is a good relativity between the magnitude and distance. This kind of relativity is inherent and inevitable. If the coefficients of attenuation model were solved simultaneously, errors in measuring magnitude would affect other coefficients. In order to minimize the biased result, a two-stage regression method suggested by Joyner and Boore is used to decouple the dependence of magnitude and distance. In fact, the two-stage regression method has been proved effective to decouple the coupling of the magnitude and distance, and minimize the regression error. The two-stage method, including the weighting matrix important for the stage-two regression, is discussed detailedly in the paper.4. Analysis of the attenuation law of ground motion energy.All records are classified into three site conditions. For the two components of a record, two energy equivalent spectra are calculated, and the geometric mean of the two spectra are adopted to analysis by two-stage regression method using an attenuation model. Then the attenuation law is attained. And the effect, of the parameters such as site conditions, magnitude, ductility and distance on the energy spectra is analysis detailedly in the paper. In order to validate the validity of the result in the paper, the result of Zhou and Uang (2000) is used to contrast with the result. Some important conclusions are made at last.更多还原