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关于结构振型参与系数和振型贡献的分析 总被引:1,自引:0,他引:1
采用振型分解反应谱法求解多自由度弹性体系的地震反应时,为了在满足所需计算精度的前提下减少工作量,需要对振型数量进行合理的选择,而振型数的确定主要取决于结构各阶振型对总体反应的贡献。通过数学推导,对振型贡献及振型数量的选择问题进行了研究。首先,讨论了振型参与系数的性质,在此基础上给出了能够反映结构振型贡献参数的数学表达式,对这些参数的力学含义进行了解释,并给出了相关证明;其次,对有效质量法、振型位移控制法等基于不同振型贡献标准的确定振型数的方法进行了分析比较,指出了其合理性和不足。本文研究对进一步理解结构振型贡献和振型数的选择问题具有一定的理论意义。 相似文献
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Carlos Sousa Oliveira 《Bulletin of Earthquake Engineering》2003,1(1):37-82
Earthquakes are known to be natural hazards that have affected tremendously historical constructions. Unfortunately, as far
as earthquake impacts are concerned, there are no world statistics to compare the suffering of populations or of the building
stock and their evolution in time, with the damage inflicted to the stock of historical constructions. Lately, a great effort
has been placed on engineering developments: (i) to better understand the seismic behaviour of historical construction and
(ii) to assess the benefits of different techniques for reinforcing these structures. However, a great deal of discussion
is still going on the type of reinforcement that should be applied, how effective it is and how much it costs. Research is
needed for helping in these decisions, by providing a more precise framework in this field. The aim of this review is to make
an overall insight on some of the available methods for assessing seismic vulnerability of historical constructions and on
how to use them in the case of occurrence of an earthquake. Given this occurrence, the objective is to minimize the effects
of aftershocks, avoid hurried demolition made under extreme pressure and help shore-up parts in risk of falling. The final
aim is also to help in the definition of strategies for the repair of the damaged patrimony, or as a measure to prevent damage
in future earthquakes for the most vulnerable cases. The paper is illustrated with the presentation of several examples published
in the literature where the author participated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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C. La Mura T. B. Yanovskaya F. Romanelli G. F. Panza 《Pure and Applied Geophysics》2011,168(1-2):201-216
It is an acquired result that, in order to enable realistic earthquake hazard assessment and reliable estimation of the ground motion response to an earthquake, three-dimensional velocity models have to be considered. In this paper we present a new analytical procedure for determining the seismic wavefield in a 3D anelastic model based on the combination of the ray theory with the modal summation method. The proposed procedure has been validated by considering the three-dimensional model of the Kanto basin (Japan) available in the literature. Three-dimensional simulations were performed for the 1990 Odawara earthquake. The results obtained were compared both with recorded signals and with simulations available in the literature for several stations located within the Kanto basin. Besides the advantage of being a useful tool for assessment of seismic hazard and seismic risk reduction, it is characterized by high efficiency, in fact, once the study region is identified and the 3D model is constructed, the computation, at each station, of the three components of the synthetic signal (displacement, velocity, and acceleration) takes less than 3?h on a 2?GHz CPU. 相似文献
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Růžek Bohuslav Zedník Jan Klíma Karel Ruprechtová Libuše 《Studia Geophysica et Geodaetica》2000,44(2):175-187
The routine location of regional seismic events using data from the Czech National Seismological Network (CNSN) is based on Pn, Pg, Sn, Sg phases. A simple velocity model derived from Kárník's (1953) interpretation of an earthquake in Northern Hungary in 1951 has hitherto been used. At present, numerous local seismic networks record and locate local events, which are occasionally recorded at regional distances as well. Due to the relatively small dimensions of local networks, hypocenters (and origin times) determined by a local network might be considered as nearly exact from the point of view of regional-scale CNSN. The comparison of common locations performed by CNSN and by a local network enables us to estimate the accuracy of CNSN locations, as well as to optimize a simple velocity model. The joint interpretation of the CNSN bulletin and the catalogues of four local seismic networks WEBNET, OSTRAVA, KLADNO and LUBIN produced a new ID velocity model. The most frequent epicentral error in this model is less than 5 km, and most foci lie up to 15 km from the true position. The performed analysis indicates bimodal distribution of Sn residuals. 相似文献
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增大柱端抗弯承载力是抗震"能力设计"措施中引导钢筋混凝土框架结构形成梁铰型有利耗能机构的关键措施。本文以6层确定性钢筋混凝土框架结构为分析对象,通过结构易损性分析评估了不同强柱系数取值对钢筋混凝土框架结构抗震性能的影响。结构易损性分析表明增大柱端抗弯承载力是改善结构抗震性能的有效措施,增大强柱系数提高了结构的变形能力,使不同破坏极限状态之间形成较大的"梯度",对防止强烈地震作用下结构的突然倒塌提供了预示。结构易损性曲线对评估结构抗震性能、选用合适的目标强柱系数提供了量化标准。 相似文献
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考虑到结构抵抗地震作用的机制为结构和地震动的不确定性与非线性相互耦合的过程,采用增量动力分析(IDA)考虑地震动的不确定性,选取16条地震动记录,基于OpenSEES的有限元建模理论对13榀平面RC框架结构进行基于IDA方法的地震易损性分析,分别讨论轴压比、高宽比、混凝土强度以及纵筋强度等结构参数对RC框架结构抗震性能的影响。结果表明:柱轴压比对结构抗震性能的影响显著,而高宽比对结构抗震性能的影响不明显;在保证柱轴压比相近的前提下,提高柱混凝土强度能够提升结构的抗震性能;相同地震作用下梁柱配置纵筋强度较高的框架结构达到立即使用(IO)状态和生命安全(LS)状态的概率较配置纵筋强度较低的大,配置纵筋强度较高的框架结构较配置纵筋强度较低的表现出更好的抗倒塌能力。 相似文献
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淮南台电磁扰动数据变化特征及影响因素初探 总被引:1,自引:0,他引:1
通过对淮南地震台2009~2011年电磁扰动观测数据的分析,得到如下结论:①电磁扰动三个通道均有明显的日变化规律:00:00~07:00观测数据在均值附近波动,无脉冲变化;07:00~22:00三个通道的变化幅度均出现明显增强,22:00~24:00又恢复平稳变化。通过与环境因素及淮北台电磁扰动的对比,认为环境噪声水平是影响电磁扰动日变的主要因素。②傅里叶分析结果显示电磁扰动子夜均值有明显的365、183、122 d周期,其中365 d年周期振幅最大。第一、二通道电磁扰动子夜均值冬季低,夏季高,第三通道与前两通道年变化相反。③温度对电磁绕输出信号影响的实验初步证实了温度改变时,电磁扰动三个通道的输出均有同步的响应,且理论计算与实际观测的变化幅度基本一致。因此,认为电磁扰动的年变主要是受气温的影响。 相似文献
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分时段研究降雨、钻孔水位、工程施工等因素对青岛地震台体应变的影响,研究结果表明:钻孔水位反映区域地下水主要由降雨补给,降雨下渗改变地下水状态,并影响体应变观测;青岛体应变与钻孔水位的相关性及其周期特性均在2015年前后出现变化,可能与2015—2016年降雨偏少及工程施工有关;2018年1月17日台站钻孔施工很可能改变了体应变周围岩石孔隙环境,并扩大孔隙压力作用系数,可解释2018年3月以来水位小幅上升引起的体应变显著压性上升现象,受钻孔施工的影响,体应变与钻孔水位相关性的滞后特征明显减弱。 相似文献