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中美欧储罐抗震规范中地震作用的比较研究 总被引：3，自引：0，他引：3
对比分析了中国、美国和欧州国家储罐抗震设计规范在抗震设防基准、设防目标、设计参数、储罐简化模型、设计反应谱和地震力降低系数等方面的不同特点,比较各规范设计地震作用的大小.研究表明:我国鉴定标准、美国API650和欧洲EC-8的抗震设防水准基本相当,而欧洲EC-8的抗震设防目标偏低.对于中等类型场地上的低自振周期储罐,我国鉴定标准设计地震作用与美国API650相当,但低于欧洲EC-8设计值,鉴定标准的晃动波高大于欧洲EC-8.另外以我国常用系列浮顶罐和大型浮顶罐为研究对象,比较储罐频率、液体等效质量、晃动波高等参数的不同.研究得到一些结论和建议,对修订我国储罐抗震设计规范有借鉴意义. 相似文献
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中外电气设备抗震设防标准对比分析 总被引：1，自引：1，他引：0
对比分析国内外电气设备的抗震设防标准,对提高我国电气设备的抗震能力和相关规范的修订具有十分重要的意义。在简要介绍目前美国、日本、IEC系列标准及我国电气设备相关规范的基本情况后,从抗震设防目标、设防水准、抗震设计反应谱等方面对比分析了电气设备抗震设防标准之间的差异,指出了我国相关规范的优缺点。通过借鉴国外电气设备抗震设防标准确定的经验,提出了改进我国电气设备抗震设防及规范修订的建议。 相似文献
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抗震设防标准是一个国家抗震设防水平的综合体现。文中在详细研究日本、印度、土耳其、中国等亚洲8个国家建筑抗震设计规范的基础上,从场地分类、地震影响系数和设计地震反应谱几方面进行分析对比,探讨了各个国家的抗震设防标准差异。结果表明:亚洲场地分类数目为3~4类,其中宏观描述为划分类别的主要指标之一;实例计算表明中国和日本的抗震设防水平较高,韩国和土耳其的抗震设防水平较低。亚洲大部分国家建筑抗震设计规范中考虑场地条件的影响是通过调整地震动强度及地震动反应谱形状的方式来实现。文中分析结果对系统了解亚洲国家抗震设防水平具有重要的参考价值。 相似文献
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抗震规范应用强度折减系数的现状及分析 总被引：5，自引：1，他引：4
世界上大多数的抗震规范都采用了基于强度的设计方法,强度折减系数是基于强度的抗震设计中确定设计地震力的关键因素,提高强度折减系数的可靠性已经被认为是提高现有抗震规范可靠性的有效途径。本文主要介绍了抗震研究处于世界先进水平的美国(UBC97)、欧洲(EC8)、日本、墨西哥、加拿大、中国等国家抗震规范中强度折减系数取值的有关规定,然后给出了各国学者关于规范规定的强度折减系数的一些重要讨论和分析,最后指出了世界各国应用强度折减系数过程中存在的不足,指出了需进一步研究的问题。 相似文献
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重点介绍美国IEEE Std 693-2005、IEC系列标准和我国电气设备抗震规范的基本情况后,从抗震设防目标、设防水准、场地类别、抗震设计反应谱、安装方式、抗震措施和抗震能力要求等方面对比分析了电气设备抗震设计技术的差异,指出我国规范中设计的不足。通过对比研究美欧先进的电气设备抗震设防标准,提出了改进我国电气设备抗震设计规范修订的建议。建议我国应适度提高电气设备抗震设防目标和设防水准、重新考虑阶梯跳跃变化的场地分类方案,修正设计反应谱的特征周期和反应谱值,以及提高我国电气设施抗震设计的措施等,提高我国电气设备的抗震能力。 相似文献
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《建筑工程抗震设防分类标准》（GB50223-2008）和《关于学校、医院等人员密集场所建设工程抗震设防要求确定原则的通知》（中震防发49号）从不同角度对学校和医院等乙类建筑的抗震设防提出要求。通过抗震设计中地震作用计算的原理以及国内外规范抗震设计的方法的阐述,讨论在不同抗震设防烈度下何种方法对乙类建筑结构抗震能力的提高更为有效,并通过对混凝土框架和钢框架的实例分析和验证,提出设计建议。为规范的修订完善提供参考。 相似文献
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2020年6月交通运输部发布了新版《公路桥梁抗震设计规范》（JTG/T 2231-01-2020）（简称"《公规》"）。本文比较了现行《铁路工程抗震设计规范》（GB 50111-2006）（2009年版）（以下简称"《铁规》"）与《公规》的抗震设计相关内容,并分别采用两本规范对25m墩高（D类）、35m墩高（C类）和40m墩高（B类）简支梁进行抗震设计,比较二者地震力和配筋设计结果差异。结果表明:《公规》和《铁规》的抗震设计框架和内容基本一致,在具体规定上如E2或罕遇地震设计最大加速度响应值以及桥墩强度和延性验算方法等方面不同;D类桥梁《铁规》地震力明显大于《公规》,C类和B类桥梁《铁规》和《公规》地震力相当;地震力相同时,《铁规》配筋率计算值大于《公规》,因《铁规》配筋设计基于容许应力法,而《公规》基于极限状态法。 相似文献
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采用对比方法介绍了中日建筑抗震规范设计标准在抗震设计思路、设防目标、设计方法及地震反应谱等方面的异同,由此阐述中日建筑抗震规范的各自特点以及对建筑物设计的影响,从而为工程抗震设计提供参考。 相似文献
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本文按现行规范及技术规程设计了设防烈度为8度的一个规则的钢筋混凝土异形柱框架,并进行了单向水平地震作用下的空间三维非线性地震反应分析,考查了异形柱框架结构在设防和罕遇地震水准下的整体抗震性能,对结构能否达到抗震设防目标进行了初步评价。结果表明,8度区按规范设计的结构在设防烈度及罕遇烈度地震作用下基本能够达到预期的抗震设防目标。 相似文献
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An important first step in marine spatial planning and ecosystem-based management efforts is the creation of benthic habitat maps that allow scientists and managers to understand the distribution of living and non-living resources on the seafloor. However, the location of boundaries between and composition of habitats is highly dependent on the approach taken to integrate abiotic and biotic information. The purpose of this study was to test “top-down” and “bottom-up” approaches for integrating physical and biological data derived from commonly used sub-tidal benthic mapping tools to create a habitat map compatible with the US Coastal and Marine Ecological Classification Standard (CMECS). We found that a top-down framework, where we tested for differences in macrofauna assemblages among side scan sonar facies, defined two broad-scale and general habitats. Using the bottom-up approach, where patterns in abiotic and biotic variables were examined with multivariate statistics (BEST, LINKTREE, ANOSIM, SIMPER), we generated seven biotopes based on the macrofauna abundance, percent sand, water depth, and backscatter standard deviation that corresponded well to, but provided more fine-scale detail than the top-down habitats. We were able to use the statistical relationship between abiotic variables and macrofauna assemblages in the LINKTREE to predict the spatial distribution of assemblages over ∼50% of the study area. We created a local catalogue of biotopes specific to our study area that contributes to the CMECS library. In addition, we were able to fully map CMECS Geoform, Surface Geology, and Biotic Cover Components. This mapping effort represented real progress toward reconciling the “data density mismatch” between physical and biological mapping methods, and it provided further evidence that using a bottom-up methodology preserves species–environment relationships. 相似文献
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Hydrological models have been widely applied in flood forecasting, water resource management and other environmental sciences. Most hydrological models calibrate and validate parameters with available records. However, the first step of hydrological simulation is always to quantitatively and objectively split samples for use in calibration and validation. In this paper, we have proposed a framework to address this issue through a combination of a hierarchical scheme through trial and error method, for systematic testing of hydrological models, and hypothesis testing to check the statistical significance of goodness-of-fit indices. That is, the framework evaluates the performance of a hydrological model using sample splitting for calibration and validation, and assesses the statistical significance of the Nash–Sutcliffe efficiency index (Ef), which is commonly used to assess the performance of hydrological models. The sample splitting scheme used is judged as acceptable if the Ef values exceed the threshold of hypothesis testing. According to the requirements of the hierarchical scheme for systematic testing of hydrological models, cross calibration and validation will help to increase the reliability of the splitting scheme, and reduce the effective range of sample sizes for both calibration and validation. It is illustrated that the threshold of Ef is dependent on the significance level, evaluation criteria (both regarded as the population), distribution type, and sample size. The performance rating of Ef is largely dependent on the evaluation criteria. Three types of distributions, which are based on an approximately standard normal distribution, a Chi square distribution, and a bootstrap method, are used to investigate their effects on the thresholds, with two commonly used significance levels. The highest threshold is from the bootstrap method, the middle one is from the approximately standard normal distribution, and the lowest is from the Chi square distribution. It was found that the smaller the sample size, the higher the threshold values are. Sample splitting was improved by providing more records. In addition, outliers with a large bias between the simulation and the observation can affect the sample values of Ef, and hence the output of the sample splitting scheme. Physical hydrology processes and the purpose of the model should be carefully considered when assessing outliers. The proposed framework in this paper cannot guarantee the best splitting scheme, but the results show the necessary conditions for splitting schemes to calibrate and validate hydrological models from a statistical point of view. 相似文献
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L. A. Molotkov Vlastislav Červený Oldřich Novotný Reviewer J. Vaněk 《Studia Geophysica et Geodaetica》1976,20(3):219-235
Summary Low-frequency and high-frequency expressions are derived for the reflection and transmission coefficients of SH waves on transition layers, in which the modulus of torsion and density vary with depth only. Both the expressions are exact for any finite frequencies. However, the use of the former formulae is more convenient for low frequencies and, likewise, the latter formulae for high frequencies. Explicit expressions for several first terms of the expansions in terms of and 1/ are given. 相似文献
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Characterization of and correction for cultural noise 总被引：2，自引：0，他引：2
Andreas Junge 《Surveys in Geophysics》1996,17(4):361-391
Surveys of time varying electromagnetic fields result in time series consisting of signals and noise, the latter defined as that part of the data which cannot be explained by a theory. Man-made contributions to noise can be subdivided into active and passive sources and are complex in character. As Szarka has treated this topic extensively in a recent review paper (Szarka, 1988), only a few further examples are presented here. Following discussion of noise correction in transient electromagnetic investigations which consists mainly of sophisticated stacking and filter procedures, several aspects of its correction in magnetotelluric and geomagnetic depth sounding data are considered. These include:
- The methods of treatment of single time series in the presence of visible noise—its detection, removal and sometimes replacement by data predicted from undisturbed intervals.
- The investigation of time series interrelations. This is mainly coherence based and—if possible—takes advantage of remote reference techniques.
- The examination of the statistical properties of the time series by regression analysis. This leads to the weighting of time segments of data in order to achieve unbiased and minimum variance estimates based on identically and independently Gaussian distributed residuals.
- The application of constraints. These can further improve the estimates' quality.
- The use of simultaneously recorded multistation data. This can contribute remarkably to noise suppression as well as to the treatment of non-uniform source fields.
- Leveraging and confidence limits. Problems relating to the former have not yet been solved satisfactorily while the Jacknife method seems to be an easy way of determining the latter.
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Following an overview of pertinent literature, this paper presents a new methodology for estimating seismic coefficients for the performance-based design of earth dams and tall embankments. The methodology is based on statistical regression of (decoupled) numerical data for 1084 potential sliding masses, originating from 110 non-linear seismic response analyses of 2D cross sections with height ranging from 20 to 120 m. At first, the methodology estimates the peak value of the seismic coefficient khmax as a function of: the peak ground acceleration at the free field, the predominant period of the seismic excitation, the non-linear fundamental period of dam vibration, the stiffness of the firm foundation soil or rock layer, as well as the geometrical characteristics and the location (upstream or downstream) of the potentially sliding mass. Then, it proceeds to the estimation of an effective value of the seismic coefficient khE, as a percentile of khmax, to be used with a requirement for pseudo-static factor of safety greater or equal to 1.0. The estimation of khE is based on allowable permanent down-slope deviatoric displacement and a conservative consideration of sliding block analysis. 相似文献
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震源性质的时频分析与事件识别 总被引：1，自引：1，他引：0
应用时频分析技术研究了近年来发生在朝鲜半岛的核爆炸、化学爆炸与天然地震事件的识别问题,计算了上述三者的瞬时频率、瞬时振幅谱与群延迟等多项参数,提出地震与爆炸的识别指标.初步研究结果表明,对较大事件,上述三者来自震源的激发频率信息有明显差异性,核爆炸源激发的频率明显高于地震,化学爆炸最低.特别是,这些信息指标对于识别小当... 相似文献
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科技期刊发展的挑战与机遇 总被引：3，自引：0，他引：3
中国加入世贸组织后 ,面对开放的世界性大市场的直接冲击 ,我国出版发行行业的竞争必将更加激烈。优胜劣汰 ,会直接考验每个出版社、每份期刊。为了使我国的期刊在竞争中成为胜者 ,探讨了科技期刊参与竞争的困难与优势 ,提出了如何提高我国科技期刊竞争力的粗浅看法 相似文献
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地震海啸监测预警现状与进展 总被引：3，自引：2，他引：1
2004年12月26日印度洋地震大海啸引起了全世界公众的关注和政府的重视,如何预防地震海啸造成的灾害,建立有效的预警机制,成为政府和社会关注的话题。介绍了国内外地震海啸监测预警的历史、现状与当前的发展方向。 相似文献