Probability-consistent spectrum and code spectrum     

沈建文  石树中 《地震学报(英文版)》2004,17(1):99-108

IntroductionInChina,thecombinationofseismicdesigncodewithzoningmapofseismicintensityorgroundmotionparametersisusuallyadoptedtodeterminetheseismicfortificationcriterionforthegeneralindustryandcivilbuildings.Thepresentproceduresareasfollows.Accordingtothepro-jectlocation,thedesignbasicaccelerationofgroundmotionandthedesigncharacteristicperiodofresponsespectrumareobtainedfromthezoningmapofseismicgroundmotionparameters(GeneralAdministrationofQualitySupervision,InspectionandQuarantineofthePeople…  相似文献   

Period formulas of shear wall buildings with flexible bases     

Faouzi Ghrib  Haji Mamedov 《地震工程与结构动力学》2004,33(3):295-314

The evaluation of the fundamental period of shear wall buildings considering the flexibility of the base is investigated in this paper. This research is motivated by the discrepancy reported between the formulas used in different building codes and the measurement of real buildings. Both experimental and analytical approaches are used to assess the effect of the base flexibility on the fundamental period of shear wall structures. In total, twenty buildings built on different types of soil are tested under ambient vibration. The fundamental period is identified using a non‐parametric linear model in the frequency domain. The results show that fundamental period formulas used by UBC‐97 and NBCC‐95 are inadequate since they do not include the effect of the foundation stiffness. To improve the estimation of the fundamental period of shear wall buildings, an analytical approach is presented. The structure and the foundation are represented by a continuous‐discrete system. The stiffnesses of the base are represented by translational and rotational discrete springs. The rigidities of these springs are evaluated from the elastic uniform compression of the soil mass and the size of the foundation. The analytical predictions improve the estimation of the fundamental period and keep the computation simple. The error between the measured period and the analytical results is, on average, less than 10%. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Parameterization of the Absorption of the H_2O Continuum,CO_2,O_2,and Other Trace Gases in the Fu-Liou Solar Radiation Program     

张凤  曾庆存  K.N.LIOU 《大气科学进展》2005,(4)

The absorption properties of the water vapor continuum and a number of weak bands for H2O, O2, CO2, CO, N2O, CH4, and O3 in the solar spectrum are incorporated into the Fu-Liou radiation parameterization program by using the correlated k-distribution method (CKD) for the sorting of absorption lines. The overlap absorption of the H2O lines and the H2O continuum (2500-14500 cm-1) are treated by taking the two gases as a single-mixture gas in transmittance calculations. Furthermore, in order to optimize the computation efforts, CO2 and CH4 in the spectral region 2850-5250 cm-1 are taken as a new single-mixture gas as well. For overlap involving other absorption lines in the Fu-Liou spectral bands, the authors adopt the multiplication rule for transmittance computations under which the absorption spectra for two gases are assumed to be uncorrelated. Compared to the line-by-line (LBL) computation, it is shown that the errors in fluxes introduced by these two approaches within the context of the CKD method are small and less than 0.48% for the H2O line and continuum in the 2500-14500 cm-1 solar spectral region, -1% for H2O (line) H2O (continuum) CO2 CH4 in the spectral region 2850-5250 cm-1, and -1.5% for H2O (line) H2O (continuum) O2 in the 7700-14500 cm-1 spectral region. Analysis also demonstrates that the multiplication rule over a spectral interval as wide as 6800 cm-1 can produce acceptable errors with a maximum percentage value of about 2% in reference to the LBL calculation. Addition of the preceding gases increases the absorption of solar radiation under all sky conditions. For clear sky, the increase in instantaneous solar absorption is about 9%-13% (~12 W m~2) among which the H2O continuum produces the largest increase, while the contributions from O2 and CO2 rank second and third, respectively. In cloudy sky, the addition of absorption amounts to about 6-9 W m-2. The new, improved program with the incorporation of the preceding gases produces a smaller solar absorption in clouds due to the reduced solar flux reaching the cloud top.  相似文献   

Statistical Analysis on the Corner Period of Site-Related Design Spectra     

Wu Jian 《中国地震研究》2005,19(1):29-34

INTRODUCTIONFromTJ1 1 74 ,theseismicdesignforbuildingshasbeenbasedontheaccelerationresponsespectruminChina (HuYuxian ,1 988) .ThevalueofTgoftheresponsespectrumvariesbecauseofdifferentsiteclassesanddifferentearthquakeenvironments .Designresponsespectrainc…  相似文献   

地理网格技术在产地溯源码编制中的应用研究     

礼晟东  杨继文  朱道强 《测绘与空间地理信息》2016,(6)

针对农产品溯源中溯源编码通用性差、不便于查询的问题,本文分析了国内外地理网格技术与产地溯源码的研究现状,并结合二维码技术,提出了基于地理网格技术的二维产地溯源码编制规则,详细介绍了产地溯源编码的组成,并以应用实例验证了编码的实用性与便捷性。  相似文献   

基于GeoSOT剖分编码的不动产单元统一标识模型研究     

宋树华  董芳  陈东  赵金玲  李滨  张乐  王希营  李世忠  翟卫欣  孙忠秋 《测绘学报》2016,45(Z1):99-105

针对现有不动产单元编码存在空间位置信息模糊的问题,以寻求更加直接反映空间位置的不动产编码为目标,在对现有不动产单元编码深入研究的基础上,提出了基于GeoSOT网格编码的不动产单元模型、编码方法,以及该模型与空间位置信息转换方案。试验证明,基于GeoSOT的不动产单元编码更加直观,具有很好的实用性。  相似文献   

土工试验规范变更对膨胀计算和判定的影响     

刘军  石鹏飞  孙凯 《岩土工程技术》2021,(2):134-136,F0003

对土工试验方法标准的新旧规范中无荷膨胀率和有荷膨胀率的变化内容进行对比分析,发现两者的计算公式发生显著变化,新规范的计算结果与旧规范相比,膨胀率明显变大,膨胀量随之增大,这将对工程勘察、设计、施工等产生明显影响。以某工程为例,新规范计算后地层总膨胀量由旧规范的16.7 mm变为51.8 mm,增加了2倍左右,地基土的胀缩等级由Ⅰ级变为Ⅱ级,地基基础设计等级由丙级变为乙级,地基处理措施和施工方案随之也发生改变。因此,工程技术人员对此应综合考虑,严谨对待。  相似文献   

Modelling of groundwater flow in heterogeneous porous media by finite element method     

Hassan Smaoui  Lahcen Zouhri  Abdellatif Ouahsine  Erick Carlier 《水文研究》2012,26(4):558-569

The HySuf‐FEM code (Hydrodynamic of Subsurface Flow by Finite Element Method) is proposed in this article in order to estimate the spatial variability of the transmissivity values of the Berrechid aquifer (Morocco). The calibration of the model is based on the hydraulic head, hydraulic conductivity and recharge. Three numerical tests are used to validate the model and verify its convergence. The first test case consists in using the steady analytical solution of the Poisson equation. In the second, the model has been compared with the hydrogeological system which is characterized by an unconfined monolayer (isotropic layer) and computed by using PMWIN‐MODFLOW software. The third test case is based on the comparison between the results of HySuf‐FEM and the multiple cell balance method in the aquifer system with natural boundaries case. Good agreement between the Hydrodynamic of Subsurface Flow, the numerical tests and the spatial distribution of the thickening of the hydrogeological system is deduced from the analysis and the interpretations of hydrogeological wells. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

我国现行抗震设计规范中场地评定方法的比较和评述   总被引：1，自引：0，他引：1  

刘曾武  魏培恒 《地震工程与工程振动》1995,15(4):118-130

目前，我国抗震设计规范中采用的场地评定方法主要有两种：一是建筑抗震设计规范（ＧＢＪ１１－８９）采用的场地分类的方法，一是构筑物抗震设计规范（ＧＢ５０１９１－９３）和电力设施抗震设计规范采用的场地指数法。前者是把场地影响按照场地分类指标划分成若干场地类别，因此，确定的地震荷载是不连续的，跳跃变化的。后者是一种以模糊推论的综合评判方法导出的场地指数为指标进行连续评定的新方法，在这种方法里，场地性质的差  相似文献   

探讨渤海及周边地区海洋平台抗震设防水准   总被引：3，自引：0，他引：3       下载免费PDF全文

彭艳菊  吕悦军  唐荣余  沙海军 《地震学报》2005,27(6):647-655

介绍了美国API规范的内容，并将南加利福尼亚和中国渤海海域地震活动特征与地震危险性进行对比. 对比结果表明，无论在地震活动的频度与强度还是地震危险性分析结果上，渤海都比南加州弱. API规范指出，对于南加利福尼亚地区的永久性建筑， 强度设计水准取重现期200 a，变形设计水准取几百至几千年. 我国相关规范规定的海洋平台强度设计和变形设计水准分别取500 a和10 000 a，过于保守. 同时，与其它建构筑物的抗震水平相比较，甲类建筑变形设计水准取设计基准期100 a内超越概率2%~3%，乙、丙类取50 a内2%~3%，考虑海洋平台易于引起严重的次生灾害，变形设计水准取设计基准期30 a内1%（相当于重现期3 000 a）应是安全的. 基于上述对比分析， 同时考虑到经济承受能力以及与现行标准的连贯性， 建议我国海洋石油平台的强度设计水准和变形设计水准分别取200 a和3 000 a.   相似文献