Error estimation of closed‐form solution for annual rate of structural collapse     

Brendon A. Bradley  Rajesh P. Dhakal 《地震工程与结构动力学》2008,37(15):1721-1737

With the increasing emphasis of performance‐based earthquake engineering in the engineering community, several investigations have been presented outlining simplified approaches suitable for performance‐based seismic design (PBSD). Central to most of these PBSD approaches is the use of closed‐form analytical solutions to the probabilistic integral equations representing the rate of exceedance of key performance measures. Situations where such closed‐form solutions are not appropriate primarily relate to the problem of extrapolation outside of the region in which parameters of the closed‐form solution are fit. This study presents a critical review of the closed‐form solution for the annual rate of structural collapse. The closed‐form solution requires the assumptions of lognormality of the collapse fragility and power model form of the ground motion hazard, of which the latter is more significant regarding the error of the closed‐form solution. Via a parametric study, the key variables contributing to the error between the closed‐form solution and solution via numerical integration are illustrated. As these key variables cannot be easily measured, it casts doubt on the use of such closed‐form solutions in future PBSD, especially considering the simple and efficient nature of using direct numerical integration to obtain the solution. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

A comparison of predictive methods in modelling the distribution of periglacial landforms in Finnish Lapland     

Mathieu Marmion  Jan Hjort  Wilfried Thuiller  Miska Luoto 《地球表面变化过程与地形》2008,33(14):2241-2254

This study compares the predictive accuracy of eight state‐of‐the‐art modelling techniques for 12 landforms types in a cold environment. The methods used are Random Forest (RF), Artificial Neural Networks (ANN), Generalized Boosting Methods (GBM), Generalized Linear Models (GLM), Generalized Additive Models (GAM), Multivariate Adaptive Regression Splines (MARS), Classification Tree Analysis (CTA) and Mixture Discriminant Analysis (MDA). The spatial distributions of 12 periglacial landforms types were recorded in sub‐Arctic landscape of northern Finland in 2032 grid squares at a resolution of 25 ha. First, three topographic variables were implemented into the eight modelling techniques (simple model), and then six other variables were added (three soil and three vegetation variables; complex model) to reflect the environmental conditions of each grid square. The predictive accuracy was measured by two methods: the area under the curve (AUC) of a receiver operating characteristic (ROC) plot, and the Kappa index (κ), based on spatially independent model evaluation data. The mean AUC values of the simple models varied between 0·709 and 0·796, whereas the AUC values of the complex model ranged from 0·725 to 0·825. For both simple and complex models GAM, GLM, ANN and GBM provided the highest predictive performances based on both AUC and κ values. The results encourage further applications of the novel modelling methods in geomorphology. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

双向单排配筋剪力墙节点抗震性能试验研究   总被引：3，自引：1，他引：2  

曹万林  孙超  杨兴民  张建伟  杨亚彬 《地震工程与工程振动》2008,28(3):104-109

双向单排配筋剪力墙结构适用于多层住宅结构。为了研究不同构造及不同连梁剪跨比的节点抗震性能,进行了5个连梁与墙肢节点的低周反复荷载试验。较系统地分析了其承载力、刚度及其退化过程、延性、耗能、破坏机制和破坏特征等。试验表明,经过合理设计,这种双向单排配筋剪力墙节点可以满足抗震要求。  相似文献   

附件一国家温室气体排放趋势及其履约进展     

向亮  高庆先 《气候变化研究进展》2008,4(06):382-388

对《联合国气候变化框架公约》秘书处最新公布的温室气体排放数据进行统计分析,结果显示：相对于基准年（1990年）,附件一国家温室气体排放总量整体呈下降趋势。其中,经济转型期国家温室气体排放总量总体上呈逐年下降趋势,非经济转型期国家的温室气体排放总量有逐年增长的趋势。美国和加拿大能源部门的温室气体排放量增长最为显著,相对于1990年,2005年其增幅分别为19.2%和28.6%;英国和德国能源部门温室气体减排量最为显著,其减幅分别为7.8%和17.4%。在2005年,有超过一半的附件一国家的实际排放量低于其目标排放量,履约进展状况良好。  相似文献   

Damage-based inelastic response spectra for seismic design incorporating performance considerations     

Yong Lu  Jianwu Wei 《Soil Dynamics and Earthquake Engineering》2008,28(7):536-549

Modern seismic design allows a structure to develop inelastic response during moderate to severe earthquakes. The emerging performance-based design requires more clearly defined levels of inelastic response, or damage, to be targeted for different earthquake hazard levels. While there are a range of factors that could influence the level of damage and hence the performance, the design strength remains to be a fundamental design parameter that is inherently related to the structural performance. In this paper, the response reduction factor, which is a normalized form of the design strength, is investigated on a direct damage basis. The implications of the damage-based strength reduction factor (SRF), denoted as R_D factor, on multiple performance targets are discussed. A series of R_D spectra are generated from a large set of ground motions in different groupings to examine the effects of local site condition, earthquake magnitude and distance to rupture on the R_D spectra. The overall mean and standard deviation of the R_D spectra for different levels of damage are obtained, and simple empirical formulas are proposed.  相似文献   

层次分析法（AHP）在尾矿库安全运行分析中的应用   总被引：9，自引：1，他引：8  

王涛  侯克鹏  郭振世  张成良 《岩土力学》2008,29(Z1):680-686

尾矿库是用于堆存金属非金属矿山进行矿石选别后排出尾矿的场所,是一种高势能的人造泥石流源,一旦发生事故将会严重威胁到库区周边环境和下游居民的生命及财产安全。考虑到我国小型尾矿库数量多、安全度水平低以及尾矿库发生事故的复杂性、多样性及不确定性等特点,根据影响尾矿库安全运行的因素建立层次结构模型,运用Delphi法构造相关因素的各层次判断矩阵,应用定性与定量相结合的层次分析法进行分析,最后确定出各影响因素的权重并进行总排序。结果表明,在尾矿库运行期间排洪系统对其整体安全影响最大,其次为筑坝堆存系统、尾矿库管理与维护、回水系统和尾矿输送系统。该研究结果可以为相关单位制定合理的安全防范措施提供必要的参考价值,从而有针对性的消除各种事故隐患,提高安全管理水平,确保尾矿库的安全运行。  相似文献   

北京高新技术产业区土地利用绩效综合评价   总被引：22，自引：0，他引：22  

班茂盛  方创琳  刘晓丽  刘海燕 《地理学报》2008,63(2):175-184

高新技术产业区是建设创新型城市的重要载体, 在实施国家自主创新战略中具有重要 作用。针对高新技术产业区土地利用评价中存在的问题, 引入了土地利用绩效的概念, 构建 了包括土地效益、土地利用效率和创新功能三个维度的高新技术产业区土地利用绩效理论模 型, 以这一模型为理论基础建立了由3 个二级指标, 8 个三级指标, 37 个四级指标组成的高 新技术产业区土地利用绩效综合评价指标体系, 同时以土地利用绩效概念模型为理论基础, 构造了与土地利用绩效指标体系相匹配的矢量评价模型。在此基础上, 以北京市高新技术产 业区中5 个不同类型的园区为例做了综合评价, 评价结果显示, 清华科技园、上地信息产业 基地以及中关村西区的土地利用绩效指数较高, 中关村软件园和永丰基地的土地利用绩效指 数较低。通过与其他评价模型的对比验证, 本文构造的评价模型对高新技术产业区创新能力 指数的变化更为敏感。  相似文献   

SIWR—Ⅱ水下机器人作业系统的研制   总被引：2，自引：0，他引：2  

王晓东  孟庆鑫 《海洋技术学报》1998,17(2):59-64

本文简要了ＳＩＷＲ－Ⅱ水下机器人作业系统的组成,详细说明了对接腕及旋转工具库的工作原理,介绍了系统的控制软件及可实现的功能  相似文献   

地质数据仓库设计中的几个问题   总被引：10，自引：2，他引：8  

胡光道 《地球科学》1999,24(5):522-524

提出并讨论了地质数据仓库系统设计中的几个问题：操作数据存储作 和数据仓库间的数据接口,借用地理信息系统来存储和表示空间数据,级联式更新、主题间复杂交系的表达,以及专用的数据抽取模型的设计。  相似文献   

固体不极化电极的研制及其应用效果   总被引：1，自引：0，他引：1  

陆阳泉  梁子斌  刘建毅 《物探与化探》1999,23(1):64-65,71

介绍固体不极化电极的技术指标、性能及其与国内外同类产品的比较和使用效果.  相似文献