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振戎中学食堂楼耗能减震分析与设计(Ⅱ)－能力谱法与地震损伤性能控制设计 总被引：1，自引：0，他引：1
本文针对云南洱源县振戎中学食堂钢筋混凝土耗能减振体系，首先建立了耗能减振结构构件的恢复力模型；其次，结合文献[10]提出的“三水准”地震损伤性能目标和文献[11]中的简化设计方法以及ATC-40报告中的能力谱法，对此结构在大震下的地震损伤性能进行了分析和设计验算；最后考察了耗能减振装置对结构损伤性能的控制效果。 相似文献
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本文针对云南洱源县振戎中学食堂钢钢筋混凝土耗能减振体系，首先建立了耗能减振结构构件的恢复力模型，其次，结合文献[10]提出的“三水准”地震损伤性能目标和文献[11]中的简化设计方法以及ＡＴＣ－４０报告中的能力谱法，对此结构在大震下的地震损伤性能进行了分析和设计验算，最后考察了耗能关振装置对结构损伤性能的控制效果。 相似文献
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钢筋混凝土耗能减振结构的地震损伤简化分析方法 总被引：1，自引：0，他引：1
本文提出了钢筋混凝土耗能减振结构地震反应和损伤分析的简化方法.首先给出了考虑轴力变化效应的耗能减振结构Pushoverr分析方法,以及结构等价阻尼比ζ的计算公式;其次,结合文献[12]中提出的"三水准"地震损伤性能目标,提出了耗能减振结构基于能力谱法的地震反应、损伤分析与性能设计方法;最后,对一座设置金属屈服型耗能器的四层钢筋混凝土框架结构进行了地震反应和损伤分析. 相似文献
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钢筋混凝土结构基于改进能力谱法的地震损伤性能设计 总被引：23，自引：8，他引：15
本文基于国内外非线性静力分析方法,阐述了最近由Ｃｈｏｐｒａ和Ｇｏｅｌ提供的改进能力谱法的基本概念和实施步骤;其次,结合文献「１８」中提出的钢筋沸凝土结构地震损伤“三水准”性能目标和改进能力谱法,提出了基于能力谱法的结构地震损伤性能简化设计及验算方法;最后,通过设计例题说明了本文方法的可行性,并将计算结果与时程分析进行了比较,显示了此法的有效性。 相似文献
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从基于性能的抗震设计理念出发,给出了客运专线桥梁结构的性能目标及各性能水准下的桥墩地震破损描述,明确并量化了桥墩各抗震性能目标的验算内容。给出了小震不坏及可控制中震损伤的验算方法,简化能力谱法计算位移延性系数,指出了大震时最大位移验算的不足,讨论了桥墩大震时地震损伤指数的计算与验算,通过算例详细介绍了基于性能的抗震设计方法与过程。 相似文献
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随着地震工程学的发展和结构抗震设计思想和理论的进步,探讨结构在地震作用下的地震损伤破坏机理和基于结构性能的抗震设计方法(PBSD)逐渐得到了各国专家、学者的重视。而地震损伤评估的研究就是其中的一个重要方向。鉴于现阶段混凝土结构地震损伤评估方法的局限性,本文采用推广的混凝土材料的Mazars损伤模型,进而提出了一种基于常规有限元分析荷载子步的简化的地震损伤评估方法,这种方法实现简单,便于实际工程应用,同时具有一定的精细性。最后,将本文的损伤评估方法应用到一个钢筋混凝土框架的地震损伤评估实例中,分析结果与实验和实际的震害比较吻合,表明本文提出的模型和方法是有效的。 相似文献
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钢筋混凝土结构的屈服位移Chopra能力谱损伤分析与性能设计 总被引：6，自引：0，他引：6
本文提出了应用地震损伤指数评定结构抗震性能要求的方法。首先，建立了抗力谱曲线和结构损伤指数的关系，得到了反映不同设防水准损伤目标的结构地震务容许延性系数；其次，应用屈服位移Chopra能力谱法确定地震损伤延性系数；然后，提出了应用结构地震损伤延性系数和容许延性系数之间的关系来评定结构抗震性能的方法；最后，通过算例说明了本文方法实施的步骤。 相似文献
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Gtz Schroth Luciana Ferreira Da Silva Marc‐Andree Wolf Wenceslau Geraldes Teixeira Wolfgang Zech 《水文研究》1999,13(10):1423-1436
The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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M. N. French R. L. Bras W. F. Krajewski 《Stochastic Environmental Research and Risk Assessment (SERRA)》1992,6(1):27-45
A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities. 相似文献
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M. A. Kahn 《洁净——土壤、空气、水》2000,28(2):95-101
Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate. 相似文献
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