基于中国规范的剪力墙构件性能指标限值初探     

劳晓春  韩小雷  黄超 《地震工程与工程振动》2010,30(4)

本文主要论述了基于中国规范的剪力墙构件性能指标限值的研究思路和方法。首先根据规范的相关震害概念,提出小震、中震、大震三种地震水准下剪力墙构件的基本性能要求,然后通过对剪力墙构件的破坏形态及其影响因素的分析,给出剪力墙构件的分类及其性能指标限值的确定方法,并讨论了对结构中的剪力墙进行构件划分的方法,最后对剪力墙构件性能指标限值合理性的检验进行了论述。  相似文献   

基于核主成分元胞模型的城市演化重建与预测   总被引：3，自引：1，他引：2  

冯永玖  刘妙龙  童小华  刘艳  韩震 《地理学报》2010,65(6):665-675

通过元胞自动机(CA)模拟和重建城市演化的复杂非线性过程,对于城市土地利用规划和决策具有指导意义。利用传统线性方法获取的地理CA转换规则,较难刻画城市演化的时空动力学过程。基于核主成分分析方法(KPCA),通过核函数映射,在高维特征空间下不仅能够对多重共线的空间变量进行非线性降维,且由此建立的地理元胞模型KPCA-CA参数物理意义明确,能够较好地体现城市化过程的非线性本质。基于GIS环境下自主研发的地理模拟框架SimUrban,利用该KPCA-CA模型模拟和重建了快速城市化区域上海市嘉定区1989-2006年城市演化过程,并预测了研究区2010年的城市空间格局。模拟结果显示,嘉定区城市主要沿中心区域及主干道路而扩展,体现了KPCA方法提取的前两个主成分的作用,与城市实际发展情况相符。利用混淆矩阵和面积控制精度等指标,对模拟结果进行了评价,得到总体精度为80.67%、Kappa系数为61.02%,表明模拟结果与遥感分类结果及统计结果符合程度较好;与传统基于线性方法的地理CA模型比较,KPCA-CA模型模拟结果精度更高。  相似文献   

Seismic response of nonstructural components attached on multistorey buildings          下载免费PDF全文

Stylianos I. Pardalopoulos  Stavroula J. Pantazopoulou 《地震工程与结构动力学》2015,44(1):139-158

The maintenance of integrity and functionality of nonstructural components during earthquake excitations is of paramount importance since mechanical failure of those systems can have dramatic consequences in terms of property damage and life safety of the buildings' occupants. This paper explores the dynamic response of nonstructural elements attached on multistory buildings with well‐established floor diaphragm action. Depending on the type of support conditions, seismic response of nonstructural components may be controlled either by acceleration or displacement: Nonstructural components that are subjected to uniform support excitation are controlled primarily by the absolute spectral acceleration developing at their point of attachment on the supporting building. On the contrary, seismic response of multiply supported nonstructural components depends primarily on the relative displacements between successive support points that are imposed by the supporting building during lateral sway. These findings are illustrated from the analytical formulation and its solution through time history analysis of the governing dynamic equation of motion of the primary and secondary components of a system modeled using finite elements. The model encompasses the assembly of a multistory building along with a multiply supported gas pipeline network. It is shown that the dependence of the seismic response of nonstructural components may be linked to the deformed shape of the supporting building at the state of its maximum lateral roof displacement, thereby enabling the definition of design procedures for these systems. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

细粒浊积岩特征、分布及发育机制:以川北唐家河剖面寒武系郭家坝组为例^*     

龚峤林  李飞  苏成鹏  曾楷  唐浩  谭秀成 《古地理学报》2018,20(3):349-364

细粒浊积岩是一类较为特殊的浊积岩类型,与可用鲍马序列解释的完整经典浊积岩相比,其颗粒粒径明显偏细,小于63μm的颗粒含量超过50%。通过对四川盆地北部唐家河剖面寒武系第二统郭家坝组上部地层的系统研究发现,Stow细粒浊积岩序列发育广泛。该序列下部(T0-T3)主要为极细砂、粉砂与泥质纹层互层,发育微弱冲刷构造和泄水构造等软沉积物变形构造;中部(T4-T6)为泥质层段夹断续粉砂质纹层;上部(T7-T8)转变为均质泥岩段,生物扰动构造发育,整体序列具有正粒序特征。浊积岩序列中碎屑颗粒主要为石英、岩屑和云母,长石少见,杂基含量高;粒度频率分布曲线(直方图)显示颗粒分选性比传统浊积岩好,且自下而上各砂质纹层内颗粒粒径变细;概率值累计曲线表现为“一段式”和“上凸的折线式”2种,且悬浮组分占据了绝大优势;C-M图以平行于“C=M”基线为特征,但受碎屑颗粒粒级偏小的影响,投点整体沿C=M基线向左下偏移,显示该序列具有浊流递变悬浮沉积的特点。结合筇竹寺阶(第二统)沉积背景,认为靠近研究区西北侧的摩天岭古陆为浊积岩发育的主要物源区,台内地形的遮挡为细粒浊积岩的发育提供了良好的地形条件,悬浮搬运和阵发性环境事件(如风暴、洪水等)搬运为细粒沉积物主要的搬运机制。以唐家河剖面为代表的寒武系郭家坝组细粒浊积岩的广泛发育,对于认识四川盆地北缘古地理格局和非常规油气勘探具有重要意义。  相似文献   

Elastic reverse time migration based on vector wavefield decomposition     

GONG Qiming  HAN Liguo  ZHOU Jinju 《世界地质(英文版)》2017,20(3)

Prestack elastic reverse time migration ( RTM) requires multicomponent seismic data .But for multi-component elastic Kirchhoff migration , there is a limitation that ray theory no longer applies if thegeology be-comes complicated .In this paper, the authors have created a new 2D migration context for isotropic , elastic RTM, which included decomposition of the elastic source and receiver wavefields into P and S wave vectors by decoupled elastodynamic extrapolation , which retained the same stress and particle velocity components as the input data .Then we appliedsource-normalized crosscorrelation imaging condition in elastic reverse time migra-tion to compensate the energy of deep strata .We found that the resulting images were nearly identical to the ve-locity model , and the resolution has been improved .Our method is a wavefielddecomposition based on vector , and we can alsoavoid the problem of polarity reversal of converted shear wave imaging .It proved the applicabili-ty of the method proposed in our paper .  相似文献   

Biomass allocation patterns of alpine grassland species and functional groups along a precipitation gradient on the Northern Tibetan Plateau   总被引：1，自引：1，他引：0  

Jian-shuang Wu  Zhen-xi Shen  Xian-zhou Zhang  Pei-li Shi 《山地科学学报》2013,10(6):1097-1108

Variations in the fractions of biomass allocated to functional components are widely considered as plant responses to resource availability for grassland plants. Observations indicated shoots isometrically relates to roots at the community level but allometrically at the species level in Tibetan alpine grasslands. These differences may result from the specific complementarity of functional groups between functional components, such as leaf, root, stem and reproductive organ. To test the component complementary responses to regional moisture variation, we conducted a multi-site transect survey to measure plant individual size and component biomass fractions of common species belonging to the functional groups： forbs, grasses, legumes and sedges on the Northern Tibetan Plateau in peak growing season in 2010. Along the mean annual precipitation （MAP） gradient, we sampled 7o species, in which 2o are in alpine meadows, 20 in alpine steppes, 15 in alpine desert-steppes and 15 in alpine deserts, respectively. Our results showed that the size of alpine plants is small with individual biomass mostly lower than 1.0 g. Plants keep relative conservative component individual responses moisture functional fractions across alpine grasslands at the level. However, the complementary between functional components to variations specifically differ among groups. These results indicate that functional group diversity may be an effective tool for scaling biomass allocation patterns from individual up to community level. Therefore, it is necessary andvaluable to perform intensive and systematic studies on identification and differentiation the influences of compositional changes in functional groups on ecosystem primary services and processes.  相似文献   

A novel decomposition of the quadratic transfer function (QTF) for the time-domain simulation of non-linear wave forces on floating bodies     

《Applied Ocean Research》2017

In the present study, a novel method is proposed for the separation of the second-order sum- and difference-frequency wave forces—that is, quadratic transfer functions (QTFs)—on a floating body into three components due to wave–wave, wave–motion, and motion–motion action. By applying the new QTF components, the second-order wave forces on a floating body can be strictly computed in the time domain. In this work, the boundary value problems (BVPs) corresponding to the three kinds of QTF components were derived, and non-homogeneous boundary conditions on the free surface and the body surface were obtained. The second-order diffraction potentials were determined using the boundary integral equation method. In the solution procedure, the highly oscillatory and slowly converging integral on the free surface was evaluated in an accurate and effective manner. Furthermore, the application of the QTF components in the time domain was demonstrated. The second-order exciting forces in the time domain were divided into three parts. Each part of these forces was computed via a two-term Volterra series model based on the incident waves, the first-order motion response, and the QTF components. This method was applied to several numerical examples. The results demonstrated that this decomposition yields satisfactory results.  相似文献   

可口革囊星虫Phasolosma esculenta体腔液的抗菌活性研究   总被引：2，自引：0，他引：2  

梁倩蓉  于曙光  刘顺  王国良  郑晓叶  彭雪美惠  周素明 《海洋学研究》2015,33(2):70-75

可口革囊星虫Phasolosma esculenta为我国特有的一种可食用海洋经济动物。本文以可口革囊星虫为研究对象,利用琼脂径向扩散、涂板计数等方法研究其体腔液中物质的抗菌活性以及理化特性。研究结果表明,可口革囊星虫体腔液中存在抗菌活性物质,并且该物质对金黄色葡萄球菌Staphylococcus aureus等3种革兰氏阳性细菌具有明显的抗菌效果,但对大肠杆菌Escherichia coli等3种革兰氏阴性细菌以及葡萄牙假丝酵母Candida lusitaniae抗菌效果不明显。结果还发现:(1)不同提取方式出现明显不同的抗菌效果,与体腔液上清液和2%乙酸提取体腔液所得提取物的抗菌效果相比,超声破碎处理提取物的抗菌效果最为明显。(2)理化特性研究发现该抗菌物质抗菌效力持久,抗冻融,并且在5~30 ℃范围内最适抗菌温度约为25 ℃;该物质不耐高温,60 ℃处理10 min后该物质的抗菌作用完全消失;此外,该物质的抗菌作用不依赖金属离子的存在。(3)超滤管过滤截留琼脂扩散结果表明该抗菌物质的分子量在100 kDa以上。  相似文献   

新疆阜康断裂带中段大黄山探槽晚第四纪沉积物的光释光测年     

戴训也  沈军  吴传勇  杨会丽 《地震地质》2014,36(4)

对新疆阜康断裂带中段大黄山探槽的23个样品进行了细颗粒石英光释光简单多片再生法测年。样品LED12-297等效剂量的预热坪实验结果表明,在220~260℃的预热温度范围内均能获得基本一致的等效剂量值。测年结果显示,样品年龄与地层的时序性一致,表明阜康断裂带为全新世活动断层。根据探槽剖面错断的最新地层及其上覆地层的光释光年龄判断,断层的最新1次古地震事件发生在距今(1.90±0.14)ka~(3.47±0.17)ka。根据地层的垂直位移量与测年结果得到,阜康断层大黄山段的垂直滑动速率为0.17mm/a。  相似文献   

三江平原季节性积水沼泽湿地能量平衡要素研究     

李科  王毅勇  王瑗 《湿地科学》2008,6(2)

2005年6月1日到8月30日,在中国科学院三江平原沼泽湿地生态试验站沼泽综合试验场季节性积水沼泽湿地,观测了净辐射和土壤热通量;利用Penman-Monteith公式和地表能量平衡方程式计算了潜热通量和感热通量;同时用SHAW模型对以上4个能量平衡要素进行了模拟研究,并用观测值以及模型效率、标准差和平均方差检验和评价了其模拟效果。结果表明,三江平原季节性积水沼泽湿地净辐射在6月末至7月初较大;潜热通量主要受净辐射的影响,与土壤水分关系不密切;沼泽湿地地表在6月初至8月中旬以吸收能量为主,8月末以后则开始释放能量;感热通量在植物生长季的初期和末期较大,在中期则比较小。SHAW模型能较好的模拟出沼泽湿地的净辐射、潜热通量和土壤热通量;该模型虽对感热通量的模拟结果并不理想,但能较好的模拟其变化趋势。这说明SHAW模型基本适用于对季节性浅积水沼泽湿地（水深小于10cm）能量平衡各要素的模拟。  相似文献