大跨度钢桁架转换结构振动台试验研究   总被引：1，自引：0，他引：1  

刘劲松  裘涛  贺明卫 《世界地震工程》2006,22(4):145-149

以某带高位大跨钢桁架转换结构高层建筑为工程背景,进行了1/25缩尺比例的模型振动台试验,通过粘贴在钢桁架杆件上的应变片,测试了输入不同加速度峰值地震波作用下钢桁架的地震响应。在加速度峰值0.9g地震波作用下,两端支承钢桁架筒体剪力墙才出现裂缝,表明连接部位剪力墙受力性能较好;人工波作用下结构的地震响应最大,层地震作用力在钢桁架转换结构层有突变;试验中随模型结构裂缝发展和抗侧刚度衰减,层地震作用力分布发生变化,其中钢桁架转换结构层承担地震力相对减小,钢桁架应变反应也相对趋缓;钢桁架两端杆件受力较大,表明支承剪力墙对钢桁架的约束作用较大。  相似文献   

Mechanical compression release device in steel bracing system for retrofitting RC frames     

H. Ghaffarzadeh M.R. Maheri 《地震工程与工程振动(英文版)》2006,5(1):151-158

1 Introduction Braced steel frames are commonly used to resist seismic loads. Their seismic behavior was extensively studied during the past decades (Bertero et al.., 1989; Roeder, 1989; Jain, 1978). Their design is governed by the buckling behavior of the bracing members (ASCE, 1994,2002; CSA, 1994). To prevent or delay the seismic buckling of compressive members in concentrically braced frames in steel structures, a great number of methods have been proposed. These include the use of sp…  相似文献   

钢筋混凝土扁梁柱节点抗震设计方法   总被引：1，自引：0，他引：1  

戴益华 《地震工程与工程振动》2006,26(1):122-128

为考虑扁梁柱节点内、外核心区的相互作用,对扁梁柱节点的内、外核心区进行了重新划分,认为内、外核心区有一个重叠的区域,给出了地震作用在扁梁柱节点内外核心区的分配方法,采用压杆模型和软化桁架模型,提出扁梁柱节点的设计方法。该方法可以考虑节点核心区钢纤维和扁梁中无粘结预应力对扁梁柱节点抗剪极限承载力的作用。该设计方法的可靠性得到四个钢筋混凝土扁梁柱节点试验数据的验证。  相似文献   

型钢混凝土梁柱框支剪力墙结构抗震性能试验研究   总被引：3，自引：0，他引：3  

李国强  崔大光  李一松 《地震工程与工程振动》2006,26(2):80-87

框支剪力墙结构在实际工程中经常被采用,震害表明钢筋混凝土框支剪力墙结构抗震性能较差,本文提出型钢混凝土梁柱框支剪力墙结构对此加以改进。作者进行了4个1/4缩尺模型在竖向荷载和单调及低周反复水平荷载作用下的对比试验,其中3个试件采用型钢混凝土转换梁、型钢混凝土框支柱,1个试件采用钢筋混凝土转换梁、钢筋混凝土框支柱。我们分析其承载力、刚度、变形、延性和破坏形态等。试验结果表明,型钢混凝土梁柱框支剪力墙结构承载力高、延性好、滞回曲线丰满,变形能力和耗能能力较强。  相似文献   

Tangling Turbulence and Semi-Organized Structures in Convective Boundary Layers     

T. Elperin  N. Kleeorin  I. Rogachevskii  S. S. Zilitinkevich 《Boundary-Layer Meteorology》2006,119(3):449-472

A new mean-field theory of turbulent convection is developed based on the idea that only the small-scale region of the spectrum is considered as turbulence, whereas its large-scale part, including both regular and semi-organized motions, is treated as the mean flow. In the shear-free regime, this theory predicts the convective wind instability, which causes the formation of large-scale semi-organized motions in the form of cells. In the presence of wind shear, the theory predicts another type of instability, which causes the formation of large-scale semi-organized structures in the form of rolls and the generation of convective-shear waves propagating perpendicular to the convective rolls. The spatial characteristics of these structures, such as the minimum size of the growing perturbations and the size of perturbations with the maximum growth rate, are determined. This theory might be useful for understanding the origin of large-scale cells and rolls observed in the convective boundary layer and laboratory turbulent convection  相似文献   

台风"云娜"的热动力结构模拟试验研究     

程锐  叶成志  许爱华  尹珊建 《湖北气象》2007,26(2):103-108

对2004年8月登陆我国的台风"云娜"的热动力结构及其演变进行了数值模拟。试验从大尺度环境场、台风中尺度动力和热力场三维结构、台风云雨特征等多角度,对模拟结果与实际观测进行了对比。结果表明,模式不仅较准确地再现了台风登陆前24h移动和演变的全过程,在移向、移速和登陆时间、地点上与实况十分接近,而且对台风系统中尺度结构、云雨特征的模拟与分析场及卫星观测也有较好的一致性。采用的模拟工具是新开发的双重嵌套AREM模式,该模式是静力模式,但对台风仍有较强的模拟能力。此外,本试验无任何人为台风模型的嵌入是其中的一个特点,从而增加了试验的可信度。  相似文献   

Flux contribution of coherent structures and its implications for the exchange of energy and matter in a tall spruce canopy   总被引：2，自引：5，他引：2  

Christoph Thomas  Thomas Foken 《Boundary-Layer Meteorology》2007,123(2):317-337

The flux contribution of coherent structures to the total exchange of energy and matter is investigated in a spruce canopy of moderate density in heterogeneous, complex terrain. The study deploys two methods of analysis to estimate the coherent exchange: conditional averages in combination with wavelet analysis, and quadrant analysis. The data were obtained by high-frequency single-point measurements using sonic anemometers and gas analysers at five observation heights above and within the canopy and subcanopy, and represent a period of up to 2.5 months. The study mainly addresses the momentum transfer and exchange of sensible heat throughout the roughness sublayer, while results are provided for the exchange of carbon dioxide and water vapour above the canopy. The magnitude of the flux contribution of coherent structures largely depends on the method of analysis, and it is demonstrated that these differences are attributed to differences in the sampling strategy between the two methods. Despite the differences, relational properties such as sweep and ejection ratios and the variation of the flux contribution with height were in agreement for both methods. The sweep phase of coherent structures is the dominant process close to and within the canopy, whereas the ejections gain importance with increasing distance to the canopy. The efficiency of the coherent exchange in transporting scalars exceeds that for momentum by a factor of two. The occurrence of coherent structures results in a flux error less than 4% for the eddy-covariance method. Based on the physical processes identified from the analysis of the ejection and sweep phases along the vertical profile in the roughness sublayer, a classification scheme for the identification of exchange regimes is developed. This scheme allows one to estimate the region of the canopy participating in the exchange of energy and matter with the above-canopy air under varying environmental conditions.  相似文献   

二密铜矿控矿构造特征及找矿方向探讨     

张维山  刘振宇  刘东伟 《吉林地质》2007,26(1):5-9

二密铜矿位于二密中生代火山盆地中,矿床产于松顶山序列石英闪长岩与侏罗系火山岩接触带附近,矿体受多组断裂联合控制,矿体多呈脉状,主成矿期在花岗斑岩株侵入固结之后。成矿热液来源于深部,沿300°±断裂带及34°±断裂带运移至容矿构造中成矿。300°(4)与34°(6)两条主干断裂带交汇部位一带可能是主要成矿区。  相似文献   

Identification of tsunami deposits considering the tsunami waveform: An example of subaqueous tsunami deposits in Holocene shallow bay on southern Boso Peninsula, Central Japan     

Osamu Fujiwara  Takanobu Kamataki   《Sedimentary Geology》2007,200(3-4):295-313

This study proposes a tsunami depositional model based on observations of emerged Holocene tsunami deposits in outcrops located in eastern Japan. The model is also applicable to the identification of other deposits, such as those laid down by storms. The tsunami deposits described were formed in a small bay of 10–20-m water depth, and are mainly composed of sand and gravel. They show various sedimentary structures, including hummocky cross-stratification (HCS) and inverse and normal grading. Although, individually, the sedimentary structures are similar to those commonly found in storm deposits, the combination of vertical stacking in the tsunami deposits makes a unique pattern. This vertical stacking of internal structures is due to the waveform of the source tsunamis, reflecting: 1) extremely long wavelengths and wave period, and 2) temporal changes of wave sizes from the beginning to end of the tsunamis.

The tsunami deposits display many sub-layers with scoured and graded structures. Each sub-layer, especially in sandy facies, is characterized by HCS and inverse and normal grading that are the result of deposition from prolonged high-energy sediment flows. The vertical stack of sub-layers shows incremental deposition from the repeated sediment flows. Mud drapes cover the sub-layers and indicate the existence of flow-velocity stagnant stages between each sediment flow. Current reversals within the sub-layers indicate the repeated occurrence of the up- and return-flows.

The tsunami deposits are vertically divided into four depositional units, Tna to Tnd in ascending order, reflecting the temporal change of wave sizes in the tsunami wave trains. Unit Tna is relatively fine-grained and indicative of small tsunami waves during the early stage of the tsunami. Unit Tnb is a protruding coarse-grained and thickest-stratified division and is the result of a relatively large wave group during the middle stage of the tsunami. Unit Tnc is a fine alternation of thin sand sheets and mud drapes, deposited from waning waves during the later stage of the tsunami. Unit Tnd is deposited during the final stage of the tsunami and is composed mainly of suspension fallout. Cyclic build up of these sub-layers and depositional units cannot be explained by storm waves with short wave periods of several to ten seconds common in small bays.  相似文献   

松辽盆地北安地区断陷期构造特征的地震学证据及其油气意义          下载免费PDF全文

胡艳飞  于平  孔庆莹  王世煜 《地球物理学进展》2007,22(5):1455-1459

北安地区位于松辽盆地内的东北部,共有姚家组顶界、泉头组顶界、营城组顶界、基岩顶界四个主要地震反射层位,缺失登娄库组反射层.北安断陷期地层反射能量均较弱,且基本为中低频反射.北安断陷是北安地区最重要的一个断陷,北安断陷西侧发育有北安西断裂,走向北北东,在平面展布上近"S"型,主要发育于侏罗系地层;北安断陷东侧发育有北安东断裂,走向北北东,其特点是上逆下正,从姚家组断至侏罗系地层.北安地区发育有较大的正向反转构造.北安地区反转构造对油气成藏的影响较大,主要表现在:(1)反转构造为油气聚集提供了圈闭;(2)反转构造作用促进了油气再次运移;(3)反转构造作用使地层拱张,产生了许多断裂,改善了储集性能.  相似文献