树状结构空间四分叉铸钢节点抗弯极限承载力分析

用ANSYS有限元分析方法分析了树状结构空间四分叉铸钢节点在弯矩作用下的塑性区扩展过程及几何因素对抗弯极限承载力的影响,并在此基础上拟合出该类节点的抗弯极限承载力公式.结果表明:在弯矩作用下,节点首先在相邻分管相交界限处进入塑性,此后分管受拉较大一侧靠近节点核心区的部位进入塑性,两处塑性区随荷载增大而扩展,最终相互连接,节点核心区屈服,达到承载力极限;主分管之间夹角对节点抗弯极限承载力的影响不大,但主管径厚比对节点抗弯极限承载力的影响较大;节点承载力随分管与主管壁厚比的增大呈近乎线性增大;节点抗弯极限承载力随分管与主管外径比的增大而增大;承载力随主分管倒角半径的增大而增大,随分管外壁倒角半径的增大而增大,随分管内壁倒角半径的增大而先增大后减小.     

K型足尺相贯节点极限承载力试验研究

本文对K型节点支管在轴力、平面内弯矩、平面外弯矩共同作用下的极限承载力进行试验研究,分析节点加载过程中应力发展过程及位移变化。结果表明:通过对支管施加偏心荷载能够有效地模拟节点承受轴力、平面内弯矩、平面外弯矩的共同作用,节点区主管的局部屈曲是K型相贯节点的破坏模式。采用Eurocode 3中K型节点的公式对支管承受轴力、平面内弯矩、平面外弯矩共同作用的K型节点进行验算是可行的,验算表明节点是安全的且偏保守。     

深水跨接管热应力计算及敏感性分析

深水跨接管在受热及边界约束作用下将产生内部结构应力.采用理论研究及ABAQUS有限元数值模拟方法,对深水跨接管进行受力分析.结果表明,深水跨接管受热时,中跨管受力沿轴向保持一致,截面上则服从正弦/余弦分布,整体表现为受到轴力和弯矩的联合作用,弯管处应力集中现象明显,受力较大.在此基础上对深水跨接管热应力的敏感性进行分析,进而说明,温度差、中跨段长度、中垂段长度均对深水跨接管的热应力值有重要影响.其中,中垂段长度对跨接管中跨管轴力、弯矩影响权重最大.     

斜拉桥异型钢结构主塔力学特性影响因素分析

研究了斜拉桥异型钢结构主塔力学特性的影响因素.以安徽涡河三桥为工程实例,通过数值分析得到了主塔钢结构部分和塔根的弯矩、轴力和应力以及主塔最大位移随恒载、主塔高度、塔根无索区长度的变化规律.结果表明,随着恒载及主塔高度的增加,钢结构部分和塔根的弯矩、轴力和压应力以及主塔的最大位移都呈增加的趋势;当恒载增加到1.4倍实际恒载时,钢结构出现局部屈服;主塔高度变化对钢结构部分和塔根的弯矩、轴力和压应力以及主塔刚度均有较明显的影响,因此需合理控制主塔的高度;塔根弯矩的增量比主塔钢结构部分更大;塔根无索区长度增加对主塔受力有利,但考虑到索距及施工的需要,无索区长度应该控制在合理范围内.     

框架结构-筏板基础-地基共同作用的数值分析

考虑框架结构、筏板基础和地基的共同作用,采用有限元分析模型,通过框架结构、筏板基础和地基之间在连接处的静力平衡和变形协调作用,形成共同作用分析方法,与非共同作用方法进行对比,分析框架结构柱轴力和弯矩的变化情况.有限元分析表明,在共同作用下,筏板基础发生“盆形”变形,框架结构应力重分布为角柱轴力增大,边柱和中柱轴力减小,柱的弯矩显著增大.共同作用下,不同厚度的筏板沉降量不同,厚度越大,筏板最大沉降量越小.     

钢梁-混凝土柱单剪板连接节点的抗震性能

对3个钢梁-混凝土柱单剪板连接节点进行低周反复荷载加载试验,探讨螺栓配置和锚筋数量对其破坏形态和极限承载力等受力性能的影响.结果表明:钢梁-混凝土柱单剪板连接节点具有良好的抗震性能,3个节点试件的位移延性系数为5.5～6.0,符合抗震设计的延性要求.在最大荷载时,3个试件的等效黏滞阻尼系数为0.32～0.37,耗能能力强.高强螺栓群的嵌固作用使得节点能承受一定的弯矩.设计钢梁-混凝土柱单剪板连接节点的预埋件时,忽略节点的约束弯矩将导致节点存在安全隐患,降低结构的抗震性能.因此设计锚筋时,应同时考虑弯矩、剪力和轴力的共同作用.     

杂填土地层深基坑微型桩-锚-撑组合支护体系受力特性原位试验

为深入研究杂填土地层深基坑桩-锚-撑组合支护体系受力特性,依托青岛市某深基坑工程开展微型桩-锚-撑原位试验,分析不同开挖工况下双排微型钢管桩桩身弯矩与预应力锚索轴力的演化规律,揭示该支护体系下前、后排桩的受力性状、预应力锚索应力分布特征,探讨邻近建筑物、基坑暴露时间及钢支撑拆除对该支护体系内力的影响。研究结果表明：1)在基坑开挖过程中,前排桩在受力中起主导作用;当开挖至基底时,桩身最大正、负弯矩极值呈现增大趋势,且极值点不断下移,开挖面以上桩身弯矩均呈正“S”型分布。2)开挖深度增加引起开挖面上、下1.0 m范围内桩身弯矩显著增大,前排桩桩身的反弯点分别位于钢支撑下方0.5 m、开挖面位置。3)在开挖过程中,锚索轴力沿埋深方向呈现减小趋势,锚固段前端1.5 m之后的轴力基本不变或呈微小波动。4)锚索锚固段应力高度集中在锚固段前端4.0 m以内的区域,约为锚固段长度的44%,锚固段末端基本未产生轴力,可对该段长度进行优化处理。5)邻近建筑物对微型钢管桩桩身受力影响较小;随着基坑暴露时间增加,桩身弯矩呈微小增长趋势;钢支撑拆除后,前排桩的弯矩变化集中在0.38H～0.96H(H为基坑开挖深...     

方钢管混凝土X型节点受拉力学性能的非线性有限元分析

为研究主管轴力、内填混凝土对方钢管节点受拉力学性能的影响,文章进行了X型节点受拉的非线性有限元分析。以方钢管混凝土X型节点受拉试验为研究原型,改变主管的轴力比、宽厚比、支主管宽度比等参数,设计了12个方钢管混凝土和12个方钢管X型受拉节点试件,分别从节点承载力、抗拉刚度、支主管应力分布等方面进行了对比分析。结果表明:改变主管轴拉比、支主管宽度比及主管宽厚比,方钢管混凝土相对于方钢管的节点承载力提高均不显著;主管受轴压力作用时,方钢管混凝土节点承载力高于方钢管节点;方钢管混凝土节点的抗拉刚度、抗疲劳性能显著高于方钢管节点。     

板式铸钢节点静力性能试验研究

文章对新杭州火车东站无站台柱风雨棚板式铸钢节点进行了足尺模型试验和数值分析,研究了在4方向支管轴向力作用下的板式铸钢节点的受力性能。利用铸钢节点应力实测值对数值分析结果进行验证,据此判断铸钢节点内部应力分布;比较了中央有、无圆形雨水管2种铸钢节点的承载力差异,并选择屈服准则评估铸钢节点的承载安全性。试验结果表明:数值分析结果可信;中央雨水管对铸钢节点承载力影响较小;利用Von-Mises准则对铸钢进行节点承载安全性评估,铸钢节点有较高的强度储备。     

搭接N型方圆钢管节点极限承载力研究

对搭接N型方主管、圆支管的相贯节点进行了非线性有限元分析,揭示了平面N型搭接节点的受力性能,描述了搭接节点3个参数(支主管径宽比、主管宽厚比、支主管厚度比)的变化对节点极限承载力的影响,同时分析了主管荷载对节点极限承载力的影响,提出了影响系数.研究表明,主管承受轴力对节点极限承载力影响较大,规范公式未考虑主管轴力的影响,其计算结果与有限元计算结果和实验结果有一定的误差,有必要考虑主管应力对节点极限承载力的影响.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.