结构抗震性能评估的改进模态能力谱法

基于性能的抗震设计理论需要简便而合理的确定结构在地震作用下的弹塑性位移需求的方法.为了解决传统能力谱法在讨论结构弹塑性地震反应中采用等效高阻尼的不确定性和没有考虑高振型影响的局限性,提出基于多模态法和引入强度折减系数和延性系数修正弹性反应谱的改进的能力谱法的概念和实施步骤,并对框架结构进行了相应的抗震性能评估.算例分析表明,所提方法具有一定精度,且更为简便,在基于性能的抗震设计中具有一定的应用前景.     

钢筋混凝土核心筒基于位移的抗震设计方法研究

对于较重要的建筑结构,在基于性能抗震设计过程中,需要同时验算结构的抗震承载力和位移反应是否满足规范规定的限值.混凝土核心筒是我国超高层建筑中应用最为广泛的抗侧力单元,在承载力、刚度和延性方面均需进行详细的设计以满足更高的抗震要求.利用加速度反应谱和能力谱的基本原理,通过引入损伤指标及能力设计方法,本文提出一种混凝土核心筒基于位移的抗震设计方法,该方法可实现对目标位移和加速度(力)的双重控制,对结构进行更为合理的抗震设计.只要给定结构目标位移和目标加速度,即可利用该基于位移的方法进行抗震设计计算,得到混凝土核心筒在任一地震作用水平下的承载力和位移,同时,引入能力设计方法进行定量的构件构造措施设计,以保证构件在大震作用下具有足够的塑性变形能力.     

基于地震反应谱分析的全直桩码头结构优化

文章建立了参数化全直桩码头空间有限元模型,通过振型分解反应谱法分析了该结构在水平地震作用下的响应,在此基础上构建了合理的码头抗震优化设计数学模型,通过灵敏度分析和零阶算法进行求解,得到了满足抗震设计要求且单位面积码头所需材料最少的设计序列;同时探讨了不同位置底梁对于全直桩码头结构抗震性能的影响。仿真结果表明:采用整体布局优化和增设底梁相结合的方法对全直桩码头结构进行抗震优化设计是可行的;底梁布设可有效限制结构变形、减小桩基内力,从而提高结构的抗震性能。     

多水准位移能力谱抗震设计方法

在改进能力谱方法和多水准抗震设计理念的基础上,提出了基于位移能力谱的多水准抗震设计方法.利用位移能力谱方法,获得了结构在不同抗震设防水准下结构的位移需求和延性系数,并构造出多水准需求谱.从多水准需求谱上得到多个基于位移抗震设计的控制点,最终构造出结构设计能力基准曲线.基于结构设计能力基准线对结构进行设计,能使结构同时满足"小震不坏"的弹性位移需求和"中震可修"及"大震不倒"的弹塑性位移需求.根据一个单自由度桥墩抗震设计的全过程,说明了基于位移的多水准抗震设计方法不仅能够满足各个设防水准的需求,而且根据该方法设计的结构具有最优的经济性.     

大跨度斜拉桥的抗震概念设计

基于斜拉桥的基本动态性能的分析 ,结合地震位移反应谱和加速度反应谱 ,并利用飘浮体系简化分析模型 ,从结构体系的设计中 ,提出了斜拉桥的抗震概念设计方法 .考虑通过改善桥塔结构形式 ,有效地控制桥塔和桥墩承担的地震力和上部结构的地震位移 .并通过对某桥梁工程进行抗震分析 ,提出了立体桥塔的抗震设计方案 ,并验证了改进方案可以在很大程度上提高超大跨度斜拉桥的抗震性能     

考虑地震动不确定性的核电厂楼层反应谱分析

核电厂的楼层反应谱对评价核电结构和设备的抗震安全性具有重要意义.核电设计中一般采用确定性的方法计算楼层反应谱,实际上,地震的发生具有明显的随机性.根据我国地震影响区和厂址地震发生概率的特性分析,采用Monte Carlo概率统计方法,研究了地震动的不确定性对核电厂结构地震响应的影响.实际算例的计算结果表明,在满足90%保证率的前提下,考虑地震动不确定性计算的楼层反应谱将比按确定性方法计算的楼层反应谱在峰值频段有较大幅度的降低.研究结果将加深对核电设计保守性的了解.     

基于位移的结构抗震设计方法探讨

根据钢筋混凝土框架结构的受力特点,把其等效为单自由度体系,推导等效单自由度体系的等效参数,阐述了直接基于位移的抗震设计方法的思路.将结构的性能划分为功能完好、功能连续、破坏控制、损失控制及生命安全5个性能水平,并用层间位移角限值予以量化.通过实例分析表明,基于位移的抗震设计比基于强度的抗震设计更能有效地把握结构在未来地震作用下的行为,同时该方法能对不同的性能目标进行多目标设计,满足业主对不同抗震设防目标的要求.     

基于性能抗震分析的核电常规岛主厂房设计

为了对核电常规岛主厂房结构抗震进行分析,通过工程实例分析基于性能的抗震设计的优点,并在不同的抗震性能目标控制下,运用SAP2000有限元程序,对主厂房结构进行静力弹塑性分析,绘制能力谱-需求谱曲线,分析结构主要构件应力、应变和楼层层间位移角特点,检验结构的抗震性能。结果表明:主厂房结构应力、应变合理,层间位移角满足规范要求。该成果对基于性能的抗震设计方法的运用和推广具有一定的参考价值。     

汽轮机基础选型及结构抗震性能

为确定某核电汽轮机的基础形式以及明确其结构的抗震性能,本文通过LS-DYNA有限元程序建立了某汽轮机整体结构的三维有限元模型,就基础选型问题以及汽轮机整体的抗震性能进行了综合分析.结果表明:目前核电设备常选用的刚性基础和弹簧基础中,弹簧基础较刚性基础有更好的抗震性能,更适合作为该汽轮机的基础;采用弹簧基础作为该汽轮机的基础结构,在8度设防烈度多遇地震水准下,该汽轮机整体结构可以满足结构抗震要求,而在8度设防烈度罕遇地震水准下,该汽轮机部分结构变形过大且内力不满足自身强度要求及抗震要求,应加强相应结构的抗震性能.     

基于能力谱法导管架平台抗震性能评估

针对现行海洋平台抗震规范无法考虑平台结构弹塑性抗震性能及地震失效机制问题,提出基于能力谱法海洋平台抗震性能评估方法,获得平台结构抗震性能及失效模式,解决强震作用下海洋平台结构弹/塑性抗震评估技术难题。基于规范推荐地震弹性设计谱,采用折减系数建立弹/塑性反应谱,结合渤海某导管架平台,采用能力谱法进行弹/塑性抗震性能评估。结果表明:能力谱法计算简便,对于以第1阶振型为主导地震响应的平台结构具有较好的精度;采用能力谱法评估地震惯性载荷时须考虑其高度效应,可采用倒三角或高度等效加载方式;桩基失效是平台结构地震作用下主要失效模式,平台抗震设计时应保证桩腿具有足够强度和入泥深度,避免强震作用下桩基失效而导致平台结构整体倾覆。     

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.