再生混凝土梁抗弯理论与可靠度分析

基于国内外再生混凝土梁抗弯承载力的试验结果与采用<混凝土结构设计规范>(GB 50010-2002)计算结果的对比分析,从统计意义上表明<混凝土结构设计规范>同样适用于再生混凝土适筋梁.根据再生混凝土的受压本构关系,证实<混凝土结构设计规范>在再生混凝土正截面受弯承载力计算中的适用性;运用蒙特卡洛法对再生混凝土梁的抗弯承载力进行了可靠度分析.结果表明:可用<混凝土结构设计规范>计算再生混凝土梁抗弯承载力,且不需对其等效矩形压应力图形参数α1和β1进行修正;再生混凝土适筋梁的可靠度满足<建筑结构可靠度设计统一标准>(GB 50068-2001)要求;抗力不定性系数XP对再生混凝土梁抗弯承载力可靠度有影响,再生混凝土材料分项系数对适筋梁抗弯承载力可靠度指标影响不大.     

再生混凝土梁抗弯承载力的试验

对10根不同废弃骨料掺入量的再生混凝土梁进行了抗弯承载力试验,研究了再生混凝土梁正截面受力全过程和破坏形态.试验结果表明:再生混凝土梁与普通混凝土梁一样,正截面受弯破坏都需要经历弹性、开裂、屈服和破坏4个阶段;再生混凝土梁同样符合平截面假定.最后,根据GB50010-2002<混凝土结构设计规范>提出的普通混凝土梁的计算公式,验算了再生混凝土梁的极限承载力与普通混凝土梁极限承载力差别不大,可以用现行的公式计算.     

氯离子环境下混凝土结构耐久性设计方法

现阶段混凝土结构耐久性问题日益突出,成为影响工程结构服役寿命的重要因素,而目前在<混凝土结构设计规范>(GB50010-2002)中尚未明确提出具体的耐久性设计方法.针对这种情况,本文以氯离子环境作用为例,提出在氯离子环境作用下进行混凝土结构耐久性设计时应遵循的原则和方法.     

钢筋混凝土结构预埋件的计算与分析

由锚板和对称配置的直锚筋所组成的受力预埋件在现行<混凝土结构设计规范>(GB 50010-2002)中,只提供了锚筋的总截面面积As的计算公式和锚板厚度t的最小构造要求.实践证明:锚筋对锚板外的传力板边缘的弯矩是决定锚板厚度的重要因素.按现行<钢结构设计规范>(GB 50017-2003)在分析计算锚板厚度的基础上,提出可不再计算锚板厚度的构造要求.     

钢筋混凝土结构中美规范地震作用的对比

根据某火力发电厂结构设计的需要,应用通用有限元分析软件STAAD.PRO和混凝土结构设计软件PKPM对该电厂混凝土框架结构进行对比分析,地震作用分别采用美国抗震设计规范UBC97和中国抗震设计规范GB50011,得出了混凝土框架的柱脚力和杆件内力对比结果,分别对角柱、中间柱、边梁、中间梁内力对比结果进行了总结,对比报告满足了国外火力发电厂机组混凝土结构设计的要求,为国外工程混凝土结构的设计提供了有力依据。     

曲线钢-混凝土结合梁桥的混凝土收缩徐变效应计算

将混凝土的应变分解为瞬时应变、徐变和收缩应变三部分之和,基于CEB-FIP模型提出了模拟收缩徐变的简明本构模型.根据本构模型给出了收缩徐变产生的单元等效结点力增量计算式,并结合迭代法逐步计算原理给出了计算收缩徐变的有限元公式.最后,应用收缩徐变模型和对应的有限元计算理论编制程序计算了曲线钢-混凝土结合梁桥的收缩徐变效应,结果表明收缩徐变对曲线钢-混凝土结合梁桥的内力和变形均有很大的影响.     

高强混凝土立方体强度变异系数的商榷

对《混凝土结构设计规范》GB50010—2002所给变异系数的合理性进行了研究,发现规范所给变异系数偏大且过于粗略;在《混凝土结构设计规范》GBJ10—89的背景材料和清华大学叶列平等人的建议的基础上计算出了C50～C80级高强混凝土的标准差和变异系数,对结果存在的局部不合理进行了调整,并把调整后的结果和规范GB50010—2002所给变异系数以及几个工程实例的统计参数进行了比较,发现调整后的结果与工程实际统计数据比较接近,用于高强混凝土结构可靠度分析、高强混凝土某些强度指标的确定以及施工过程中高强混凝土配合比强度的确定时,比规范GB50010—2002所给变异系数要更适合.     

钢筋混凝土简支梁破坏过程数值分析

利用ANSYS模拟钢筋混凝土2根简支梁破坏过程,并利用ANSYS的后处理程序绘出荷载-位移和弯矩-位移曲线,根据荷载-位移和弯矩-位移曲线分析简支梁的不同的破坏形式,给出极限弯矩和抗剪承载力,与混凝土结构设计规范(GB50010-2002)计算的结果比较,分析了2种计算结果差异的原因.     

型钢混凝土(SRC)梁受弯承载力计算方法比较

根据已有的资料,对<钢骨混凝土结构设计规程>和<型钢混凝土组合结构设计规程>规定的关于型钢混凝土梁受弯承载力计算公式进行比较分析,得出结论,并提出了现阶段存在的主要问题,最后提出一些适合工程应用的建议.     

现浇钢筋砼楼板裂缝的成因及处理

分析了现浇钢筋砼楼板产生裂缝的多种原因,阐述了楼板转角处45°斜裂缝的成因,指出避免这种裂缝应按《混凝土结构设计规范》(GBJ50010-2002)的有关要求设计制造楼板,介绍了裂缝处理的各种方法.     

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.     

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.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.