高强钢外伸式端板节点性能试验与有限元分析

为了解高强钢端板连接节点的受力性能和失效机理,对Q690和Q960高强钢端板连接节点进行足尺模型试验研究和有限元模拟分析,并将试验结果与采用欧洲规范EC3的计算结果、有限元分析结果进行对比.研究结果表明:节点的失效模式为端板破坏和螺栓断裂;高强钢端板连接节点具有良好的转动能力;EC3中用于普通钢端板连接节点承载能力计算和失效模式预测的组件法可直接用于高强钢端板连接节点,但转动刚度的计算公式并不适用,且EC3关于保障节点转动能力的相关要求对高强钢端板连接节点偏于保守.本文建立的有限元模型可准确模拟该端板连接节点的弯矩-转角关系和失效模式.     

高强钢外伸式端板节点火灾性能试验与数值分析

对1个Q690和2个Q960高强钢外伸式端板连接节点进行高温550℃下的足尺模型试验研究和有限元模拟分析,并将试验结果与采用欧洲现行钢结构设计规范EN 1993-1-8的计算结果及有限元分析结果进行对比.结果表明,550℃时,Q690和Q960高强钢端板连接节点的承载力分别为常温时的45%和46%,初始转动刚度为常温时的57%和65%,但转动能力分别为常温时的1.43倍和1.66倍.EN 1993-1-8中基于普通钢端板连接节点常温力学性能所提出的组件法可直接用于预测高强钢端板连接节点火灾下的失效模式和承载能力,但初始转动刚度的计算公式并不适用,且采用EN 1993-1-8关于保障节点转动能力的相关要求对高强钢端板连接节点进行抗火设计偏于保守.有限元模型可准确模拟该端板连接节点火灾下的弯矩转角关系和失效模式.     

高强平齐式端板连接火灾下性能试验

采用稳态火灾试验方法,对7个梁柱平齐式端板连接节点在550℃的火灾高温下开展足尺试验研究,得到此类节点在火灾下的受力性能以及失效机理.节点试件包括4个高强钢端板连接节点和3个普通钢端板连接节点,所研究参数为端板材料和端板厚度.为对比分析,同时对上述7个节点试件在常温下的相应力学性能进行试验研究.此外,将试验结果同现行欧洲钢结构设计规范Eurocode3中相应条文进行对比分析.研究表明,无论在常温下还是在火灾高温下,同普通钢端板连接节点相比,采用相对较薄的高强钢端板可在提高节点转动能力的同时不影响其抗弯承载力,从而确保结构整体的安全性能.     

高强钢端板连接节点火灾下性能试验与理论研究

采用稳态火灾试验方法,对7个梁柱平齐式端板连接节点在550 ℃的火灾高温下开展足尺试验研究,得到此类节点在火灾下的受力性能以及失效机理.节点试件包括4个高强钢端板连接节点和3个普通钢端板连接节点,所研究参数为端板材料和端板厚度.为对比分析,同时对上述7个节点试件在常温下的相应力学性能进行试验研究.此外,将试验结果同现行欧洲钢结构设计规范Eurocode3中相应条文进行对比分析.研究表明,无论在常温下还是在火灾高温下,同普通钢端板连接节点相比,采用相对较薄的高强钢端板可在提高节点转动能力的同时不影响其抗弯承载力,从而确保结构整体的安全性能.     

波纹腹板H型钢梁柱端板螺栓连接节点抗弯性能

提出了一种波纹腹板H型钢梁与普通H型钢柱采用端板螺栓连接的节点构造.基于高强螺栓抗拉性能的刚性端板模型和T形连接件理论,提出波纹腹板H型钢梁柱端板螺栓连接节点的设计方法.进行了2个波纹腹板H型钢梁柱端板螺栓连接节点的静力试验,并使用商用有限元分析软件ABAQUS建立节点的有限元模型,将设计弯矩下的高强螺栓最大拉力的试验结果与有限元计算结果进行对比,证明了高强螺栓拉力计算公式的可靠性;通过对比设计弯矩和有限元计算的端板屈服弯矩,证明了端板厚度计算公式的合理性.     

全高强钢端板节点火灾后性能试验

为了解Q690高强钢端板节点火灾后的受力性能和失效机理,对2个过火550℃冷却后的Q690高强钢端板节点进行足尺模型试验研究,并将试验结果与常温下高强钢端板节点试验的结果、采用欧洲规范EC3计算的结果进行对比.研究结果表明:节点火灾后的失效模式为端板和螺栓组合破坏;高强钢端板节点火灾后仍具有良好的转动能力;EC3中用于普通钢端板节点承载能力计算和失效模式预测的组件法可直接用于计算和预测高强钢端板节点火灾后的承载能力和失效模式,但转动刚度的计算公式并不适用;过火550°C后冷却至常温,节点可恢复常温下90%以上的承载力.最后,给出判断高强钢节点火灾后失效模式的计算公式.     

高强钢端板连接节点弯矩-转角曲线数学模型

为预测高强钢端板连接节点在常温、火灾下及火灾后的弯矩-转角曲线,以四参数指数模型为基础,基于组件法和等效T型连接,提出了初始刚度、屈服后刚度和抗弯极限承载力的计算方法,将计算结果代入四参数指数模型得到预测高强钢端板连接节点弯矩-转角曲线的方法;与足尺试验中Q690和Q960高强钢端板连接节点在常温、火灾下及火灾后的共10组试验结果进行对比。结果表明,抗弯极限承载力的计算结果与试验值较吻合,其中Q960的相对误差在5%以内,初始刚度的计算结果比欧洲钢结构设计规范(EN 1993—1-8)的结果更接近试验值,预测的Q960高强钢端板连接节点弯矩-转角曲线与试验结果吻合,而Q690预测结果偏于安全。     

高强钢平齐式端板连接节点火灾后性能数值研究

采用Abaqus软件对高强钢平齐式端板连接节点火灾后性能进行模拟,结果表明有限元模型能准确模拟节点的弯矩-转角关系、节点失效模式和应力分布等.在此基础上,对端板采用Q460高强钢和Q345普通钢的节点进行参数分析.结果表明:在历经550℃火灾高温并冷却后,节点力学性能未发生明显退化;端板材料对节点初始刚度无影响,但对节点承载力影响显著;与采用较厚普通钢端板的节点相比,采用较薄高强钢端板的节点可实现相近的承载力甚至更高的转动能力.     

高强钢平齐式端板连接节点火灾后力学性能试验研究

火灾后,钢构件残余应力和变形的重新分布,导致钢结构整体在火灾后可能比火灾高温作用下更加危险.节点对钢结构整体安全性至关重要,为研究高强钢平齐式端板连接节点火灾后的力学性能,采用稳态试验方法对经历550℃的火灾高温并冷却至常温的7个端板连接节点进行试验,得到节点火灾后的变形状态、弯矩-转角关系曲线以及失效模式等.同时,将试验结果与普通钢端板连接节点过火后的力学性能进行对比分析.此外,将试验结果同现行欧洲钢结构设计规范Eurocode3中相应条文进行比较.研究表明:通过合理的节点设计,与采用较厚普通钢端板的节点相比,采用较薄高强钢端板的节点可实现相同的节点失效模式、相近的剩余承载力以及更高的(至少是相当的)节点转动能力;同时,欧洲钢结构规范Eurocode3中有关节点塑性抗弯承载力的条文适用于高强钢平齐式端板连接节点火灾后塑性抗弯承载力的预测.     

火灾下高强钢端板连接节点力学性能有限元分析

为研究高强钢端板连接节点在火灾作用下的力学性能,对7个梁柱端板连接节点在550℃的火灾高温下进行足尺试验研究.依据试验结果,采用通用有限元件ABAQUS建立高强钢端板连接节点有限元模型,从网格划分、单元种类选择、接触定义、分析步设置以及失效准则的确定等方面详细介绍建立模型过程,并得到高强钢端板连接节点在火灾下和常温下的弯矩-转角关系曲线、破坏模式以及端板的应力分布和屈服线模式.同时,将有限元分析结果同试验研究结果进行对比校验,结果显示,该有限元模型具有足够精确性.     

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).     

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.     

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.