Analysis and behaviour of FRP-confined short concrete columns subjected to eccentric loading     

Xing-fei Yuan  Shao-hua Xia  L. Lam  S. T. Smith 《浙江大学学报(A卷英文版)》2008,9(1):38-49

Fibre-reinforced polymer （FRP） composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete （RC） columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short columns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design.  相似文献   

An artificial neural network approach for prediction of long-term strength properties of steel fiber reinforced concrete containing fly ash     

Okan Karahan  Harun Tanyildizi  Cengiz D. Atis 《浙江大学学报(A卷英文版)》2008,9(11):1514-1523

In this study, an artificial neural network （ANN） model for studying the strength properties of steel fiber reinforced concrete （SFRC） containing fly ash was devised. The mixtures were prepared with 0 wt%, 15 wt%, and 30 wt% of fly ash, at 0 vol.%, 0.5 vol.%, 1.0 vol.% and 1.5 vol.% of fiber, respectively. After being cured under the standard conditions for 7, 28, 90 and 365 d, the specimens of each mixture were tested to determine the corresponding compressive and flexural strengths. The pa- rameters such as the amounts of cement, fly ash replacement, sand, gravel, steel fiber, and the age of samples were selected as input variables, while the compressive and flexural strengths of the concrete were chosen as the output variables. The back propagation learning algorithm with three different variants, namely the Levenberg-Marquardt （LM）, scaled conjugate gradient （SCG） and Fletcher-Powell conjugate gradient （CGF） algorithms were used in the network so that the best approach can be found. The results obtained from the model and the experiments were compared, and it was found that the suitable algorithm is the LM algorithm. Furthermore, the analysis of variance （ANOVA） method was used to determine how importantly the experimental parameters affect the strength of these mixtures.  相似文献   

政府公共政策执行力弱化的原因及其强化对策——基于执行人员视角的分析   总被引：1，自引：0，他引：1  

汤法远 《毕节学院学报》2006,24(6):44-47

政府公共政策执行力的弱化是一个普遍而严重的问题。导致政府公共政策执行力弱化的根本原因是执行人员观念系统中“经济人”的价值观念过于浓厚和“道德人”的价值观念过于淡薄。具体表现为执行人员缺乏良好的执行心态、缺乏必要的执行素质和能力、执行人员对个人利益和小团体利益的追求以及执行人员队伍思想不统一、行动不协调。强化政府的公共政策执行力,可以从完善执行制度、严明执行纪律和加强以“执行力”和“道德价值”为主要价值取向的执行文化的建设着手。  相似文献   

广西红色旅游发展的SWOT分析与对策     

韦倩虹  黄建清 《内江师范学院学报》2007,22(4):92-95

广西是我国革命老区之一,红色旅游资源非常丰富.全区各地分布着许多红色旅游景点,是人们缅怀先辈丰功伟绩,陶冶情操、净化灵魂的重要场所.文章运用SW OT分析方法,对广西红色旅游发展的优势和劣势、机会和威胁进行了分析,并提出了相应的发展对策.  相似文献   

劳动力市场分割、强弱社会关系与大学毕业生求职     

钟云华 《复旦教育论坛》2012,10(2):34-37,54

论文将劳动力市场划分为体制内劳动力市场与体制外劳动力市场,将大学毕业生的求职过程划分为信息收集与求职进行两个阶段,在一个二元、动态的分析框架内,就强弱社会关系对大学生就业机会获得及起薪水平的影响进行了实证研究。研究发现,强弱社会关系对大学生求职的影响与空间相关:在体制外劳动力市场,弱关系更有助于获得就业信息,弱关系比强关系更"强";但在体制内劳动力市场,强关系比弱关系更"强"。强弱关系对大学生求职的影响也与时间相关:在求职进行阶段,强关系更有助于就业机会获得,强关系比弱关系更"强"。但不管是强关系,还是弱关系,对大学生起薪水平均没有"强"影响,强弱关系对大学生起薪水平的影响与空间及时间都无关。  相似文献   

粘土力学强度分层中的模糊数学模型     

程俊贤  吴海民  杨峰 《宁波大学学报(教育科学版)》1988,(2)

本文依据宁波北仑港海上大量的粘性土工程地质勘察资料和土工试验数据,以传统地质分层为背景,力学强度分层为目标,建立了一套模糊数学评判模型,并用计算机进行数据处理,定量地划分了粘性土的力学强度。  相似文献   

Enhancement of durability of glass fiber-reinforced cement with PVA     

钱晓倩  詹树林 《浙江大学学报(A卷英文版)》2002,3(2):181-187

The main thrust of this research was to determine the effectiveness of polyvinyl alcohol (PVA) powder in enhancing the durability of short GFRC materials. Accelerated aging of the materials was achieved through low-pressure steam curing in a moist chamber. The strength and ductility of GFRC were measured by the direct tension test, which showed that incorporation of PVA powder into GFRC could improve its mechanical behaviour and turn it from brittle to ductile. To investigate the mechanism of the tensile strength enhancement, the fiber-matrix interface was examined by polarizing optical microscopy and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX). It was found that PVA powder tended to migrate to the fiber-matrix interfacial zone and thus prevented the accumulation of calcium hydroxide in this area. PVA film around the fiber resulted in a more ductile interfacial microstructure and better bonding between fiber and matrix, which should be responsible for enhancing the tensile property and preventing the aging of GFRC. Furthermore, PVA powder reduced the microhardness and brittleness at the interface.  相似文献   

奥氏体混晶对钢的力学性能的影响   总被引：3，自引：0，他引：3  

刘天佑 《辽宁科技学院学报》2003,5(3):1-5

文章采用不同的热处理规范(改变加热温度和加热速度)，使钢具有不同的晶粒度(细晶、混晶和粗晶)，进行了拉伸试验和系列冲击试验，探讨了混晶对钢的力学性能的影响。  相似文献   

Ultimate strength of single shear bolted connections with cold-formed ferritic stainless steel     

Jin-seong LIM  Tae-soo KIM  Seung-hun KIM 《浙江大学学报(A卷英文版)》2013,14(2):120-136

This paper is focused on the structural behavior of the single shear bolted connections with thin-walled ferritic stainless steel.The purpose of this study is to investigate the ultimate behaviors,such as ultimate strength and fracture mode of the single shear bolted connections of thin-walled ferritic stainless steel(low cost steel) rather than austenitic stainless steel(high cost steel).Bolt arrangement and end distance parallel to the direction of applied load are considered as main variables of the test specimens for bolted connections.Specimens have a constant dimension of edge distance perpendicular to the loading direction,bolt diameter,pitch,and gauge.A monotonic tensile test for specimens has been carried out and some bolted connections with long end distance showed curling(out of plane deformation) occurrence which led to strength reduction.The ultimate behaviors such as fracture mode,ultimate strength are compared with those predicted by current design codes.Further,conditions of curling occurrence and the strength reduction due to curling are investigated and modified strength equations are suggested considering the curling effect.  相似文献   

近十年中国网球竞技实力提升的实证分析     

刘巍  付甲 《广州体育学院学报》2013,(6):73-76

运用文献资料法、案例分析法等,分析中国网球近十年来在国际大赛中所取得的成绩和名次的上升 。国家网球竞技实力的提升具体表现在几方面：全面参与世界大赛,网球实力初具国际竞争力;积极举办 国际顶级网球赛事,赛事国际影响力日益增强;加强对外合作交流,网球国际地位显著提升。中国网球竞 技实力提升的经验在于：科学把握项目规律和改革方向;坚持训练和管理的不断创新;坚持训练、科研、 教育三结合;坚持统筹兼顾和谐发展;坚持理论与实践的有效转化。  相似文献