【作者】 原海燕；

【导师】 阎贵平； 安明喆；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 活性粉末混凝土(Reactive Powder Concrete,简称为RPC)具有高强度、高韧性、高耐久性等特点,其抗压强度及抗拉韧性远远高于常规混凝土,是土木工程领域中极具应用前景的一种新型材料。由于RPC在工程应用多以配筋结构的形式出现,因此进行配筋RPC的受拉性能研究具有重要的理论与现实意义。本文结合863国家高技术研究发展计划项目(2006AA032536)及国家自然科学基金项目(50508005),对RPC配筋前后受拉力学性能进行了轴拉全过程试验研究,所作的主要工作及结论如下:(1)在总结国内外大量试验研究成果的基础上,应用自行设计的外央式轴拉试验装置,完成了无筋RPC及配筋RPC轴拉全过程试验。试验中采用变截面弧形过渡的哑铃型试件,配合变厚度铜垫片,解决了外夹式试件易在端部产生应力集中的问题,试验方法简单、可靠,具有独创性;(2)进行了无筋RPC及配筋RPC轴拉全过程试验研究,试验表明:在普通万能试验机上不添加任何刚度辅助设施,能够测出钢纤维体积率V_f=1%、V_f=2%时的RPC轴拉应力—应变全曲线,其轴拉破坏形式由无纤维时的脆性破坏转为韧性破坏;配筋RPC试件在轴拉试验中表现出良好的限裂性能,随配筋率参数不同,其破坏形式分为两种:即:nρ＜0.20时的单缝破坏,和nρ≥0.20时的多缝破坏;(3)分析了RPC约束收缩对试验结果的影响,提出了配筋RPC约束收缩修正方法,据此得到了剔除收缩影响后各组试件的配筋RPC受拉应力—应变曲线,通过对比分析得出配筋对RPC受拉应力—应变曲线的影响主要在下降段,配筋率参数nρ是主要影响因素;(4)根据试验分析结果,建立了配筋RPC轴拉本构的三折线式理论模型,及其实用简化模型,为配筋RPC受拉构件全过程非线性分析的本构模型选取提供了理论依据;(5)从RPC微观结构及断裂力学理论出发,分析了无筋RPC及配筋RPC受拉性能的机理,解释了RPC轴拉高韧性,以及配筋RPC良好限裂性能的原因。更多还原

【Abstract】 Reactive Powder Concrete(RPC) is a new generation concrete material,compared with conventional concrete,it possesses excellent properties such as ultra-high strength,high toughness and high durability etc.The excellent characteristics especially for high compressive strength and high tensile toughness make RPC a revolutionary application prospect in civil engineering field.For RPC is often reinforced by steel bars in application,it has great theoretical and practical signigicance to carry out the experimental research of RPC and reinforced RPC on their tensile behavior.Based on the national natural science foundation of China,the uniaxial tensile tests of RPC and reinforced RPC are developed,and the investigated results can be listed as follows:(1) Based on the reference review and experimental results,a self-designed uniaxial tensile test equipment is developed.RPC as well as reinforced RPC uniaxial tensile tests are completed.In order to solve the stress concentration problem,a dumbbell-shaped specimen combined with variable-thickness copper sheet is used in the test and gains satisfied effect.The innovative test method developed by author is suitable for reinforced concrete in direct tension;(2) The test reveals that the complete uniaxal tensile stress-strain curve of RPC (V_f =1%,2%) can be obtained through Universal Testing Machine without any stiffness-strengthen devices.The test also shows that the tensile failure mode of RPC changed from brittleness to ductility before and after steel fiber added.As for reinforced RPC,it is found that all specimens exhibit well restricted-fissure performance when strengthed with steel bar.There are two types failure mode of reinforced RPC in uniaxial tensile test,that is,single-slit failure when np＜0.20 and multiple-slit failure when np≥0.20;(3) In view of the effect of restrained shrinkage on tensile test results,a restrained shrinkage modified model of reinforced RPC is developed.Based on this model, tensile stress-strain curves eliminated shrinkage effection of reinforced RPC are abtained.Comparative analysis shows that after strengthed by steel bar,the descending segment of RPC tensile stress-strain curve is mainly influenced,and reinforcement ratio parameter n,o is the main influential factor;(4) According to analytical results,a theoretial trilinear constitutive model of reinforced RPC tensile stress-strain curve is constructed.For the sake of convenience,a practical simplified tensile stress-strain model of reinforced RPC is also presented. These two theoretical models can provide theoretical basis to the whole process nonlinear analysis of reinforced RPC structures;(5) Based on microstructure of RPC and fracture mechanics theory,the tensile mechanism of RPC and reinforced RPC are studied.The reasons of high toughness of RPC and well restricted-fissure performance of reinforced RPC are interpreted.更多还原