钢管RPC短柱静力及抗冲击性能研究

发布时间：2018-02-11 21:41

本文关键词： 统一强度理论钢管RPC 轴压承载力界面粘结性能冲击荷载 SHPB数值模拟　出处：《长安大学》2014年博士论文　论文类型：学位论文

【摘要】：活性粉末混凝土(简称RPC)作为绿色高性能混凝土具有超高强度、高韧性、耐久性好、体积稳定性优良的特点，是混凝土未来的发展方向。将其应用于组合结构形成钢管活性粉末混凝土结构构件，对其研究具有重要的理论意义和工程应用价值。本文研究了不同截面形式钢管RPC的轴压性能、粘结滑移与界面粘结损伤性能、尺寸效应模型和钢管RPC的抗冲击性能。主要的研究工作和创新成果如下： (1)以统一强度理论和厚壁圆筒理论为基础，推导了圆形、方形和圆端形截面钢管RPC轴压短柱的承载力计算公式。运用势能驻值原理，考虑钢管和RPC之间的套箍效应，推导出钢管RPC柱在轴向压力作用下组合弹性模量的计算式，并进一步分析钢管RPC柱的组合轴压刚度。采用粘结强度和割线模量定义了界面粘结损伤变量，建立了一种基于损伤理论的钢管与RPC的界面粘结损伤模型，揭示了钢管RPC界面粘结的损伤机理。 (2)基于统一屈服准则和应变梯度塑性理论，推导考虑尺寸效应的厚壁圆筒塑性极限解，得到考虑尺寸效应的外钢管的纵向抗压强度，研究了钢管RPC的尺寸效应规律及不同变形条件下尺寸效应的作用机理。采用Weibull统计尺寸效应模型对核心RPC的抗压强度进行修正，对外钢管采用考虑尺寸效应的厚壁圆筒理论，从而对不同截面形式的钢管RPC轴压短柱提出了考虑界面粘结性能和尺寸效应的轴压承载力计算方法，，并探讨了强度理论参数、套箍指标和活性粉末混凝土强度对承载力的影响特性。 (3)采用三段线近似模拟钢管RPC的粘结滑移本构模型，以便于进行ANSYS数值模拟时弹簧单元的施加。对于钢管RPC粘结滑移数值模拟采用非线性弹簧单元Combination39，分析了该单元的特点以及F D曲线选取的计算方法。非线性弹簧单元分别模拟了钢管与活性粉末混凝土之间法向、纵向切向、环向切向三个方向的作用。利用ANSYS后处理器得到的不同截面形式钢管RPC短柱的轴压承载力和荷载-变形关系曲线，与文献中试验曲线吻合较好，探讨了RPC轴压强度、套箍系数和轴压刚度比对钢管RPC轴压短柱极限承载力的影响。 (4)采用LS-DYNA软件对RPC短柱和钢管RPC短柱进行分离式霍普金森压杆(简称SHPB)有限元数值模拟。数值分析得到的应力波的波形图、构件的轴向应力时程和轴向应变时程、重构的应力应变曲线均与试验结果基本一致，证明了有限元模型的合理性。基于CEB公式和Malver公式推导钢管RPC试件的动态增长因子计算表达式，给出了三波法和两波法计算试件应变、应力和应变率的基本公式。研究了冲击荷载作用下RPC应变率强化的特性、试件破坏过程以及动态增长因子的响应规律，探讨了活性粉末混凝土强度、钢管壁厚度、套箍系数等因素对钢管RPC构件的抗冲击性能的影响特性。
[Abstract]:As green high performance concrete, reactive powder concrete (RPC) has the characteristics of super high strength, high toughness, good durability and good volume stability. It is the development direction of concrete in the future. In this paper, the axial compression behavior, bond-slip and interfacial bond damage of steel tube RPC with different cross-section forms are studied. Size effect model and impact resistance of steel tube RPC. The main research and innovative results are as follows:. 1) based on the unified strength theory and the thick wall cylinder theory, the formulas for calculating the bearing capacity of RPC short columns with circular, square and circular end sections are derived. The hoop effect between the steel tube and RPC is considered by using the principle of standing potential energy. The formula of composite elastic modulus of steel tube RPC column under axial pressure is derived, and the combined axial compression stiffness of steel tube RPC column is further analyzed. The interface bond damage variable is defined by bond strength and Secant modulus. A damage model of interface bond between steel tube and RPC is established based on damage theory, and the mechanism of interface bond damage of steel tube RPC is revealed. Based on the unified yield criterion and strain gradient plasticity theory, the plastic limit solution of thick-walled cylinder considering size effect is derived, and the longitudinal compressive strength of outer steel pipe considering size effect is obtained. The size effect law of steel tube RPC and the action mechanism of dimension effect under different deformation conditions are studied. The compressive strength of core RPC is modified by Weibull statistical size effect model, and the thick-walled cylinder theory considering size effect is adopted in external steel pipe. Thus, the calculation method of axial compression capacity of steel tube RPC short columns with different cross-section forms considering the interfacial bond property and size effect is put forward, and the theoretical strength parameters are discussed. The influence of hoop index and reactive powder concrete strength on bearing capacity. The bond-slip constitutive model of steel pipe RPC is simulated by three-segment line approximation. In order to facilitate the application of spring element in ANSYS numerical simulation, the nonlinear spring element combination 39 is used in the numerical simulation of RPC bond-slip of steel pipe. The characteristics of the element and the calculation method of selecting F-D curve are analyzed. The normal direction between the steel tube and the reactive powder concrete was simulated by the element. The axial bearing capacity and load-deformation relation curves of RPC short columns with different cross-section obtained by ANSYS post-processor are in good agreement with the experimental curves in literature. The axial compression strength of RPC is discussed. The influence of hoop coefficient and axial compression stiffness ratio on ultimate bearing capacity of steel tube RPC short columns under axial compression. (4) finite element numerical simulation of split Hopkinson compression bar (SHPB) for RPC short column and RPC tube short column is carried out by using LS-DYNA software. The waveforms of stress wave, axial stress time history and axial strain time history are obtained by numerical analysis. The reconstructed stress-strain curves are basically consistent with the experimental results, which proves the rationality of the finite element model. Based on the CEB formula and the Malver formula, the expression of the dynamic growth factor of the steel tube RPC specimen is derived. The basic formulas for calculating strain, stress and strain rate of specimen by three wave method and two wave method are given. The characteristics of strain rate strengthening of RPC under impact load, the failure process of the specimen and the response law of dynamic growth factor are studied. The effects of the strength of reactive powder concrete (RPC), the thickness of steel tube wall and the hoop coefficient on the impact resistance of steel tube RPC members are discussed.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU398.9;TU317

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