混合结构中PBL剪力键群的力学特性研究
发布时间：2018-09-01 09:46
【摘要】：论文首先总结了当前PBL剪力键的研究成果,并在此基础上,设计了3批次28组较大规模的PBL剪力键试验,深入研究混合结构中PBL剪力键的静力性能及变形特征,揭示PBL剪力键的承载机理,厘清剪力键群与单个剪力键之间的内在关系,精确评估混合结构PBL剪力键群的极限承载能力,探索PBL剪力键群的荷载传递规律,提出适合于工程计算的PBL剪力键群荷载传递模型。为此,主要完成了以下六个方面的研究工作：(1)为获得剪力键内钢筋混凝土榫及垂直于开孔板面的约束等微观力学特征,引入分布式传感光纤测试系统,有效地捕捉了PBL剪力键核心构件的应变分布特征；基于弹性地基梁理论和改进的共轭梁理论,分析了穿孔钢筋的力学行为和变形特性,提出了PBL剪力键屈服滑移的理论计算公式；基于对外围混凝土中横向钢筋的分布式应变测量,并结合理论分析,给出了PBL剪力键开孔板界而间竖向滑移与横向膨胀变形的关系曲线,为剪力键承载机理的研究奠定了试验基础。对承载机理试件的试验研究表明：在剪力键屈服滑移以前穿孔钢筋的销栓作用对剪力键的承载力贡献较小,而在加载后期,由于穿孔钢筋剪切曲折引起的“索效应”使得销栓作用渐趋明显。(2)根据混凝土结合面的剪力传递理论,并结合有限元分析,阐明了基于剪力-摩擦理论的PBL剪力键的剪力承载机理,即：混凝土榫在外荷载作用下产生断裂,断裂面相对滑移时其骨料的相互嵌锁导致界面间产生横向膨胀变形,使得垂直于开孔板面约束钢筋的反向夹持作用得到逐步发挥,进而在开孔板开孔附近的椭圆形区域产生了较大的剪切—摩擦效应,连同开孔板界面间的粘聚力及穿孔钢筋的插销作用,构成了混合结构PBL剪力键承载力的三大组成部分。基于对混合结构PBL剪力键承载机理的分析,给出了PBL剪力键单键的极限承载力计算公式,与试验结果比较表明公式具有较高的精度。(3)混合结构PBL剪力键与叠合梁PBL剪力键力学行为的主要区别来源于横向约束的显著不同,为此基于PBL剪力键承载机理的剪力-摩擦理论的相关限制条件,研究确定PBL剪力键横向约束的上限和下限指标；基于混凝土局部分析的拉压杆模型和混凝土的局部承压理论,提出了PBL剪力键合理构造及具体指标的计算公式,分析研究了多排剪力键避免劈裂破坏的理论最小间距需求,为工程设计和应用提供理论支撑。(4)基于非线性有限元数值模拟方法,引入金属材料的延性损伤及剪切损伤本构模型,深入研究了多排PBL剪力键群中穿孔钢筋的塑形变形、损伤发展及失效特性,给出了由穿孔钢筋渐进损伤导致的“索效应”折减系数和剪力-摩擦效应损伤折减系数的计算方法,提出PBL剪力键群极限承载能力的计算公式；基于大量的PBL剪力键的试验测试数据,提出PBL剪力键弹性刚度的计算公式；结合剪力键的剪力-摩擦承载机理,综合确定了混合结构PBL剪力键群的正常使用极限状态指标；基于快速模拟退火算法,提出了准确的多参数的PBL剪力键荷载-滑移本构方程。(5)为明晰多排多列剪力键之间的相互影响,通过对穿孔钢筋的夹持力作用的弹簧比拟,基于弹性地基板理论,提出了剪力键的影响作用半径的计算公式。基于分布式光纤的剪力键开孔板应变分布研究表明：开孔板面沿加载方向的空间应变分布可退化为二维平面化的应变分布；沿加载方向开孔板的归一化应变可采用Lorentz曲线来表征。基于PBL剪力键归一化应变的Lorentz分布曲线的数学特征,引入连续化的分析方法,推导了剪力键群竖向受力的基本微分方程,提出了PBL剪力键群荷载传递模型及其迭代算法。与试验结果对比表明,该算法计算方便、理论意义明确,具有足够的工程精度。(6)为数值模拟剪力键群的承载能力及荷载传递行为,引入了ALE自适应网格技术和子循环集成高级算法,进行了混凝土材料特性扩展的二次开发,编写了用户自定义场变量子程序(USDFLD),实现了对混凝土剪胀角功能梯度模型的有效模拟,准确模拟了混凝土榫的剪胀、穿孔钢筋的损伤及剪力键的屈服强化特征,为PBL剪力键的有限元仿真分析提供了详尽的参数取值及经验借鉴。
[Abstract]:Firstly, the paper summarizes the current research results of PBL shear bonds, and on this basis, designs three batches of 28 groups of large-scale PBL shear bond tests, in-depth study of the static performance and deformation characteristics of PBL shear bonds in hybrid structures, reveals the bearing mechanism of PBL shear bonds, clarifies the internal relationship between shear bond groups and a single shear bond, accurate. This paper evaluates the ultimate bearing capacity of PBL shear bond groups in hybrid structures, explores the load transfer law of PBL shear bond groups, and proposes a load transfer model for PBL shear bond groups suitable for engineering calculation. Based on the elastic foundation beam theory and the improved conjugate beam theory, the mechanical behavior and deformation characteristics of perforated steel bar are analyzed, and the theoretical calculation formula of PBL shear bond yield slip is proposed. Distributed strain measurement of transverse reinforcing bars in peripheral concrete and theoretical analysis are carried out. The relationship between vertical slip and transverse expansion deformation of PBL shear bond perforated slab boundaries is given, which lays the experimental foundation for the study of shear bond loading mechanism. The pin-bolt effect of perforated steel bars contributes little to the bearing capacity of shear bonds, but the "cable effect" caused by the shear tortuosity of perforated steel bars makes the pin-bolt effect become more and more obvious in the later stage of loading. (2) According to the shear transfer theory of concrete joint surface and finite element analysis, the shear force of PBL shear bonds based on shear-friction theory is clarified. Load-bearing mechanism, that is, concrete tenon fracture under external load, the interlocking of the aggregate when the fracture surface relative slip, resulting in transverse expansion deformation between the interface, so that vertical to the orifice plate restraint bar reverse clamping effect is gradually exerted, and then in the vicinity of the orifice plate elliptical region produced a larger. The shear-friction effect, together with the cohesion between perforated plates and the pinning effect of perforated steel bars, constitutes three major components of the bearing capacity of PBL shear bonds in hybrid structures. (3) The main difference of mechanical behavior between PBL shear bonds of hybrid structures and composite beams is due to the significant difference of transverse constraints. Based on the shear-friction theory of PBL shear bonds, the upper and lower bounds of transverse constraints of PBL shear bonds are determined. Based on the partial analysis of the tension-compression bar model and the local compression theory of concrete, the calculation formulas of the reasonable construction and specific indexes of PBL shear bonds are proposed. The theoretical minimum spacing requirement of multi-row shear bonds to avoid splitting failure is analyzed and studied, which provides theoretical support for engineering design and application. (4) Based on the nonlinear finite element numerical simulation method, gold is introduced. The plastic deformation, damage development and failure characteristics of perforated steel bars in multi-row PBL shear bond groups are studied. The calculation methods of cable effect reduction coefficient and shear-friction damage reduction coefficient caused by progressive damage of perforated steel bars are given. The shear bond group poles of PBL are proposed. Based on a large number of test data of PBL shear keys, a formula for calculating the elastic stiffness of PBL shear keys is proposed. Combined with the shear-friction bearing mechanism of shear keys, the limit state index of PBL shear keys in hybrid structures is determined comprehensively. Based on the fast simulated annealing algorithm, an accurate limit state index is proposed. The load-slip constitutive equation of multi-parameter PBL shear bonds. (5) To clarify the interaction between multi-row and multi-row shear bonds, a formula for calculating the influence radius of shear bonds is proposed based on the elastic foundation plate theory through the spring analogy of the clamping force of perforated steel bars. The results show that the spatial strain distribution along the loading direction can be reduced to two-dimensional planar strain distribution, and the normalized strain along the loading direction can be represented by Lorentz curve. The load transfer model and its iterative algorithm of PBL shear bond group are presented. The results show that the algorithm is convenient to calculate, has clear theoretical significance and has sufficient engineering accuracy. (6) To simulate the bearing capacity and load transfer behavior of shear bond group numerically, the ALE adaptive grid technique is introduced. A user-defined field variable subroutine (USDFLD) was compiled to simulate the dilatancy angle function gradient model of concrete effectively. The dilatancy of tenon, the damage of perforated steel bar and the yielding and strengthening characteristics of shear keys were simulated accurately. The finite element simulation analysis of shear connectors provides detailed parameter values and experience.
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U441;U448.38
，
本文编号：2216819
[Abstract]:Firstly, the paper summarizes the current research results of PBL shear bonds, and on this basis, designs three batches of 28 groups of large-scale PBL shear bond tests, in-depth study of the static performance and deformation characteristics of PBL shear bonds in hybrid structures, reveals the bearing mechanism of PBL shear bonds, clarifies the internal relationship between shear bond groups and a single shear bond, accurate. This paper evaluates the ultimate bearing capacity of PBL shear bond groups in hybrid structures, explores the load transfer law of PBL shear bond groups, and proposes a load transfer model for PBL shear bond groups suitable for engineering calculation. Based on the elastic foundation beam theory and the improved conjugate beam theory, the mechanical behavior and deformation characteristics of perforated steel bar are analyzed, and the theoretical calculation formula of PBL shear bond yield slip is proposed. Distributed strain measurement of transverse reinforcing bars in peripheral concrete and theoretical analysis are carried out. The relationship between vertical slip and transverse expansion deformation of PBL shear bond perforated slab boundaries is given, which lays the experimental foundation for the study of shear bond loading mechanism. The pin-bolt effect of perforated steel bars contributes little to the bearing capacity of shear bonds, but the "cable effect" caused by the shear tortuosity of perforated steel bars makes the pin-bolt effect become more and more obvious in the later stage of loading. (2) According to the shear transfer theory of concrete joint surface and finite element analysis, the shear force of PBL shear bonds based on shear-friction theory is clarified. Load-bearing mechanism, that is, concrete tenon fracture under external load, the interlocking of the aggregate when the fracture surface relative slip, resulting in transverse expansion deformation between the interface, so that vertical to the orifice plate restraint bar reverse clamping effect is gradually exerted, and then in the vicinity of the orifice plate elliptical region produced a larger. The shear-friction effect, together with the cohesion between perforated plates and the pinning effect of perforated steel bars, constitutes three major components of the bearing capacity of PBL shear bonds in hybrid structures. (3) The main difference of mechanical behavior between PBL shear bonds of hybrid structures and composite beams is due to the significant difference of transverse constraints. Based on the shear-friction theory of PBL shear bonds, the upper and lower bounds of transverse constraints of PBL shear bonds are determined. Based on the partial analysis of the tension-compression bar model and the local compression theory of concrete, the calculation formulas of the reasonable construction and specific indexes of PBL shear bonds are proposed. The theoretical minimum spacing requirement of multi-row shear bonds to avoid splitting failure is analyzed and studied, which provides theoretical support for engineering design and application. (4) Based on the nonlinear finite element numerical simulation method, gold is introduced. The plastic deformation, damage development and failure characteristics of perforated steel bars in multi-row PBL shear bond groups are studied. The calculation methods of cable effect reduction coefficient and shear-friction damage reduction coefficient caused by progressive damage of perforated steel bars are given. The shear bond group poles of PBL are proposed. Based on a large number of test data of PBL shear keys, a formula for calculating the elastic stiffness of PBL shear keys is proposed. Combined with the shear-friction bearing mechanism of shear keys, the limit state index of PBL shear keys in hybrid structures is determined comprehensively. Based on the fast simulated annealing algorithm, an accurate limit state index is proposed. The load-slip constitutive equation of multi-parameter PBL shear bonds. (5) To clarify the interaction between multi-row and multi-row shear bonds, a formula for calculating the influence radius of shear bonds is proposed based on the elastic foundation plate theory through the spring analogy of the clamping force of perforated steel bars. The results show that the spatial strain distribution along the loading direction can be reduced to two-dimensional planar strain distribution, and the normalized strain along the loading direction can be represented by Lorentz curve. The load transfer model and its iterative algorithm of PBL shear bond group are presented. The results show that the algorithm is convenient to calculate, has clear theoretical significance and has sufficient engineering accuracy. (6) To simulate the bearing capacity and load transfer behavior of shear bond group numerically, the ALE adaptive grid technique is introduced. A user-defined field variable subroutine (USDFLD) was compiled to simulate the dilatancy angle function gradient model of concrete effectively. The dilatancy of tenon, the damage of perforated steel bar and the yielding and strengthening characteristics of shear keys were simulated accurately. The finite element simulation analysis of shear connectors provides detailed parameter values and experience.
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U441;U448.38
，
本文编号：2216819
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