劲化矩形截面钢管混凝土短柱力学性能的研究

发布时间：2018-05-27 06:39

本文选题：矩形钢管混凝土柱 + 劲化带　；参考：《华南理工大学》2014年博士论文

【摘要】：矩形钢管混凝土的钢管对核心混凝土约束主要集中在角部，在四个侧边中部约束作用较小，所以矩形钢管对核心混凝土的整体约束效应远不及圆形钢管混凝土，导致其承载力远低于圆形钢管混凝土柱。与方形钢管混凝土相比，矩形钢管截面长宽边长不同，长边对核心混凝土的约束作用弱，较短边更易发生局部屈曲。但由于约束作用的存在，只要设置得当，其承载力比按钢管和混凝土两种材料单轴强度简单叠加计算要高。为了改善矩形截面钢管混凝土柱构件的力学性能，在矩形截面钢管混凝土柱中沿纵向每隔一定间距的横截面上设置横向水平约束拉杆（钢筋），一方面能限制该部位核心混凝土的横向变形，另一方面能为钢管提供侧向支撑作用而使钢板的局部屈曲强度提高。约束拉杆的设置能极大改进矩形钢管混凝土柱的力学性能，但约束拉杆之间区域仍出现弹塑性局部屈曲现象，，对内填混凝土的约束作用受到削弱。劲化矩形钢管混凝土柱通过加设劲化带形成劲化带与约束拉杆的和谐搭配，在增加极少用钢量又不增加施工难度，影响施工进度的情况下，最大限度的减缓约束拉杆之间的弹塑性屈曲，提高侧面约束能力，改善矩形钢管混凝土柱的力学性能。本文对矩形钢管混凝土柱的劲化设计，基于已有研究成果，在满足高层建筑结构安全的前提下，能较大限度地用较薄的钢板厚度，实现较高的强度、刚度以及延性。基于上述分析，本文对劲化矩形钢管混凝土柱的轴压、偏压、滞回性能进行了系列研究。 (1)以约束拉杆水平间距、纵向间距、劲化带截面、劲化带设置方式为研究参数，共进行10个方形钢管混凝土柱试件的轴压承载力试验。分析各参数对试件的破坏形态、受力特点、应变特点、承载力及延性等力学性能的影响，为后述的研究提供基本试验资料。 (2)以钢板厚度、约束拉杆直径、约束拉杆强度、劲化带截面、劲化带设置方式为研究参数，采用拟静力试验方法对构件施加低周水平力反复荷载作用，共进行16个方形钢管混凝土柱试件的低周水平力反复荷载试验。分析在不同参数下，各个构件的滞回曲线、骨架曲线，从而计算出各个构件的承载力及其退化，刚度及其退化、位移延性系数、耗能能力。由试验结果采用三折线计算模型回归分析、确定了劲化方钢管混凝土柱的骨架曲线模型参数，为这种新型构件在超高层工程中设计分析提供参考。 (3)对劲化矩形钢管混凝土柱的约束机理进行了分析。矩形钢管截面长边、短边对混凝土约束作用大小不同，及约束拉杆沿长边、短边布置数量不同。基于核心混凝土真三轴受压的特点，提出了劲化矩形钢板内核心混凝土的等效单轴本构关系。采用该本构关系对劲化矩形钢管混凝土轴压构件的荷载-变形关系曲线进行全过程数值分析，验证了计算曲线与试验曲线的吻合性。 (4)为与试验监测结果相互印证，根据本文提出的劲化矩形钢板内填混凝土的本构关系，对所有试件进行了三维双重非线性有限元分析，深入揭示劲化带及约束拉杆对核心混凝土及钢管应力分布的影响，对各个试件进行了对比。有限元分析结果与试验结果基本相符。通过建立模型，扩大参数，利用有限元分析各种劲化方式、劲化参数下构件的侧向约束效果。 (5)该类构件在各种劲化方式下的轴压承载力有很大差别，不能用一个统一的公式表述。采用本文提出的劲化矩形钢板混凝土本构关系，推导得出该类构件在各种劲化方式下的轴压承载力计算公式。采用本文提出的劲化矩形钢管混凝土柱的轴压承载力计算公式对轴压试件的承载力进行计算，计算结果与试验结果、有限元分析结果吻合良好；基于已有研究成果，本文方法能合理地评估劲化矩形钢管混凝土短柱的轴压承载力。 (6)采用劲化矩形钢管核心混凝土的本构关系，利用截面网格单元法对偏压劲化矩形钢管混凝土柱试件进行数值分析，并用有限元法进行了验证，吻合良好，可以用来合理评估矩形钢管混凝土短柱的偏压承载力。
[Abstract]:The core concrete constraints of concrete-filled rectangular steel tube are mainly concentrated in the corner, and the confinement effect is less in the middle of the four sides, so the overall constraint effect of the rectangular steel pipe to the core concrete is far less than the circular concrete filled steel tube, which leads to its bearing force far below the circular steel pipe concrete column. Compared with the square steel tube concrete, the rectangular steel tube is compared. The length and width of the cross section is different, the long edge has a weak constraint on the core concrete, and the local buckling is easier to occur on the shorter side. However, because of the existence of the constraint, the bearing capacity is higher than the simple superposition of the uniaxial strength of the two kinds of steel tubes and concrete as long as the setting is proper.
In order to improve the mechanical properties of the rectangular section of the concrete filled steel tube column, the transverse horizontal restraint rod (steel bar) is set along the longitudinal cross section of the rectangular cross section concrete filled steel tube column. On the one hand, the transverse deformation of the core concrete can be restricted, and the other side can provide the lateral support for the steel pipe to make the steel plate. The local buckling strength of the confined bar can be improved greatly. However, the mechanical properties of the rectangular steel tube concrete column can be greatly improved, but the elastoplastic local buckling still appears in the zone between the restrained bars, and the restraining effect on the concrete is weakened.
The stiffening rectangular concrete-filled steel tube column is formed by adding the stiffening belt to form the harmonious collocation of the stiffening belt and the restraint rod. In the case of increasing the minimum steel quantity without increasing the construction difficulty and affecting the construction progress, the elastoplastic buckling of the restraint rod is restrained to the maximum limit, the lateral restraint ability is raised and the mechanics of the rectangular steel tube concrete column is improved. Performance.
In this paper, the stiffening design of rectangular concrete-filled steel tube column is based on the existing research results. On the premise of meeting the safety of the high-rise building structure, the thin steel plate thickness can be used to achieve higher strength, stiffness and ductility.
Based on the above analysis, the axial compression, bias and hysteretic behavior of rectangular concrete-filled steel tubular columns are studied in series.
(1) the axial compression bearing capacity test of 10 square concrete-filled steel tubular column specimens is carried out by restraining the horizontal spacing, longitudinal spacing, stiffening zone section and stiffening belt setting method as the research parameters. The effects of various parameters on the failure form, stress characteristics, strain characteristics, load bearing force and ductility of the specimens are analyzed to provide the following research. Basic test data.
(2) the low cycle horizontal force test of 16 square concrete-filled steel tube columns is carried out with the thickness of steel plate, constraint rod diameter, restraint tension bar strength, stiffening band cross section and stiffening belt setting method as the research parameters, and a total of 16 square steel tube concrete column specimens are tested under different parameters. The load-bearing capacity and its degradation, stiffness and its degradation, displacement ductility coefficient and energy dissipation capacity of each component are calculated by the hysteretic curve and skeleton curve of the component. The model parameters of the skeleton curve of the stiffened square steel tube concrete column are determined by the regression analysis of the three fold line calculation model, and the new component is used in the super high rise project. The design analysis provides reference.
(3) the constraint mechanism of the stiffened rectangular concrete-filled steel tube column is analyzed. The length of the rectangular steel tube is different from the long side and the short side to the concrete, and the number of the short side arrangement is different. Based on the characteristic of the true three axis compression of the core concrete, the equivalent uniaxial constitutive model of the core concrete in the stiffened rectangular steel plate is put forward. The relationship between the load deformation relation curve of the rigid rectangular concrete filled steel tube axial compression member is analyzed by the constitutive relation, and the agreement between the calculated curve and the test curve is verified.
(4) in order to verify the results of the test monitoring, according to the constitutive relation of the stiffened rectangular steel plate filled with concrete, the three-dimensional double nonlinear finite element analysis is carried out for all the specimens, and the effects of the stiffening belt and the restrained pull rod on the stress distribution of the core concrete and the steel pipe are deeply revealed. The analysis results are basically consistent with the experimental results. Through the establishment of the model, the parameters are expanded, the finite element method is used to analyze various stiffening methods and the lateral restraining effect of the component under the stiffening parameters.
(5) the axial compression bearing capacity of this kind of component is very different in various stiffening ways and can not be expressed by a unified formula. By using the constitutive relation of stiffened rectangular steel plate concrete proposed in this paper, the axial compression bearing capacity of this kind of member under various stiffening methods is derived. The stiffened rectangular concrete-filled steel tube is adopted in this paper. The calculation formula of the axial compression bearing capacity of the column is used to calculate the bearing capacity of the axial compression specimen. The calculation results are in good agreement with the experimental results and the finite element analysis results. Based on the existing research results, this method can reasonably evaluate the axial compressive bearing capacity of the stiffened rectangular concrete-filled steel tube short column.
(6) using the constitutive relation of the stiffened rectangular steel tube core concrete, the section grid element method is used to carry out numerical analysis of the eccentric compression stiffened rectangular concrete-filled steel tube column, and the finite element method is used to verify it. It is in good agreement and can be used to reasonably evaluate the bearing capacity of the rectangular concrete filled steel tube short column.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU398.9

【参考文献】