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《内置横向加劲钢筋方钢管混凝土柱基本力学性能研究》.PDF 李楠

《内置横向加劲钢筋方钢管混凝土柱基本力学性能研究》.PDF 李楠

学科:岩土工程. 矿山结构理论与应用,出版时间:2017,导师:王来指导,学位授予单位:山东科技大学,论文作者:李楠著,

中文

基于方钢管混凝土约束和粘结滑移原理,为更好的发挥方钢管混凝土柱中核心混凝土抗压强度和塑性变形能力,提出了一种新型方钢管混凝土柱截面形式,即内置横向加劲钢筋方钢管混凝土柱。管壁内置横向加劲钢筋可提高核心混凝土有效约束性能,延缓管壁钢板的局部屈曲,同时能提高钢管和混凝土界面粘结和抗滑移能力,基于此,开展了内置横向加劲钢筋方钢管混凝土柱基本力学性能研究。 (1)内置横向加劲钢筋方钢管混凝土柱轴压力学性能研究。通过轴压试验,分析了内置横向加劲钢筋方钢管混凝土柱的轴压力学性能和破坏模式;轴向荷载与位移变化规律以及不同截面处纵、横向应变的变化规律;分析了柱子延性及含钢率变化对轴压承载力的影响。试验结果表明:内置横向加劲钢筋方钢管混凝土柱承载力和延性比普通方钢管混凝土柱有不同程度的提高,轴压承载力最大提高幅度为15%,延性系数提高至1.74~1.96;由于横向加劲钢筋的作用,内置横向加劲钢筋方钢管混凝土柱加载阶段的横向应变小于方钢管混凝土的横向应变,内置横向加劲钢筋使方钢管对核心混凝土的约束效应提高;减小横向钢筋间距较增加直径更能有效提高其极限承载力和延性。在轴压试验基础上,完成内置横向加劲钢筋方钢管混凝土柱轴压承载力理论研究。基于Mander的箍筋约束混凝土理论,提出了内置横向加劲钢筋方钢管混凝土柱中约束混凝土的本构曲线;基于叠加理论,将内置横向加劲钢筋方钢管混凝土柱中核心混凝土分为内置横向加劲钢筋方钢管作用的有效约束区和非有效约束区,对内置横向钢筋方钢管作用的有效约束区核心混凝土引入考虑侧向约束系数影响的强度,通过极限平衡理论以及钢材的Von Mises屈服条件,推导出内置横向钢筋方钢管混凝土柱承载力理论计算公式;此外基于钢管混凝土统一理论提出了内置横向加劲钢筋方钢管混凝土柱承载力简化计算公式。 (2)内置横向加劲钢筋方钢管混凝土柱粘结滑移力学性能研究。通过方钢管混凝土柱推出试验,分析了方钢管混凝土柱及内置横向加劲钢筋方钢管混凝土柱的粘结滑移性能;分析了荷载-滑移曲线以及不同加载阶段不同部位粘结应力的变化特征。粘结强度影响因素方面的分析表明:随着试件长径比、截面宽厚比、有效粘结长度的增加有减小的趋势,随着横向钢筋布置间距的减小而增大。在此基础上,推导了内置横向加劲方钢管混凝土粘结强度的理论计算公式。基于推出试验结果,提出了内置横向加劲钢筋方钢管混凝土柱的粘结滑移本构关系。 (3)内置横向加劲钢筋方钢管混凝土柱轴向荷载力学性能数值模拟。采用三维非线性有限元分析方法,考虑横向加劲设置对管内核心混凝土约束和粘结作用的提升,完成了柱轴压承载力的模拟计算并分析柱截面的应力变化特征,对影响柱轴压承载力的各因素进行对比分析,研究结果表明:钢管强度、钢材强度、钢筋布置间距、含钢量等因素对柱轴压承载力的提高产生明显影响。 关键词:方钢管混凝土柱,内置横向加劲钢筋,轴压,粘结滑移,力学性能

英文

Based on the principle of constraint and bond-slip, in order to fully improve the core concrete compressive strength and the plastic deformation capacity of the steel square tubular column, a new type of concrete filled steel tubular column with internal transverse stiffened bars is put forward. The internal transverse stiffened bars are configured to effectively restrict the deformation of the core concrete of the concrete steel tubular column. The internal transverse stiffened bars can improve not only the bearing capacity and plastic deformation of the concrete filled steel tubular column but also mechanical properties of bond-slip. According this, the basic mechanical properties of the square concrete filled steel tubular column with internal transverse stiffened bars is studied. (1)The research on axial compression properties of concrete filled square steel tubular column with internal transverse stiffened bars. Mechanical properties and damage mode of the square concrete filled steel tubular column with transverse stiffened bars are analyzed. The change rule of displacement and strain of all section and the effects of use of steel and index of ductility are analyzed. The experimental results show that the bearing capability of concrete filled square steel tubular column with transverse stiffened bars is 15% higher than that of concrete filled steel tubular column and the ductility index is 1.74~1.96. Because of the constraint of transverse stiffened bars on core concrete, transverse strain of the concrete filled square steel tubular column with transverse stiffened bars is less than that of the square concrete filled steel tubular column. Transverse strain of the concrete filled square steel tubular column with transverse stiffened bars changes is more uniform from the top to the bottom. Relative to the increase of the diameter of the transverse stiffened bars, reduce of the bar space can be more effective to increase the ultimate bearing capacity and ductility for the concrete filled square steel tubular column with transverse stiffened bars. On the basis of the experiment, the theoretical research on the bearing capacity of concrete filled square steel tubular column with internal transverse stiffened bars is carried out. Based on Mander’s theory of confined concrete, a constitutive relation of confined concrete is proposed. Based on the superimposed theory, the core concrete of concrete filled square steel tubular column with internal transverse stiffened bars is divided into the effective confining region and the non-effective confining region with internal transverse stiffened bars. For the first time, the effect of the lateral confinement coefficient is taken into account in the effective confining region of the core concrete. The theoretical formula of the bearing capacity of the concrete filled square steel tubular column with internal transverse stiffened bars is deduced by the limit equilibrium theory and the Von-Mises yield criterion of the steel. In addition, based on the unified theory of concrete filled steel tube, a simplified formula for calculating the bearing capacity of concrete filled square steel tubular column with internal transverse stiffened bars is proposed. (2) The research on bond slip properties of concrete filled square steel tubular column with internal transverse stiffened bars.Through the push-out test of concrete filled square steel tubular column with internal transverse stiffened bars, the mechanical properties of bond and slip is analyzed. The curve of the bond-slip of all load phase and the effects of bond strength are analyzed. The results show that with the increase of ratio of length-diameter, ratio of width-thickness, effective bond length and decrease of bar spacing, the bond strength increased. Based on the experiment results, the theoritic fomular and constitutional relation of bond and slip is put forward. (3) Numerical simulation on mechanical properties of concrete filled square steel tubular column with internal transverse stiffened bars. Finite element analysis software ABAQUS is used to simulate the load capacity and the change characteristics of stress on all section according to the promotion of confinement and bond. The results show that the strength of the steel tube, the strength of the steel bar, the diameter of the steel bar, the spacing of the steel bars and the amount of the steel have significant influence on the bearing capacity of the column. KEY WORDS: concrete filled square steel tubular column; internal transverse stiffened bars; axial compression; bond-slip;mechanical properties

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