【作者】 肖海兵；

【导师】 赵均海；

【作者基本信息】 长安大学 ， 结构工程， 2010， 硕士

【摘要】 薄壁钢管轻骨料混凝土是随着现代建筑结构材料发展要求而出现的新的组合结构。该结构具有承载力高、塑性和韧性好、施工方便、耐火性能高、抗震性能好和经济效益好等优点,因此该结构在工程实践中具有较广阔的应用前景,尤其在多低层建筑中的应用。而薄壁钢管轻骨料混凝土的研究工作才刚刚起步,有关该方面的研究也较少,尚未形成相关的规范和规程。进行该结构体系轴压力学性能的理论研究,对该结构体系的进一步研究是十分必要的。本文运用统一强度理论对薄壁钢管轻骨料混凝土构件的力学性能和相应的承载力计算方法等进行理论研究,并对其进行数值模拟,主要工作和结论有：1、运用统一强度理论,考虑中间主应力的影响,引入参数αu、βu确定薄壁钢管在极限荷载时的环向拉应力σθ,纵向压应力σz和径向压应力σr,并考虑轻骨料混凝土与普通混凝土多轴强度准则差异的影响,推导出圆形薄壁钢管轻骨料混凝土轴压短柱的极限承载力公式；考虑薄壁钢板的冷弯效应和有效宽度,采用等效截面方法推导出方形、八边形薄壁钢管轻骨料混凝土轴压短柱的极限承载力公式。将本文计算结果与文献试验数据进行比较,结果吻合良好,表明将统一强度理论运用于薄壁钢管轻骨料混凝土轴压短柱承载力计算是可行的。同时,本文推导公式只要合理的选择α、6和k的值,选用相应的屈服准则,就能适用于普通钢管轻骨料混凝土和自应力钢管轻骨料混凝土轴压短柱的承载力计算,为钢管轻骨料混凝土的优化设计提供了一定的理论依据。2、分析钢管混凝土粘结强度的基本机理,从理论上推导出钢管与混凝土界面间的粘结滑移本构关系；根据试验结果,通过线性统计回归得到了考虑长细比、径厚比、套箍指标等影响因素的薄壁钢管轻骨料混凝土极限粘结强度的计算公式。基于统一强度理论,考虑钢管混凝土界面间的粘结滑移作用,推导出薄壁钢管轻骨料混凝土轴压短柱承载力计算公式。通过理论计算可知粘结滑移作用对薄壁钢管轻骨料混凝土轴压短柱极限承载力的影响不显著。3、采用大型有限元分析软件ANSYS对薄壁钢管轻骨料混凝土轴压短柱的应力-应变关系曲线和应力云图进行了数值模拟,分析了套箍指标ξ和核心轻骨料混凝土强度等级对薄壁钢管轻骨料混凝土轴压短柱力学性能的影响。更多还原

【Abstract】 With the development of the modern civil engineering structure, the construction material and structure are higher required. As a new type of concrete filled steel tube, lightweight aggregate concrete filled thin-walled steel tube (LACFTST) has many advantages, such as high bearing capacity, fine plasticity and toughness, fire-resistant, seismic, excellent economic benefits and convenient construction and so on. The lightweight aggregate concrete filled thin-walled steel tube is widely used in the engineering construction, especially multi-story and low-rise buildings. However, little study has been done about its mechanical behavior. Related code or specification have not been complete, therefore, it is of great importance to investigate the mechanical performance of the short columns under axial pressure.In this paper, Mechanical analysis and calculation method of bearing capacity of the lightweight aggregate concrete filled thin-walled steel tube under axial load is carried out based on the unified strength theory, finite element simulation, the main contents are listed as follows:1. Based on the unified strength theory, considering the effects of the intermediate principal stress and the multi-axial strength criterion for the lightweight aggregate concrete, by introducing parameterαu andβu, loop tensile stressσθ, longitudinal compressive stressσz and radial compressive stressσr of ultimate bearing condition of the thin-walled steel is obtained. Thus the calculation formula of ultimate bearing capacity of short columns of the lightweight aggregate concrete filled thin-walled circular steel tube is deduced. The ultimate bearing capacities of short columns of the lightweight aggregate concrete filled thin-walled square or octagon steel tube are deduced by equivalent section method taking account of the effects of the cold curved effect and the effective width in thin-walled steel tube. Compared with the obtained solution and the test results in reference, good agreement can be found. The results indicate that the unified strength theory has the good applicability in the calculation of ultimate bearing capacity of short columns of the lightweight aggregate concrete filled thin-walled circular steel tube. Meanwhile, the various yield criteria can be obtained by varying the value ofα, b and k, so the formula can be applied to derive the ultimate bearing capacity of short columns of the lightweight aggregate concrete filled steel tube and the self-stress lightweight aggregate concrete filled steel tube. These solution can provide theoretical foundation for the design of the lightweight aggregate concrete filled steel tube.2. Based on the mechanism of bond between the steel tube and the concrete in the lightweight aggregate concrete filled thin-walled steel tube, the equation of stress of steel tube, bond stress, and relative slip btween steel tube and concrete are deduced through theoretical analyses. And the relationship of bond stress and slip is established. According to the test results and through statistics linear regression, the formula of ultimate bond strength of the lightweight aggregate concrete filled thin-walled steel tube is deduced by considering these factors (slenderness ratio, diameter-thickness ratio, confinement index, etc). The calculation formula of ultimate bearing capacity for short columns of the lightweight aggregate concrete filled thin-walled steel tube is deduced based on the unified strength theory. The effects of bond-slip behaviors of interface between the steel tube and the concrete is considered in the solution. The results indicate that the bond-slip behaviors has little influence on the ultimate bearing capacity of short columns of the lightweight aggregate concrete filled thin-walled steel tube.3. In this paper, the stress-strain curve and stress contour of the lightweight aggregate concrete filled thin-walled steel tube are obtained using the commercial finite element software ANSYS. In addition, the influences of the confinement index and the strength grade of core lightweight aggregate concrete on the mechanical performance of the short columns under axial pressure are discussed according to numerical results.更多还原