外方内圆复合钢管混凝土抗弯性能及承载力实用计算

Flexural Behavior and Practical Calculation of Load Bearing Capacity for Compositesectioned Square Concrete Filled Steel Tube Reinforced by Inner Circular Steel Tube

对外方内圆复合钢管混凝土的纯弯力学性能进行了有限元模拟,计算结果得到试验结果的验证。在此基础上,进行了荷载-变形全过程受力分析和影响因素分析,基于钢管混凝土简单叠加方法,引入组合提高系数,提出了外方内圆复合钢管混凝土抗弯承载力实用计算公式。研究结果表明,外方内圆复合钢管混凝土抗弯承载力比简单叠加结果大,其组合提高系数的主要影响因数是外管屈服强度、夹层混凝土抗压强度和内外管尺寸比,且该系数随着外管屈服强度的增加、内外管尺寸比的增加而增加,随着夹层混凝土抗压强度的降低而增加;抗弯承载力简化计算结果与实测结果和有限元结果吻合良好,且总体稍偏于安全。

The flexural behavior of composite-sectioned square concrete filled steel tube reinforced by inner circular steel tube is simulated by finite element method. The calculated results are validated by the experimental results.Furthermore,the whole mechanical characteristics of load-deformation curve and parameter influence of the composite-sectioned members are analyzed. Based on the simple additive rule of concrete filled steel tubes,a composite increased coefficient is introduced and the practical calculation formula on flexural load bearing capacity of this kind of composite members is proposed. The results show that,the flexural load bearing capacities of composite-sectioned square concrete filled steel tubes reinforced by inner circular steel tube are higher than the results predicted by the simple additive rule. The main parameters influencing the composite increased coefficient are strength of outer tube,compressive strength of sandwich concrete and the dimension ratio of inner tube to outer tube. With the increase of outer tube strength,the dimension ratio of inner tube to outer tube or the decrease of sandwich concrete compressive strength,the composite coefficient increases. The flexural load bearing capacities calculated by the simplified calculation formula agree well with the finite element results and they show a tendency to safe as a whole.