方钢管型钢再生混凝土组合柱轴压性能试验研究

Experimental investigation on axial compression performance of recycled aggregate concrete filled square steel tube-profile steel composite columns

为研究方钢管型钢再生混凝土组合柱轴压性能,设置了长细比、再生骨料取代率、再生混凝土强度、型钢配钢率和方钢管宽厚比等参数,对13个试件进行单调静力加载试验,观察试件破坏过程及破坏形态,获取试件荷载-位移和荷载-应变曲线,分析设计参数对组合柱轴压受力性能的影响。结果表明:试件的破坏顺序均为型钢首先被压屈,随后再生混凝土被压碎,最后的破坏是因为钢管外表面发生鼓屈而丧失轴压承载力;提高长细比、钢管宽厚比和再生粗骨料取代率,组合柱轴压承载力的最大降幅分别为10.7%、24.8%和9.9%;相反,提高再生混凝土强度和型钢配钢率,组合柱的轴压承载力最大提高幅度分别为19.7%和14.3%;总体上看,试件均表现出较高的承载力和良好的变形能力。在此基础上,参考国内外相关规程,采用叠加原理,建立了方钢管型钢再生混凝土组合柱的轴压承载力公式,并验证了计算公式的有效性。

In order to study the axial compression performance of recycled concrete filled square steel tube-profile steel composite columns, 13 specimens are tested under monotonic static loading. In the tests, the major variable parameters include the slenderness ratio, recycled coarse aggregate (RCA) replacement percentage, recycled concrete strength, steel reinforced ratio, and the width to thickness ratio of steel tube. The failure process and mode of all specimens are observed, and the load-displacement curves and the load-strain curves are also obtained. The influence of design parameters on the axial compressive behavior of the specimens is analyzed. The results indicate that the axial compressive process and failure mode of all specimens are similar. The internal profile steel yields before the external steel tube, then the core recycled concrete is crushed, and ultimately the square steel tube buckling leads to the loss of load-bearing capacity and failure of the specimens. With increasing the slenderness ratio, the width to thickness ratio and recycled coarse aggregate replacement percentage, the maximum decreasing values of axial bearing capacity of specimens are 10.7%, 24.8% and 9.9%, respectively. With increasing the recycled concrete strength and steel ratio, the maximum increasing values of axial compressive capacity are 19.7% and 14.3%, respectively. On the whole, the specimens show high bearing capacity and favorable deformation ability. Moreover, by referring to the relevant domestic and international regulations, the calculation formula on the axial bearing capacity of square steel tube steel reinforced recycled concrete composite columns are established by the superposition principle. Meanwhile, the validity of the calculation formula is verified.