Research on axial compressive behavior of lightweight concrete-filled cold-formed elliptical hollow section steel stub columns

Abstract

为研究由热轧圆钢管冷拔成型的椭圆钢管短柱的轴压性能,分别对空腹和填充轻骨料混凝土的椭圆钢管短柱进行试验,分析椭圆钢管和轻骨料混凝土的材料性能以及短柱试件的承载能力、破坏模式、延性等。结果表明:与母材热轧圆钢管相比,冷拔成型椭圆钢管短柱表现出较低的承载力和延性;填充轻骨料混凝土能够显著提高试件的承载力和延性;相比于椭圆钢管短柱,填充混凝土对圆钢管短柱轴压承载力和延性提高程度大,且壁厚小的试件轴压承载力和延性的提高程度大(约10%);通过与国内外相关设计规范计算结果的对比,现行针对热处理椭圆钢管短柱承载能力计算方法可用于冷成型椭圆钢管短柱承载能力计算,EC4规范可以较准确的估计圆钢管混凝土试件的承载能力,我国CECS 28:2012钢管混凝土结构技术规程适用于壁厚较小的冷成型椭圆钢管混凝土短柱轴压承载力计算,壁厚较大的冷成型椭圆钢管混凝土短柱轴压承载力计算方法有待进一步研究。 To study the axial compression performance of elliptical steel tubular stub column, this paper presents an experimental investigation on lightweight concrete-filled circular and elliptical hollow section steel tubular columns under axial compression at cross-section level. The lightweight aggregate concrete and elliptical tube material properties, bearing capacity, failure mode and ductility of stub column were analyzed. The elliptical hollow section (EHS) was cold-formed from the hot-rolled circular hollow section (CHS). Comparison based on experimental findings in particular between the hot-rolled CHS and cold-formed EHS were made. The results indicate the cold-forming process reduces the load carrying capacity and ductility; being filled with concrete can significantly improve the bearing capacity and ductility of stub column; contribution of filling concrete is larger in the concrete-filled hot-rolled CHS stub columns than that in the concrete-filled cold-formed EHS stub columns; the level of enhancement due to concrete in-filling is more significant for the thinner EHS and CHS tubes (about 10%). Design rules based on Chinese and foreign standards were also assessed: the prediction of cold-formed EHS compressive resistance based on the hot-finished formulations is adequate; design equations based on Eurocode 4 can be adopted for the lightweight concrete-filled hot-rolled circular hollow sections; CECS 28-2012, the code for design of concrete-filled steel tubular structures can be used for the compressive bearing capacity calculation of thinner lightweight concrete-filled EHS, but the compressive bearing capacity calculation method for thicker lightweight concrete-filled EHS needs further study.