Abstract Previously, a series of studies focusing on the response of the oval-ended elliptical concrete-filled steel tubular (OECFT) columns under various single load conditions were performed due to its novel superiorities in flow smoothness, architectural aesthetics and structural efficiency. Nonetheless, the properties of the OECFT column imposed with combined forces have never been addressed. In attempt to fill this gap, this paper aims to present a numerical analysis via ABAQUS solver to explore the torsional behaviour of the axially-loaded OECFT column. Following that, the finite element (FE) modelling was verified by the existing experimental data, and then the comprehensive parametric research on the type of column was conducted. Detailed responses of the OECFT column subjected to combined axial compression-torsion, in aspect of the typical torque ratio (T/Tu) – angle (θ) curve, failure patterns, contact action and characteristic relationship of relative ultimate torque value (Tu/Tu0) versus axial compression ratio (N/Nu0), were respectively investigated. The numerical simulation revealed that the torsional resistance of the type of column increased with the increase of the steel strength, concrete strength and steel ratio, while a decrease was obtained with the increase of the aspect ratio. Accompanied by the changes in axial compression ratio, material strength and steel ratio, obvious influences on the Tu/Tuo-N/Nuo curve were obtained. Finally, a design provision to assess the torsional strength of the OECFT column under combined axial compression-torsion was proposed and was validated in compliance with the aforementioned analyses.

中文翻译：

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组合轴压扭力作用下椭圆端椭圆CFT柱的性能与设计

摘要 此前，由于椭圆端椭圆钢管混凝土（OECFT）柱在流动流畅性、建筑美学和结构效率方面的新颖优势，在各种单一载荷条件下，对其响应进行了一系列研究。尽管如此，OECFT 柱在联合作用下的特性从未得到解决。为了填补这一空白，本文旨在通过 ABAQUS 求解器进行数值分析，以探索轴向加载的 OECFT 柱的扭转行为。随后，利用已有的实验数据对有限元（FE）建模进行了验证，然后对柱型进行了综合参数化研究。OECFT 柱在轴向压缩-扭转联合作用下的详细响应，在典型扭矩比（T/Tu）-角度（θ）曲线方面，分别研究了相对极限扭矩值（Tu/Tu0）与轴压比（N/Nu0）的失效模式、接触作用和特征关系. 数值模拟表明，该型柱的抗扭强度随着钢强度、混凝土强度和钢比的增加而增加，而随着纵横比的增加而降低。伴随着轴压比、材料强度和钢比的变化，对Tu/Tuo-N/Nuo曲线的影响明显。最后，提出了评估 OECFT 柱在轴向压缩 - 扭转组合下的扭转强度的设计规定，并根据上述分析进行了验证。