中空夹层椭圆钢管混凝土短柱轴压性能试验与数值分析

中空夹层椭圆钢管混凝土(concrete-filled double-skin elliptical steel tubular, CFDEST)造型独特、性能优良，在实际工程中逐渐被采用，但其力学性能研究较少，文章设计和开展6根CFDEST短柱的轴压试验，建立基于椭圆截面特征和空心率影响的CFDEST轴压短柱的分析模型，研究空心率、材料强度、径厚比和截面长短轴比等参数对其承载力、刚度和延性等力学性能指标的影响规律，揭示CFDEST短柱在轴压作用下的典型破坏形态、截面应力分布和环向接触行为。结果表明：CFDEST轴压短柱的破坏模式主要包括钢管局部腰鼓屈曲和剪切屈曲、核心混凝土局部压溃和斜向剪切破坏；轴压承载力随着空心率和径厚比的减小而增大，随着钢材强度和混凝土强度的增大而增大。

Concrete-filled double-skin elliptical steel tubular (CFDEST) members are characterized by their unique shapes and excellent performance, leading to growing adoption in practical engineering. However, their mechanical properties are less studied. In this paper, axial compression tests on six CFDEST short columns were designed and carried out, and a numerical analysis model of axially-loaded CFDEST short columns considering the influence of elliptical section characteristics and hollow ratio was established based on the test findings. The influence of the parameters including hollow ratio, material strength, diameter-to-thickness ratio and cross-sectional aspect ratio on the mechanical performance indexes such as bearing capacity, stiffness and ductility was investigated, and the typical failure pattern, cross-sectional stress distribution and circumferential contact behavior of CFDEST short columns under axial compression were revealed. The results show that the failure modes of axially-loaded CFDEST short columns mainly include steel pipe local waist bulge buckling and shear buckling, core concrete local crush and oblique shear damage; the axial compression bearing capacity of CFDEST short columns increases with the decrease of hollow ratio and diameter-to-thickness ratio, and the increase of steel strength and concrete strength.