Axial Compression Test and Numerical Investigation of Concrete-Filled Double-Skin Elliptical Tubular Short Columns

To probe into the performance of concrete-filled double-skin elliptical steel tubular (CFDEST) members, this paper designs and conducts an experiment on CFDEST short columns imposed with axial pressure, and finite element (FE) models of the axially compressed CFDEST stub columns are established and verified by the test outcomes, taking the influences of elliptical cross-section and hollow ratio into account. The impressions of various parameters, such as hollow ratio, diameter-to-thickness ratio, aspect ratio and so on, on the load-bearing capacity, initial rigidity and ductility property were investigated systematically. Moreover, the typical failure modes, contact pressure and concrete longitudinal stress of the axially compressed CFDEST short column are revealed. In light of the findings acquired by the laboratory tests and numerical analyses, the calculation formulae for evaluating the axial compress capacity of the CFDEST short column are proposed by taking the impact of the sectional aspect ratio and hollow ratio into account. The results indicate that the failure morphologies of axially compressed CFDEST short columns mainly include outward local bulges of the outside EST, the inward bulges of the inside EST and the crushing of core concrete. The axial compress capacity of the CFDEST short column would increase with the decrease in the sectional hollow ratio and aspect ratio. The calculation method is proved to be an accurate and reliable approach to evaluate the axial compress capacity of the CFDEST short column.