This study investigates the stress mechanism and bearing performance of a novel composite column comprising a pultruded GFRP tube, concrete, and a steel tube. Thirteen composite column specimens were fabricated with varying parameters, including GFRP tube thickness, concrete strength, cross-sectional hollowness ratio, steel tube thickness, number of shear stud layers, and cross-sectional form. Axial compressive tests were conducted to assess the bearing capacity of the composite columns. The results indicate three typical failure modes for the double-skin tube composite (DSTC) specimens. Additionally, increasing the number of shear stud layers enhances the bearing capacity of the DSTC specimens. Based on the test results and the limit equilibrium theory, a bearing capacity calculation formula for the composite column was derived, with the computed results aligning well with the experimental findings.
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