Effect of strengthening methods on eccentric compression of rubber concrete‐filled double‐skin columns

Rubberized concrete‐filled double‐skin steel tubes (RCFDST) combine lightweight construction, superior deformability, and eco‐friendly use of scrap tire rubber. This study aims to investigate the eccentric compression behavior of rubber concrete‐filled double‐skin tubular members reinforced by three different methods: no reinforcement, welded reinforcement rings at the ends, uniformly welded reinforcement nails on the outer surface of the inner tube. The impact of these three reinforcement strategies on the performance of RCFDST columns subjected to eccentric compression tests is discussed. A comparison of ultimate strength, lateral displacement, and other parameters between RCFDST columns and concrete‐filled double‐skin tubular columns is presented. The reliability of the experimental results was confirmed using ABAQUS finite element methods. The results show that the addition of a welded steel reinforcement ring at the extremity increases the eccentric compression bearing capacity of RCFDST by 6.8% with only a minor increase in steel use of 2.3%. This method allows the member to achieve strength comparable to that of conventional concrete‐filled double‐skin tubular members. Furthermore, the strategy of uniformly distributing reinforcement along the outer wall of the inner steel pipe promotes synergistic deformation between the interlayer rubberized concrete and the structural member, significantly reducing lateral deformation of the member, including a 144% reduction in lateral deflection at the center at ultimate load capacity and a 5.9% reduction in end test lateral displacement.