Study on Strengthening of Concrete Filled Double Skin Tubular Columns with Lateral Intermittent Weld Reinforcing

This study presents an experimental investigation along with the development of a finite element model (FEM). Determine the ultimate strength of concrete-filled double-skin tubular (CFDST) short columns. The primary focus is on assessing the axial strength of CFDST specimens, analyzing load- displacement behavior, deformation characteristics, and ultimate load capacity. The experimental findings revealed that the distribution of internal forces significantly influenced the effective confinement area of the concrete, which, in turn, affected the ultimate load capacity. This insight into force distribution provides a theoretical basis for calculating the confinement area used in both the FEM and the proposed design model. A nonlinear finite element model was developed using ANSYS to accurately replicate the behavior of the CFDST columns under axial loading. The FEM was validated against experimental results. Based on the analysis, a new design model was proposed, which takes into account the effective cross-sectional area of the confined concrete. The strength predictions generated by this design model closely matched the experimental results, confirming its reliability for practical engineering applications.