A new type of stiffening rib is proposed to improve the mechanical performance of T-shaped concrete-filled steel tubular (CFST) columns. A finite element model was established using the general-purpose commercial software ABAQUS 2022. After verification through comparison with experimental data, the developed finite element model was employed to numerically evaluate the performance of T-shaped CFST short columns with stiffening ribs under axial compression. The results indicated that the new stiffening ribs are capable of significantly reducing the buckling deformation of the steel tube, enhancing the confinement effect of the steel tube on the core concrete, and improving the combined performance of the steel tube and the concrete. The thickness and material strength of the stiffening ribs had a notable impact on the ultimate bearing capacity and ductility of the short column specimens. When the thickness of the stiffening ribs increased from 5 mm to 8 mm, the ultimate bearing capacity correspondingly increased by 10.51% to 31.77%, while the ductility coefficient improved by 6.48% to 17.20%. When the steel strength increased from 262.50 MPa to 345 MPa and 390 MPa, the ultimate bearing capacity correspondingly increased by 17.36%, 19.78%, and 30.50%, and the ductility coefficient improved by 12%, 13.87% and 23.92%. The changes in the specifications and arrangement of the stiffening ribs had no significant effect on the ultimate bearing capacity and ductility of the specimens. The change in angle steel specifications caused variations in ultimate bearing capacity within ±5% and variations in the ductility coefficient within ±10%. Changes in the arrangement caused variations in ultimate bearing capacity within ±1% and variations in the ductility coefficient within ±5%.

The bond between steel bars and concrete is a fundamental aspect of reinforced concrete, ensuring the efficient transfer of forces between the two materials and guaranteeing their compatibility and composite action. The conventional equation for calculating bond stress does not account for slip effects. However, significant slip can lead to considerable errors, which are disadvantageous when analyzing bond performance using finite element methods. To address this issue, this study proposed a modified bond stress calculation model, whose reliability was systematically validated through pull-out tests and comparative analysis with a CEB-FIP model. The experimental program employed a universal testing machine for load application, with a static strain measurement system continuously monitoring stress–strain data throughout the loading process. The experimental results indicated that the failure process of the specimens could be categorized into the following, four distinct stages: micro-slip stage, slip stage, descent stage, and residual stage. The discrepancy between bond stresses calculated by the modified and conventional equations increased with the increasing relative slip, reaching its maximum value in the residual stage. A comparative analysis of 23 groups of experimental data from the literature was performed, revealing that the difference in bonding stress reached a maximum of 20.45% in the residual stage, with a standard deviation (S) of 0.006 and a coefficient of variation (C_v) of 0.321, reflecting small fluctuations but large dispersion. In contrast, the S of the residual bonding stress was 0.016, and the C_v was 0.080, showing lower dispersion but greater volatility. Further comparison with the CEB-FIP model confirmed the superior applicability and computational accuracy of the proposed modified model. Therefore, the modified equation should be utilized for calculating bond stress when significant slip occurs, particularly during the residual stage.