The shear strength parameters (i.e., the internal friction coefficient f and cohesion c) are very important in rock engineering, especially for the stability analysis and reinforcement design of slopes and underground caverns. In this paper, a probabilistic method, Copula‐based method, is proposed for estimating the shear strength parameters of rock mass. The optimal Copula functions between rock mass quality Q and f, Q and c for the marbles are established based on the correlation analyses of the results of 12 sets of in situ tests in the exploration adits of Jinping I‐Stage Hydropower Station. Although the Copula functions are derived from the in situ tests for the marbles, they can be extended to be applied to other types of rock mass with similar geological and mechanical properties. For another 9 sets of in situ tests as an extensional application, by comparison with the results from Hoek‐Brown criterion, the estimated values of f and c from the Copula‐based method achieve better accuracy. Therefore, the proposed Copula‐based method is an effective tool in estimating rock strength parameters.

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%.