Parametric study and equations of the maximum SCF for concrete filled steel tubular T-joints under in-plane and out-of-plane bending.

Abstract Due to being increasingly used in infrastructure, studying stress concentration in concrete-filled steel tubular joints is necessary. In this study, the variation of the maximum Stress Concentration Factor (SCF max) with non-dimensional geometric parameters in steel circular hollow section brace welded to concrete-filled circular hollow section chord (CHS-to-CFCHS) T-joints under in-plane and out-of-plane bending moment has been investigated. A database of the maximum SCFs in CHS-to-CFCHS T-joints under in-plane and out-of-plane bending moment is developed based on three-dimensional (3D) finite element (FE) models. The 3D FE models developed using ABAQUS software, have been verified using experimental results. Graphs showing variation of the maximum SCF, in CHS-to-CFCHS T-joints, with non-dimensional geometric parameters have been produced and compared with those for non-filled empty T-joints. Parametric equations for predicting the maximum SCFs in CHS-to-CFCHS T-joints under in-plane and out-of-plane bending moment have been developed in a multiple nonlinear regression analysis. There is a good agreement between the maximum SCFs predicted by the parametric equations and those determined from the experiments. Highlights • The effect of the concrete infill in reducing the SCF max is moderate under in-plane bending and its effect is significant under out-of-plane bending. • Parameter β has very little effect on the SCF max under in-plane bending and has significant effect under out-of-plane bending. • The trend in variation of the SCF max under in-plane and out-of-plane bending with parameter τ in CHS-to-CFCHS T-joints is similar to that in empty T-joints yet its effect is less under out-of-plane bending in the CHS-to-CFCHS T-joints due to significant effect of the concrete infill. • The trend in variation of the SCF max under in-plane and out-of-plane bending with parameter γ in CHS-to-CFCHS T-joints is similar to that in empty T-joints yet its effect is less under out-of-plane bending in the CHS-to-CFCHS T-joints due to significant effect of the concrete infill. • Parameter α has no effect on the SCF max under out-of-plane bending. [ABSTRACT FROM AUTHOR]