Hot spot stress concentration factor of CFST T/Y joints based on modified equivalent thickness

Abstract

To extend the calculation method of hot spot stress concentration factors (SCFs) of circular hollow section (CHS) joints in concrete-filled steel tubular (CFST) joints, a calculation method of SCFs of CFST T/Y joints based on the modified equivalent thickness is proposed. Considering the contact relationship between the concrete and tubular wall and the axial force acting on the CFST chord, 36 finite element models of the CFST T/Y joint were established with different geometric parameters, and the stress distribution of the CFST chords and the CHS braces were investigated. According to the SCFs formula of grouted chord joints given by DNV, the modified equivalent thickness of CFST T/Y joints is derived based on the parametric FEA results. The modified calculation method of SCFs of CFST T/Y joints was established based on the modified equivalent thickness and CIDECT formulas. the proposed SCFs formulas for the CFST T/Y joints were verified by FEA and the experiment results with a calculation error of 20%.