General Parametric Design Equations for SCFs in Steel, Multiplanar Tubular XT-Joints

This paper concentrates on the parametric stress analysis of steel, multiplanar tubular XT-joints using the finite element (FE) method. An extensive database of stress concentration factors (SCFs) at fixed hotspot stress locations was built by carrying out about 600 runs of FE analysis on 84 XT-joint models covering a wide range of geometrical parameters. Nine different load cases of basic brace and chord axial, in-plane-bending (IPB) and out-of-plane-bending (OPB) moments were considered Through parametric study, a new set of SCF design equations were established for general end load conditions. The new definition of the hotspot stress (HSS) from the latest research findings was adopted. This allowed the use of the superposition method of these equations to predict the HSS of multiplanar tubular XT-joints under any arbitrary combinations of brace and chord end loads. In addition, an assessment of these parametric equations was carried out using the latest acceptance criteria from the UK Department of Energy (DOE), and the study confirmed the accuracy and reliability of the proposed equations.

S.P. Chiew, C.K. Soh and N.W. Wu