Stress concentration factors of RHS T-connections with galvanizing holes under in-plane bending

Abstract

The hot spot stress method recommended by the CIDECT Design Guide 8 cannot be directly used in the fatigue design of galvanized tubular steel connections since: (1) the hot-dipping process can sometimes significantly change the residual stress magnitude and distribution at the welded joint; and (2) sufficiently large vent and drain holes must be specified at the welded joint location prior to galvanizing, and quite often at the locations recommended by the design guide for calculation of hot spot stresses. Hence, the existing formulae and charts for determination of Stress Concentration Factors (SCFs) may not be applicable. In this study, Finite Element (FE) modelling was performed to examine the existing SCF formulae for welded rectangular hollow section (RHS) T-connections under brace in-plane bending. The FE models were validated by comparison of the experimental results from six large-scale connection tests. A parametric study including 192 FE models with varied hole locations, brace-to-chord width ratios, chord wall slendernesses, and brace-to-chord thickness ratios, shows that the existing SCF formulae can lead to unsafe predictions. Critical hot spot stress locations are thus identified. The effects of both brace in-plane bending and chord loading were studied. New design formulae that take the vent and drain holes into account are proposed. These formulae are shown to provide more accurate predictions of SCFs in such connections.