Behavior of T and X joints of elliptical hollow sections at both ambient and high temperatures

This paper presents the results of a numerical study to develop a method to calculate the ultimate load carrying capacity of welded Elliptical Hollow Section (EHS) joints at elevated temperatures. Extensive numerical simulations, using the non-linear finite element package ABAQUS v6.14-1, have been conducted on EHS T-and X-joints subjected to brace axial compression or tension, considering a wide range of geometrical parameters, pre-stress in chord member and different type of joint orientations. The FE simulation results indicates that the equivalent RHS method is not appropriate for calculating the load carrying capacity of EHS joints at ambient temperature. At elevated temperatures, for T-and X-joints with braces welded to wide sides of chord, replacing the ambient temperature yield strength of steel by the elevated temperature value overestimates the ultimate load carrying capacity of axially loaded EHS T-and X-joints with compressive brace. Alternative design methods have been proposed.