Numerical models and parametric study on ultimate strength of CHS T-joints subjected to brace axial compression under fire condition

This paper presents a parametric study on ultimate strength of Circular Hollow Section (CHS) T-joints under fire condition using Finite Element (FE) models. The models of the CHS T-joints subjected to brace axial compression were created using ABAQUS v6.7-1. The FE models were first validated with test results. The parametric study was then carried out with four parameters which directly affect the ultimate strength of the T-joints. The four parameters are boundary condition, precompression in the chord, chord length, and chord thickness. This parametric study aimed to find out the sensitivity of each parameter due to changes of temperature as well as to establish a CHS T-joint ultimate strength database at high temperature. It was found that as temperature increased, the difference between "pinned-end" and "fixed-end" conditions becomes more significant. Elevated temperature also results in an increase of the reduction factor for T-joints subjected to pre-compression in the chord. The same effect was found for T-joints with different chord lengths. A rise in temperature will change the failure mode and load-moment interaction. However, the effect of chord thickness to ultimate strength of the joints was independent of the rise of temperature.