Abstract:

This study aims to investigate the post-fire behavior of truss system T-joints made of pipe or box profiles under axial load using the finite element method. Hence, T-joints with different geometrical properties were modeled using the finite element program. First of all, heat transfer analysis was performed and the numerical models were heated based on the ISO 834 fire curve and then the joints were cooled. An axial load was applied from the end of the brace member to the joints, which were exposed to residual stresses and deformations after the fire, until they reached the maximum capacity. Each joint was failed due to plastification on the wall of the chord member. The strengths of the joints before and after the fire were compared. According to the findings obtained from the numerical results, the strength of tubular T-joints after fire decreases to up to 23.5%. In addition, the temperature distributions on the joints vary depending on the brace-to-chord member ratios and chord wall thicknesses. Residual stress and deformations after fire have a significant effect on the strength of both pipe and box T-joints.

Keywords: