Experimental and numerical study of the ultimate load for collar-plate-reinforced tubular K-joints at fire-induced elevated temperatures.

The fire resistance of collar-plate-stiffened uniplanar tubular K-joints was studied and formulated in the present research. After establishing a finite element (FE) model and its verification against the results of experimental tests, a total of 1440 numerical simulations were performed on 360 FE models of collar-plate-stiffened uniplanar tubular K-joints at four different temperatures (20, 400, 550, and 700°C). The studied joints were analysed under the axial loading and the reinforcing effect of the collar plate was investigated. Results showed that the resistance enhancement coefficient (R_s) increases by increasing the γ, θ, and τ; while it decreases by rising the β. Results of the parametric investigation were utilised to establish new design equations to determine the bearing capacity of collar-plate-stiffened tubular K-joints under the brace axial loads at fire condition. [ABSTRACT FROM AUTHOR]