Fire-Resistance Design Method for Stainless Steel Tubular X-Joints

Abstract

An experimental study was carried out on the fire-resistant performance of six stainless steel tubular X-joints. The failure process and behavioral responses of all specimens were determined, and the failure criteria of stainless steel tubular X-joints at elevated temperatures was developed. Numerical simulation was performed of the stainless steel tubular X-joints subjected to fire, and the accuracy of the model was verified by comparison with the experimental results. By referring to the yield line model in the existing specifications, a yield line model that simultaneously considers the deformation of the chord flange and web was established for stainless steel tubular X-joints. Through theoretical derivation and fitting, the prediction formula of failure temperature for stainless steel tubular X-joints without considering the effect of chord preload was obtained and then modified with the finite-element results. The adverse effect of chord preload on the failure temperature of tubular X-joint was explored using parametric analysis, and the expression of the reduction factor of failure temperature for stainless steel tubular X-joints under chord preload was obtained. A fire-resistance design method for stainless steel tubular X-joints under chord preload is proposed.