Fire-resistance industrial portal frames: design with different mechanical properties steels and 35 meters spans

Abstract

Various portal frames are studied to establish their fire response over various fire exposure times. The frames were assembled with plain carbon steel (S275) and micro-alloyed fire resistant (FR) steel (with superior fire-resistant properties). An intumescent fire protective paint was also tested to improve the overall fire resistance of the steel structure. In this paper, a dimensioning method is proposed that combines structural calculations with a conventional software package for the calculation of structural stress, in accordance with the geometric and elastic moduli of each complete section of the industrial metallic frame. The structure was sized by selecting the most economical combination and by estimating the stresses in each particular structural element or section of the overall structure. The process was then repeated with these new dimensions to reach the optimal structural design. The key variables analyzed in this study are: six fire-exposure times, seven intumescent paint thicknesses, and eleven price ratios between the FR and the S275 steels. Each structure in this study has a span of 35 m. The main conclusion is that the use of FR steel combined with S275 and an intumescent paint system is the most cost effective and technically feasible design option for industrial portal frames.