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Abstract

It is common practice in the industrial sector to leave the top flanges of fireproofed beams bare. The main reason for this is to permit placement of pipes and grating on the beams without interference from fireproofing materials. To the authors' knowledge, tests of such configurations have not been conducted to determine actual resistance to fire. However, structures fireproofed in this manner have survived actual fire exposures. The purpose of this paper is to examine theoretically the effect of various fireproofing designs on the performance of these members and point out which practices can lead to premature failure of fireproofed beams where top surfaces are left bare. An approximate but practical analytical model is used to evaluate bare steel, encased (concrete/contour) and box (hollow) constructions. The need for reinforcements is demonstrated by examining the effect of bond loss in decomposable systems. Thermal performance is related to load carrying capability of the member.