Stainless steel structures in fire

Abstract

The initial material cost of structural stainless steel is about four times that of structural carbon steel, due largely to the expense of the alloying elements and the relatively low volume of production. Given broadly similar structural performance, additional areas of benefit need to be identified and exploited in order to establish stainless steel as a viable alternative material for construction. In addition to the familiar benefits of corrosion resistance, low maintenance, high residual value and aesthetics, one such area is fire resistance. Material properties and their response to elevated temperatures form an essential part of structural fire design. The mechanical and thermal properties of stainless steel differ from those of carbon steel due to variation in chemical composition between the materials. A comparison of these properties for austenitic stainless steel with those for structural carbon steel is presented in this thesis, and implications of the differences explored. A total of 23 column buckling tests, 6 stub column tests, 5 simply supported beams, 1 continuous beam and 14 temperature development tests have previously been conducted on stainless steel sections in fire. These tests have been replicated numerically using the non-linear finite element package ABAQUS. Following accurate replication of the tests, a series of parametric studies were performed to expand the range of available data. Based on comparisons between all available test data and the current design rules in Eurocode 3: Part 1.2, together with the findings of the numerical study, a number of revisions to the code have been proposed. They include revised values for the heat transfer coefficient and emissivity, revised buckling curve, consistent strain limits and a new approach to the treatment of cross- section classification and local buckling. These revisions have led to a more accurate determination of temperature development in structural stainless steel, and provide more efficient and more consistent treatment of buckling of stainless steel structures in fire.