Elevated temperature material behaviour of high-strength steel

This paper presents an experimental investigation into the behaviour of high-strength steel (HSS) structures (i.e. yield strength between 460 and 700 N/mm(2)) in fire conditions. The paper proceeds with a description of the experimental programme that includes two different grades of HSS with the aim of assessing (a) the mechanical properties at elevated temperature through tensile testing and (b) the effect of chemical composition and processing route on the microstructure through a detailed metallurgical investigation. The investigation takes a holistic view of the analysis whereby the effect of processing route and composition on the microstructure and hence mechanical properties are assessed. In this paper, following a detailed description of the tests under isothermal conditions, the results are analysed to determine strength and stiffness reduction factors at elevated temperatures and these values are compared with the literature and design standards.