High strength steel in fire

High-performance materials are necessary to meet the future demands of the construction industry, which is strongly influenced by a growing population and depletion of natural resources. Sustainable development is central to research and development into innovative structural materials, and requires solutions to be economically viable whilst equally providing a positive contribution towards environmental and social factors. High strength steels (HSS) have the potential to contribute towards such demands by reducing the weight of structures when employed in appropriate applications. Lighter structures require smaller foundations, shorter transportation and construction times and also lower CO2 emissions. A particular challenge related to the use of HSS in structures include increased likelihood of stability issues resulting from the reduction in section thickness, and limiting deflection and vibration criteria are also more likely to be critical. Nevertheless, when used appropriately, they can provide a sustainable solution. Their use in structural applications is further hindered by a lack of performance data and design guidance under fire conditions. This paper compares the mechanical properties, particularly strength and stiffness of HSS (yield strengths between 460-700 MPa) and mild steel (yields between 235-460 MPa) at elevated temperatures, through a critical review of published literature. Various alloying and processing routes used to achieve high yield strength are assessed. At the same time, the review considers available information on the strengthening mechanisms that can be utilised to retain the strength and/or stiffness of the material in the event of a fire. Using the information gathered, an extensive testing programme is developed which will enable design guidance for the fire design of HSS structures to be proposed.Engineering and Physical Sciences Research Council, TW

Behaviour of High Strength Steel under Fire Conditions

This paper is concerned with the material characteristics of various commercial high strength structural steels (yield strengths between 460 and 700 N/mm2) at elevated temperatures. These steels vary in chemical composition and production route but have similar tensile properties at ambient temperature. Preliminary data of the following: proportional limit (fp,θ), elastic modulus (Ea,θ), effective yield strength (fy,θ) based on the total strain level at 2% (in accordance with the Eurocode approach) obtained from isothermal tests are presented as reduction factors and compared with literature and the Eurocode (EN 1993-1-2). The consequences for material selection and design are also discussed.The authors would like to acknowledge the EPSRC and TWI Ltd. for the financial support provided for this work through an Industrial CASE award scheme

Flexural buckling behaviour of high strength steel columns under fire conditions

EPSRC; TWI Lt