Behaviour and design of stainless steel structures in fire

Owing to its unique combination of excellent corrosion resistance, low maintenance requirements and high performance in fire and under impact loading, stainless steel manifests itself an appropriate and advantageous construction material for projects where corrosion resistance, durability, maintenance costs or resistance to fire or extreme loading are of importance. Stainless steel is also highly recyclable and reusable, making it a sustainable construction material. Traditionally, due to its initial high material cost, stainless steel has been regarded as an option limited to specialist and prestige applications. However, with increased awareness on whole life-cycle costing and sustainability, rather than simply initial expenditure, the use of stainless steel in the construction and offshore industries has been increasing.

At elevated temperatures, stainless steel displays higher strength and stiffness retention relative to carbon steel with different material stress-strain response, leading to considerably enhanced structural performance for stainless steel structural elements relative to those made of carbon steel in fire. However, thus far, this high performance of stainless steel structural elements in fire has been neither scientifically well explored, nor has a design guidance leading to its efficient exploitation been developed. In fact, the current British and European structural steel fire design standard Eurocode 3 Part 1.2 recommends the design methods originally developed for carbon steel members for the fire design of stainless steel structural members. This unsurprisingly leads to very inaccurate estimations of the response of stainless steel structures in fire, precluding the efficient use of their high performance at elevated temperatures by structural engineers in practice. For projects where thermal protection is not used to showcase the attractive appearance of stainless steel, inefficient fire design rules, which may govern cross-section sizes, lead to excessive material use and thus very uneconomic solutions.

With the aim of achieving a step-change in understanding the response of stainless steel structural elements at elevated temperatures and in their fire design, the proposed research will involve comprehensive numerical studies on the behaviour of stainless steel structural elements in fire and lead to the development of statistically validated design guidance able to exploit the high performance of stainless steel structures at elevated temperatures. The proposed research will not only consider structural elements made of traditional stainless steel grades but also those made of a number of novel, cost-effective and high performance stainless steel grades recently introduced into the market for structural engineering applications; for the first time, elevated temperature material tests will be carried out on these stainless steel grades in this project. Possessing a number of novel aspects such as involving the first comprehensive investigations on the response of stainless steel plates, sections, columns and beams in fire and the elevated temperature material tests on new stainless steel grades whose elevated temperature material properties are unknown, it is envisaged that the proposed project will fill an important gap of knowledge with respect to the behaviour and design of stainless steel structures in fire. In this project, all the design guidance will be prepared adopting the Eurocode 3 Part 1.2 philosophy; it is anticipated that the project will generate design methods suitable for incorporation into the future versions of Eurocode 3 Part 1.2.