Behaviour and design of stainless steel structures in fire

由于不锈钢具有优异的耐腐蚀性、低维护要求和在火灾和冲击载荷下的高性能的独特组合，因此对于耐腐蚀性、耐久性、维护成本或耐火或极端载荷非常重要的项目来说，不锈钢是一种合适和有利的建筑材料。不锈钢也是高度可回收和可重复使用的，使其成为一种可持续发展的建筑材料。传统上，由于不锈钢的初始材料成本较高，一直被认为是仅限于专业和有声望的应用的选择。然而，随着人们对整个生命周期成本计算和可持续性的认识不断提高，而不仅仅是最初的支出，建筑和近海行业中不锈钢的使用量一直在增加。在高温下，不锈钢相对于碳钢表现出更高的强度和刚度保持率，具有不同的材料应力-应变响应，导致不锈钢结构构件的结构性能相对于碳钢在火灾中的结构性能有显著提高。然而，到目前为止，这种高性能的不锈钢结构构件在火灾中既没有得到科学的很好的开发，也没有制定出能够有效利用它的设计指南。事实上，英国和欧洲现行的结构钢防火设计标准欧洲规范3第1.2部分推荐了最初为碳钢构件开发的设计方法，用于不锈钢结构构件的防火设计。不出所料，这导致了对不锈钢结构在火灾中的反应的非常不准确的估计，使得结构工程师在实践中无法有效地利用它们在高温下的高性能。对于不使用热保护来展示不锈钢外观的项目，低效的防火设计规则可能会管理横截面尺寸，导致过度使用材料，从而导致非常不经济的解决方案。为了在理解不锈钢结构元件在高温下的反应及其火灾设计方面取得阶段性变化，拟议的研究将涉及对不锈钢结构元件在火灾中的行为进行全面的数值研究，并导致开发能够利用不锈钢结构在高温下的高性能的统计验证设计指南。拟议的研究将不仅考虑由传统不锈钢牌号制成的结构元件，还将考虑由最近引入市场用于结构工程应用的一些新的、具有成本效益的高性能不锈钢牌号制成的结构元件；在本项目中，将首次对这些不锈钢牌号进行高温材料试验。由于具有许多新的方面，例如首次全面调查不锈钢板、型材、柱和梁在火灾中的反应，以及对高温材料性能未知的新不锈钢牌号进行高温材料试验，预计拟议的项目将填补有关不锈钢结构在火灾中的行为和设计的重要知识空白。在该项目中，所有设计指南将采用欧洲代码3第1.2部分的理念编写；预计该项目将生成适合纳入欧洲代码3第1.2部分未来版本的设计方法。

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.