Modelling the post‐fire material behaviour of high‐ and ultra‐high‐strength steels

Abstract High‐strength steels can contribute to more sustainable and resource‐efficient constructions; for example, they can result in material savings due to the possibility of using smaller cross‐sectional dimensions. However, for a reliable assessment of the residual load‐bearing capacity of high‐strength steel components after a fire, there are still a lack of sound models on the post‐fire material behaviour of high‐strength steels, so high‐strength steel components are usually replaced after a fire. The question is whether this is always necessary. This paper presents the development of an application‐oriented material model for the determination of relevant mechanical material properties of high‐ and ultra‐high‐strength steels in the post‐fire range. The model is developed and statistically validated based on comprehensive studies of experimental results of post‐fire tensile tests on various high‐ and ultra‐high‐strength steels. The study thus provides the basis for reliable structural designs and future normative guidance for fire engineering practice.