Structural behaviour of high strength S690 cold-formed square hollow sections under compression

Abstract

Motivation: Compared with normal strength steels, high strength steels have remarkable advantages in construction, due to their high resistances per unit weight of the materials. Structural hollow sections have been widely applied in steel construction all over the world because of their high resistances against instability and their highly desirable architectural appearance. In general, fabrication of hot-finished structural hollow sections always requires a huge amount of initial capital investment, and it is only financially viable to produce many thousand tons of standard sections. In recent years, cold-formed square hollow sections (CFSHS) become very popular because of their low set-up costs even to produce several hundred tons of non-standard sections. These CFSHS are readily fabricated with a combination of transverse bending and longitudinal welding in many modern fabricators. It should be noted that these two fabrication processes will impose significant effects onto the structural performance of these sections which are very different to those of hot-finished structural hollow sections. Currently, applications of high strength steel CFSHS are rather limited due to a lack of understanding on their structural behaviour as well as a lack of effective design rules.