Computational evaluation of limit states of thin-walled channels made from steel foam

Abstract

The objective of this paper is to explore the potential strength and serviceability implications of metallic foams, specifically steel foam, utilized as a thin-walled channel structural member. A typical advantage sought in the selection of a thin-walled member is minimal weight. However, the stability of the thin walls and the related limit states constrains the extent to which weight minimization may be utilized. As a material, steel foam (literally creating air voids in the steel microstructure) offers the potential to provide increased plate stiffness for a given weight and thus create even lighter thin-walled members and structures. In this work analytical material relationships are used to explore the structural potential for steel foam. First, the local buckling and yielding of an isolated steel foam plate is explored. Second, the local, distortional, and global buckling of a prototypical cold-formed steel channel using steel foam is examined. Finally, the strength and governing limit state of the channel as a function of relative density (i.e., the degree to which the material is foamed) is explored. The results show the key tradeoff made when foaming–stiffness per weight is increased, including stiffness related to member buckling modes; however, yield strength per weight decreases. Depending on the slenderness (in local, distortional, and global modes) of the member this tradeoff can be beneficial or detrimental.