Design of fixed-ended octagonal shaped steel hollow sections in compression

Abstract

In recent years, octagonal steel hollow sections (OctHSs) have attracted significant interests from researchers and engineers, and OctHSs have been employed in civil engineering applications. However, designs of OctHSs are not included in structural steel design codes. This paper therefore presents comprehensive numerical analyses on the stub column behaviour of OctHSs. A database of 46 stub column tests reported in 6 sources were collected. Different fabrication routes, steel grades and cross-sectional slenderness were covered. Finite element (FE) modelling was carried out to replicate the test observations. The validated FE models were subsequently adopted to conduct an extensive parametric study to supplement the test database. Existing design methods in North American specifications, ASCE standard, Eurocode, Australian code and recently published literature were thoroughly discussed and evaluated. It was found that existing design methods are not applicable to the design of OctHSs. New cross-sectional slenderness limits and modifications to the existing design methods were then proposed. The cross-sectional resistance obtained from different design methods were compared with test and FE results. The applicability of the modified design methods was confirmed by statistical analyses. The reliability of the modified design methods was finally verified through reliability analyses. Results indicate that the modified design methods can be used to accurately predict the resistance of OctHSs with accepted safety levels.