Effect of Web Perforation on the Behaviour of Cold-formed Steel C-shape Slender Column Subjected to Non-uniform Cross-sectional Distribution of Elevated Temperature

摘要

Presented in this paper is a numerical investigation on the effect of web perforations on the behaviour of cold-formed steel C-shape columns subjected to non-uniform cross-sectional distribution of elevated temperature with use of finite element analysis. The length of web perforation investigated varies from 0 mm to 630 mm (25 in.). The non-uniform cross-sectional distributions of elevated temperatures are obtained from finite element thermal analysis of insulated CFS walls subjected to standard fire up to 105 minutes. Sequentially coupled thermal-stress analyses were carried out under a transient state condition. The concentrically loaded cold-formed steel C-shape columns with load ratios of 0.6, 0.7, 0.8 and 0.9 are investigated. Initial global geometrical imperfection is accounted for in the. It is found that the column failed by global buckling about its weak axis together with the local failure around the region of the web perforation at mid-height of the column and thermal bowing towards the fire-exposed side. The obtained results from the finite element analysis demonstrate that the web perforation has an influence on the temperature distribution of the cross-section of the C-shape column, but the temperature gradient within a cross-section is hardly associated with length of the web perforation. As a result, the differences of failure times among the cold-formed steel C-shape columns with different lengths of web perforation subjected to a same load ratio are found to be within 10%.