Experimental investigation of cold-formed channels subjected to combined bending and web crippling

Abstract

An experimental investigation of cold-formed channels subjected to combined bending and web crippling is described in this paper. A series of tests was performed on unlipped channels rolled from high strength structural steel sheets having nominal plate thickness up to 6 mm, and a maximum web slenderness value of 45. This value is considerably lower than the intended web slendemess values used in the Australian/New Zealand Standard (AS/NZS 4600, 1996) and the American Iron and Steel Institute (AISI, 1996) Specification for cold-formed steel structures. In the past, the typical thickness of cold-formed steel members was less than 3 mm, and this was due to the limitations of the cold-forming technology in the 1980s. The design rules in the AS/NZS 4600 and the AISI Specification for members subjected to combined bending and web crippling are mainly based on test results having plate thickness less than 3 mm with web slendemess values greater than 45. Therefore, the appropriateness of the design rules for members having plate thickness greater than 3 mm is investigated in this paper. The specimens were tested at various lengths using the Interior-One-Flange (IOF) loading condition specified in the AS/NZS 4600 and the AISI Specification. The test strengths are compared with the design strengths obtained using the AS/NZS 4600 and the AISI Specification. Generally, it is shown that the specifications conservatively predicted the strengths of the tested unlipped channels subjected to combined bending and web crippling.