Web crippling behaviour of cold-formed unlipped channels

Abstract

An experimental investigation of cold-formed unlipped channels subject to web crippling is described. The tests were carried out under four loading conditions according to the AISI Specification, namely End-One-Flange (EOF), Interior-One-Flange (IOF), End-Two-Flange (ETF), and Interior-Two-Flange (ITF) loading. The concentrated load or reaction forces were applied by means of bearing plates which acted across the full flange widths of the channels. The web crippling test results are compared with the American Iron and Steel Institute (AISI 1996) Specification and the Australian/New Zealand Standard (AS/NZS 4600-1996) for cold-formed steel structures. The design web crippling strength predictions given by the specifications have been found to be very unconservative for the unlipped channel sections tested. In this paper, simple plastic mechanism formulae for web crippling strength of unlipped channels are proposed.