Simplified Direct Strength Method for the design of cold-formed steel channels with circular web openings under two-flange loadings
Wei Wang, Krishanu Roy, Beulah Gnana Ananthi. G, L. W. Lu, Zhiyuan Fang, James B.P. Lim
Abstract
Previous studies have put forward reduction factor equations to determine the web crippling strength of cold-formed steel (CFS) channels with circular web openings. However, these equations overlook vital parameters such as material yield strength, flange width, and fillet radius of CFS channels. Consequently, this paper introduces simplified Direct Strength Method (DSM) equations, which account for plastic loads ( P y ) and elastic buckling loads ( P cr ), integrating the aforementioned crucial parameters. Eight unique yield line models were devised, considering two-flange loadings: interior-two-flange (ITF) and end-two-flange (ETF), as well as the positioning of circular web openings, to compute the yield line length for P y . Similarly, new P cr equations were also proposed. The reliability of the proposed equations was evaluated using a dataset of 236 test results sourced from the literature. This assessment aims to demonstrate the suitability of the equations for incorporation into future revisions of international design codes. • This paper introduces simplified Direct Strength Method (DSM) equations for determining the web crippling strength of CFS channels with circular web openings under two-flange loadings. • Eight novel yield line models, accounting for various load cases and positions of circular web openings, were developed to compute the yield line lengths. • New critical loads ( P cr ) equations, considering the effect of circular web openings, were obtained through regression analysis.