Prediction of ultimate capacity of perforated lipped channels

Local buckling behavior of symmetrically perforated lipped channels is inve stigated experimentally and analytically, A total of 63 stub column tests h ave been carried out to investigate the effects of the size, position, and aspect ratio of rectangular holes on the ultimate compressive strength of p erforated columns. A formulation is proposed to predict the ultimate load-c arrying capacity of such channels. In the proposed approach the web plate w ith two rectangular holes is idealized as two unstiffened elements and a ce ntral column. The effective width of an unstiffened element is estimated by the Cold-Formed Steel Design Manual, published by the American Iron and St eel Institute in 1996. The Perry-Robertson approach is modified to predict the strength of the central column. The proposed formulation is shown to pr edict the ultimate strength of perforated columns accurately. The size and positions of holes are the most influential factors determining the weakeni ng effect. The aspect ratio of the rectangular holes has only marginal effe cts for lipped columns.