STRESS PROFILES IN THIN-WALLED PRISMATIC COLUMNS SUBJECTED TO CRUSH LOADING .2. BENDING

This paper extends the concept of a superfolding element, developed originally for axially loaded columns to the case of bending and combined bending/compression loading. A simple kinematic model of a column was constructed with four free parameters. Closed-form solutions were derived for the moment-rotation characteristics of square columns in the post-failure range and stress profiles in the most general case of a floating neutral axis. Considerable simplifications were obtained by assuming that the neutral axis stays within the tensile flange. It was shown that, in this case, the bending characteristics of a column, can in fact, be derived from the known characteristics of an identical column subjected to axial crush. High accuracy numerical calculations were run on a square column with three different width-to-thickness ratios to check the validity of various approximating assumptions. For all three cases considered, the simplified analytical solution was shown to predict the moment-rotation relationship with an absolute error not greater than 7%. Finally, the present method was generalized of arbitrarily shaped multi-cornered sheet metal columns.