The shift of the effective centroid in plain channel section columns

Abstract

The report derives an equation for the shift of the effective centroid that occurs in plain channel section columns as a result of local buckling. The shift causes bending when the column is compressed between pinned ends and may need to be accounted for in design. The equation is based on Stowell’s work on simply supported plate elements with a free longitudinal edge. It is shown to be in reasonable agreement with eccentricities calculated using results of geometric nonlinear shell finite element analyses of plain channel columns. It is also shown to provide more accurate values of eccentricity than the effective width method, in which the effective width of each plate element is calculated to produce an effective cross-section and an associated effective centroid.