Deformations of Geometrically Imperfect Beams

The effects of a number of representative types of imperfection on the elastic deformations of simply supported I-beams with either equal end moments or central concentrated load are investigated, and it is shown that each of these imperfections can be approximated by an equivalent sinusoidal initial crookedness or twist. The results of this investigation are then used in an examination of a linear plot method of extrapolating for the elastic critical load devised by Massey, and it is concluded that the plots obtained by this method may be nonlinear. An improved method of extrapolation is suggested and the critical load estimates made by this method from a number of experimental measurements are compared with the Massey plot estimates and the theoretical predictions.