The prediction of the crushing strength and corresponding energy dissipation of unstiffened and stiffened plates under axial compression is discussed. Semi-empirical formulae for the crushing strength and dissipation energy of these stiffened plates are derived from the assesment of the structural behavior of unstiffened and stiffened box columns consisted of rectangular plates with longitudinal, transverse and orthogonal stiffeners. To demonstrate the effectiveness of proposed formulae, they are compared with the existing formulae and experimental results, which are shown in good agreements.