Rotational Stiffness Requirements of Closed-Section Stiffeners for Buckling Strength Increment of Stiffened Plates Under Uniaxial Compression

In these days, closed form solutions to estimate the strength increment in the local buckling strength due to the rotational stiffness of the closed-section ribs have been proposed through theoretical approaches using the energy methods and parametric numerical analysis. In this paper, the correlations between the local buckling strength of longitudinally stiffened plates and the rotational restraint stiffness of closed-sections ribs were thoroughly investigated through numerical analyses. Three-dimensional finite element models of longitudinally stiffened plates were obtained using ABAQUS, and a series of comprehensive parametric numerical analyses were conducted in order to reveal the influential design parameters for required rotational stiffness of closed-section ribs for reaching converged buckling strengths. Then, a simplified design equation for the required rotational stiffness for the stiffened plate buckling strength has been proposed, which are applicable for both flat and curved plates to achieve optimum design sections. The comparative study and trend analysis showed that the proposed design methods have a good correlation with the numerical analysis results. Finally, a series of design examples demonstrate a design process of the longitudinally stiffened plates with closed-section ribs by using the proposed design equations.