Buckling of Web Plates under Combined Loadings

A modified Rayleigh Ritz energy method is presented for the calculation of the critical load of a plate under complex loadings. The method is then used for the calculation of the critical load of a plate under partial edge loading, and also under bending and shear stresses. Calculations for the interaction curves have been carried out for aspect ratios from 1/3 to 2 and for partial edge ratios of 1/4 to 1 with respect to the shorter side. The plates are assumed to be simply supported on all sides. The results are presented in the form of interaction curves which show that the presence of the partial edge load reduces the interaction curve for the bending and shear stresses. The critical coefficients under positive bending or shear stress decrease in the presence of a partial edge load. However, for negative bending stress there is very little interaction with the partial edge load. It is also indicated how these curves can be utilized for the calculation of the critical strength of the web of a plate girder.