- Rectangular finite elements based on a Reissner type variational statement for plate bending are applied to stability and free vibration of rectangular plates. The finite elements are constructed from the weak statements of the two normal moments-displacement relations and the moment equilibrium equation in terms of the two normal moments. These finite elements are algebraically simple and yield better accuracies for the critical loads and natural frequencies when compared to conventional finite elements. Linear and quadratic rectangular finite elements are used to calculate frequencies and buckling loads of rectangular plates with various edge conditions. 1977.