A first known investigation into the vibratory characteristics of rect
angular Mindlin plates with intermediate stiffeners is presented. The
Rayleigh-Ritz method is used, with displacement and rotational functio
ns assumed in the form of mathematically complete algebraic polynomial
s. Sets of numerical frequency parameters for rectangular plates of va
rious boundary conditions, thicknesses and plate dimensions are presen
ted. In the study, the effects of shear deformation and rotary inertia
on the vibrational response of the plate structures are investigated.
The influence of torsional rigidity and geometric properties of stiff
eners on the natural frequency parameters are included. To validate th
e proposed formulation, numerical results for some simplified problems
have been determined where existing literature for these problems can
be found. Finally sets of new vibration frequencies for plates with o
ne or more stiffeners in various directions are presented.