The behavior of the sandwich reinforced plate-beam on the elastic basis under the influence of harmonious force enclosed on some distance from supported edges, and also dynamic loading, linearly time-dependent, is investigated on the basis of nonlinear deformation model. It is shown, that at definition of the basic vibration frequency the solution can be received from the static formula, having replaced the valid factor of "bed" in the reduced size connected with forced vibration frequency. At the load application of a power impulse to a sandwich beam its buckling process is considered, when the amplitude of the maximum deflection sharply increases with time growth that will be coordinated with a problem of dynamic behavior of the three-layer composite shell received earlier by authors.

Key words: fluctuations frequency, reinforcement, elasticity, deformation, dynamic loading, rational designing.