CLASSIFICATIO N OF NONLI NEAR SOLUTIO NS OF THE STA BILIT Y PRO BLEM OF STIFFE NED PLATES TA KING INTO ACCOU NT THE INTERACTIO N OF TWO FORMS OF STA BILIT Y LOSS AND THE INFLUE NCE OF INITIAL IMPERFECTIO NS (PART ONE).

In this paper we consider the stability problem of a thin reinforced plate taking into account the interaction of shapes and the influence of initial geometrical imperfections, present a complete classification of nonlinear solutions of the stability problem, show the relationship between the appearance of singular points and the rank of the extended Hesse matrix, and obtain the values of bifurcation loads in the linear formulation of the problem.