APPLICATION OF THE MODAL SUPERPOSITION METHOD IN THE NON-CLASSICAL FORM FOR SOLVING THE PROBLEM OF SOIL-STRUCTURE INTERACTION OF NPP BUILDINGS UNDER THE SEISMIC EXCITATION

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Rubric:     Theoretical and experimental studies   
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The non-classical form of the modal superposition method for the solution of motion equations of soil-structure system is considered. In this case the damping matrix of system of motion equations in generalized coordinates is not diagonal. The resolving system of equations is not reduced to set of independent equations, and is solved by method of direct step-by-step integration. In comparison with the classical form of the modal superposition method, the non-classical form of this method avoids the main shortcoming – restriction of value of modal damping (it is especially important at the solution of problems of interaction of buildings and constructions of NPP with the ground base). In comparison with method of direct integration with traditional Rayleigh damping, non-classical form allows more correctly take into account the damping in constructions, and also significantly reduces the order of system of the resolving equations. Advantages of this technique are shown on solutions of model and practical problems.