ANALYTICAL STUDY ON SEISMIC ENERGY BALANCE OF NPP BUILDINGS PART-2 FORMULATION OF ENERGY BALANCE ON SOIL- STRUCTURE INTERACTION SYSTEM-2

摘要

This paper discusses a method for evaluating the seismic energy balance for nuclear reactor buildings of NPP which have highly strong soil-structural interaction with embedment. In order to examine the embedment effect especially from the viewpoint of energy balance, we conducted intensive nonlinear earthquake response analyses using a simple two-mass sway-rocking (SR) model with lateral soil springs and dashpots. The results clarified that the energy input through the lateral spring was negligible but the energy input through the lateral dashpot should be considered appropriately. We propose a method for converting the driving force through the lateral soil dashpot into an equivalent ground acceleration. By this method, the total input energy of the SR model with embedment can be estimated by the velocity-equivalent energy spectrum (so-called V_E spectrum) calculated from the converted equivalent ground acceleration, and the evaluation of effective input energy imposed on a building structure can be treated as the same energy distribution problem that depends on the mechanical condition between the structural stiffness and the soil springs as SR model without embedment. In addition, we conducted simulation analyses using an observed record obtained for an actual NPP building, and confirmed the validity of the proposed scheme.