RESPONSE OF BASE-ISOLATED NUCLEAR STRUCTURES TO EARTHQUAKES
Abstract
A method for evaluation of the dynamic response of base-isolated nuclear power plants and the performance of aseismic rubber bearings in the vertical direction is presented in this dissertation. The method is based on the Finite Element analysis technique in which the structure is subjected to the ground motion filtered through the base isolation system. The isolation system consists of two concrete rafts separated by concrete pedestals and aseismic rubber bearings. The concrete pedestals are positioned on the lower raft, which rests on the ground, and are located on top of the concrete pedestals and are modeled by viscoelastic elements. The vertical ground motions of four major earthquakes (Taft 1952, El Centro 1934, El Centro 1940 and Olympia 1949) are used as input excitations in this study. Furthermore, it is assumed that the motion of the lower raft is represented by the ground motion during an earthquake, and there is no interaction between the soil and the lower raft. Equations of motion for the modeled structure are derived in matrix form and a step by step numerical integration scheme is used to solve these equations. It is found that a well designed isolation system with adequate damping has a good performance, and can be used for isolation purposes against earthquakes satisfactorily. All computations and plots in this study are carried out using the computer program SAP IV and other computer programs developed in Fortran IV on the Purdue University CDC 6600 computer system.
Degree
Ph.D.
Subject Area
Civil engineering|Energy
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