Techno Press
Techno Press

Structural Engineering and Mechanics   Volume 54, Number 1, April10 2015, pages 169-188
DOI: http://dx.doi.org/10.12989/sem.2015.54.1.169
 
Seismic responses of base-isolated nuclear power plant structures considering spatially varying ground motions
Mohamed A. Sayed, Sunghyuk Go, Sung Gook Choc and Dookie Kim

 
Abstract     [Full Text]
    This study presents the effects of the spatial variation of ground motions in a hard rock site on the seismic responses of a base-isolated nuclear power plant (BI-NPP). Three structural models were studied for the BI-NPP supported by different number of lead rubber bearing (LRB) base isolators with different base mat dimensions. The seismic responses of the BI-NPP were analyzed and investigated under the uniform and spatial varying excitation of El Centro ground motion. In addition, the rotational degrees of freedom (DOFs) of the base mat nodes were taken to consider the flexural behavior of the base mat on the seismic responses under both uniform and spatial varying excitation. Finally, the seismic response results for all the analysis cases of the BI-NPP were investigated in terms of the vibration periods and mode shapes, lateral displacements, and base shear forces. The analysis results indicate that: (1) considering the flexural behavior of the base mat has a negligible effect on the lateral displacements of base isolators regardless of the number of the isolators or the type of excitation used; (2) considering the spatial variation of ground motions has a substantial influence on the lateral displacements of base isolators and the NPP stick model; (3) the ground motion spatial variation effect is more prominent on lateral displacements than base shear forces, particularly with increasing numbers of base isolators and neglecting flexural behavior of the base mat.
 
Key Words
    base isolation; nuclear power plant; spatial variation; seismic analysis
 
Address
Mohamed A. Sayed, Sunghyuk Go and Dookie Kim: Department of Civil and Environmental Engineering, Kunsan National University, South Korea
Sung Gook Choc: INNOS TECH Company, Incheon, South Korea
 

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