Nonlinear seismic soil-structure interaction analysis of nuclear reactor building considering the effect of earthquake frequency content

A three-dimensional nonlinear soil-structure interaction analysis is simulated in time domain in order to evaluate the behavior of a nuclear reactor building under different earthquake motions. The effects of earthquake frequency content and soil-structure interaction are taken into account by using three different ground motions and four different soil types. Viscous boundary and free-field column are used to absorb propagating waves and consider the free-field motion in the soil medium, respectively. Analysis of three cases are carried out: (i) linear analysis, (ii) nonlinear analysis with the bonded contact between superstructure and soil medium, and (iii) nonlinear analysis with the sliding contact between superstructure and soil medium. The results obtained from the time domain are validated by using a code in the frequency domain, and a good agreement is found between two methods. By changing the soil properties and ground motions, some comparisons of the nuclear reactor responses are made. It is concluded that both of soil-structure interaction and earthquake frequency content are highly sensitive to the behavior of nuclear reactor building under seismic loading. Also, this research leads to some new findings that are useful for practical applications while considering the soil-structure interaction and earthquake frequency content in nuclear structures.