Application of base isolation systems has attracted much attention in recent years. It ismainly because, the effectiveness of seismic isolation systems has been verified against therecent strong earthquakes in Japan, United States and some other countries. One of the casesthat may need more investigation is to clarify the effects of soft soil properties on theresponse amplification of base-isolated structures, since the resonance between isolatedsuper-structure and soft-soil frequencies during strong motion excitation may cause seriousproblems. In this study, several numbers of the relevant theoretical and numerical models forpile and soil combination are reviewed and compared. A numerical model consisting oflayered soil profile, pile-foundation, base isolator and a super-structure building is developedon the basis of a nonlinear soil-pile-structure model. As a case study, numerical simulation isverified by using the existing database of a 10-story building designed in Japan. The resultsindicates that the closer the periods, the larger the peak displacement of isolator is, however,it has less influence on the peak acceleration transmitted to the super-structure. It is clearfrom this study that for any site-specific earthquake, an appropriate isolation system canprovide sufficient margin of protection for the isolated structure depending on how theeffective period of the isolated part is far from dominant period of the site.
展开▼
