Seismic Response Analysis Of Story Isolation Structure On Soft Ground

Story isolation technology is developed from base isolation,and it is not widely applied in practical engineering yet,what's more,the codes regulate the height and site of the isolated structures,and the current literature about the story isolation structures are seldom about shear wall structures.This paper made some breakthroughs,so as to promote story isolation technology.A story isolation structure built on subway platform in Tianjin(class III site)was given as an example.Through the dynamic time history analysis in ETABS software that considered the nonlinearity of the bearings,it was concluded that the isolatied upper structure would suffer less seimic hazard,under the medium earthquake,the seismic reduction efficient was 0.45.Both earthquake intensity and earthquake resistant measures can be reduced by half degree when designing the upper structure,while the horizontal seismic reduction of lower structure was not obvious.The elasto-plastic dynamic time history analysis under the large earthquakes through the EPDA of PKPM software was carried out.Under the large earthqueke,the tensile stress and bearing deformation didn't exceed the limit value of the code.It's concluded that under large earthquake,the isolated upper structure shifts in plane,seldom cracks happen in the isolated structure,while the unisolated structure appears bending failure and cracks happen on almost the whole structure.Through the analyses of the same story-isolation struction built on different sites,it showed that the isolation effect of site ? is good,the seismic reduction coefficient was small and the bearing deformation didn't exceed the limit.While,when built on site ?,the isolated structure suffered larger story force,the bearing deformation and structure displacement exceeded the code.Therefore,it is possible for the high-rise isolation structure on site ? to achieve the expected target of reducing half degree when designing the upper structure,which can greatly improve the safety and durability.But site ? leads to poor effect of seismic reduction,and more attention should be paid on designing and analyzing the seismic reduction structure built on it.