Innovative seismic retrofitting strategy of added stories isolation system

摘要

The seismic performance of“added stories isolation”(ASI)systems are investigated for 12-story moment resisting frames.The newly added and isolated upper stories on the top of the existing structure are rolled to act as a large tuned mass damper(TMD)to overcome the limitation of the size of tuned mass,resulting to“12+2”and“12+4”stories building configurations.The isolation layer,as a core design strategy,is optimally designed based on optimal TMD design principle,entailing the insertion of passive flexible laminated rubber bearings to segregate two or four upper stories from a conventionally constructed lower superstructure system.Statistical performance metrics are presented for 30 earthquake records from the 3 suites of the SAC project.Time history analyses are used to compute various response performances and reduction factors across a wide range of seismic hazard intensities.Results show that ASI systems can effectively manage seismic response for multi-degree-of freedom(MDOF)systems across a broader range of ground motions without requiring burdensome extra mass.Specific results include the identification of differences in the number of added story by which the suggested isolation systems remove energy.