Abstract
Various seiemic retrofit methods for exisiting foundations of structures are suggested in order to adapt to Level-2 earthquake wave after Hanshin-Awaji Earthquake Disease in 1995. However, most of seismic retrofit methods for foundation structures which have been suggested ever takes high cost to need underpinning method for existed structures and to excavate soil around existing foundation.
This paper shows that ground surface slab concrete on backfill soil makes it possible to reduce horizontal force to existing foundation structures in earthquake and to reduce cost for seismic retrofit construction not to need excavating with centrifugal model test.
Furthermore, it is confirmed that the ground surface slab concrete fixed by piles can reduce less horizontal force to foundations than that in case of the only ground surface slab concrete.
