This study is to make a seismic design database of mid-story isolated buildings based on performance evaluation sheet of 60 buildings. From information provided by this database, following tendencies are confirmed; 1) The mean value of the 1st natural period is about 0.5 seconds longer than that of base isolation buildings. 2) The maximum deformation of the isolation story is about 6cm larger and maximum responses of the upper-structure are larger. 3) The tendency of the mass damper effect and modal coupling effect are confirmed as compared responses of the design cases and the response prediction method.
