Seismic Performance of Story-Added Type Buildings Remodeled with Story Seismic Isolation Systems

Story-added type apartments have recently been introduced as an option to resolve the housing supply shortage in areas that are undergoing rapid industrialization and urbanization. However, the infrastructure of old apartment buildings (>20 years old) makes it difficult to introduce convenient facilities and recent technologies such as those involving the Internet of Things and augmented realities. Applying housing technologies to existing older apartments can increase housing supply and potentially address the aforementioned issues. However, story-added building remodeling increases the weight of existing buildings, necessitating seismic reinforcement, which is the major obstacle when performing vertical building extensions. This study presents methods for lowering seismic loads associated with vertical augmentation of buildings while improving the seismic performance. A model of a vertically extended building with three additional stories constructed on top of an existing 15-story apartment building was used. The applied seismic isolation system decreased the maximum response acceleration on top of the remodeled building by approximately 70% and 65% in the X-direction and Y-direction, respectively, while decreasing the base shear plane by approximately 30% in both the X- and Y-directions in comparison with forces on a non-seismically isolated building. These results demonstrate that the use of a seismic isolation system can significantly reduce seismic loads.