Reuse of Underground Substation

The existing underground substation remains in use, while the superstructure is demolished and replaced with a new building.

Reuse of existing underground infrastructure while reconstructing the superstructure

The underground substation, an integral piece of social infrastructure, will remain as is, and only the above-ground structure will be demolished and rebuilt. The substation cannot be relocated due to the complexity of shutting it down and reconstructing the cable caverns beneath Tokyo’s roads. Therefore, to ensure business continuity and effectively utilize this social capital, we will renovate the aging superstructure and convert it into a housing complex, while leaving the underground facilities untouched.

Measure to safeguard the existing underground structure during seismic activity

To minimize the impact on the existing underground structure, we use a base-isolation structure that reduces seismic forces.
The upper portion of the building is seismically isolated through a steel frame structure, which also reduces the building’s weight. The seismic isolation functions by contrasting the rigidity of the upper base isolation section with that of the lower base isolation section, which is a reinforced concrete structure with earthquake-resistant wall structure. Additionally, the existing basement frame is surrounded by 630 mm thick ICOS walls, which provide effective horizontal resistance for the foundation.