Technologies and Solutions - Architectural Technologies

Base Isolation Installation Without Leaving: “Retrofit”

By adding new seismic isolation function to the existing foundation, this method can reinforce the earthquake resistance without adding seismic members to the upper structure while occupants are staying.


  • It is a construction method that can seismically isolate existing buildings supported by piles. This method is suitable for buildings of historical value because it doesn’t change the appearance of the building. It is also appropriate for buildings of which uses are difficult to be suspended such as public facilities and hospitals because the building can be retrofitted while in use.
  • The clearance that can be excavated around the building (approximately 2 to 4 m depending on the condition) is necessary.
  • It can be applied to buildings with a tower ratio of less than 3 (tower ratio = building height / building width) where no pulling force is generated in the seismic isolation device.
  • We acquired the patent (Patent No. 2819008) as Toyo type retrofit (TOTRO) that retrofit of an existing building can be further made in a labor-saving way.

Construction examples

  • ● Seismic repair of Central Government Building no.3