Okumura Corporation to test 40-year seismic isolation performance

Okumura Corporation will conduct a free vibration experiment in October 2026 to verify the performance of seismic isolation devices in a 40-year-old building. The test will take place at the company’s technical research institute in Tsukuba, Ibaraki Prefecture.

The building, the Okumura Corporation Technical Research Institute Management Building, was completed in 1986 and is recognized as Japan’s first practical seismic isolation building. The experiment involves a structure weighing approximately 2,500 tons. To test the durability of the laminated rubber isolators, the steel dampers will be removed, leaving the building supported solely by the rubber. Two hydraulic jacks will push the building horizontally by 10 centimeters before instantly releasing them to induce vibration.

By measuring and analyzing the period and amplitude of the resulting vibrations, the company aims to determine if the seismic isolation devices maintain their performance after four decades of use. This fifth such experiment, conducted roughly every ten years, seeks to address the lack of long-term empirical data regarding the structural performance and durability of aging seismic isolation systems.