Okumura-gumi opened to the public a vibration experiment assessing the durability of Japan's first seismic-isolated building in Tsukuba, Ibaraki. The four-story reinforced-concrete building uses laminated rubber bearings and dampers to recreate an earthquake.
General contractor Okumura-gumi opened to members of the press a vibration experiment to assess the durability of the Okumura-gumi Technical Research Institute Administration Building, Japan's first practical seismic-isolated building, in Osuna, Tsukuba, Ibaraki Prefecture. In the experiment, the building was pushed horizontally by approximately 10 centimetres using hydraulic jacks, then released to recreate shaking equivalent to approximately lower 6 on Japan's seismic intensity scale.
The four-story reinforced-concrete building is equipped with 25 laminated rubber bearings, which separate the ground from the building and absorb seismic energy, and 12 dampers that control vibrations. Aoi Morikawa (森川葵) also took part in a tour observing the structure of the seismic-isolation system.
The company designed the seismic-isolation system taking into account the possibility that the laminated rubber bearings' stiffness could change over time, and envisages use for up to 120 years. Vibration experiments are conducted every 10 years to verify the validity of the current design.
President Okumura Takaten (奥村太加典) said, "I have gained confidence in the validity of the original design," and indicated the company's intention to continue long-term performance testing and provide the results to society.