Trend of Building Structure Design in Japan
- Toshihiko Iijima
- IIJIMA Structural Design Office Co., Ltd.
In Japan, since the Great Hanshin-Awaji Earthquake in 1995, many major earthquakes have been occurring and causing great damages. Considering these damages by the earthquakes, four issues need to be newly addressed in addition to the normal seismic design.
- (1) Tsunami
- (2) Long period ground motion
- (3) Maintaining building functions and continued use
- (4) Secondary structure such as ceiling
- (1) Before 3.11, main focus in structural design was earthquake-resistant design, and tsunami did not get a great attention. Therefore, massive damages caused by 2011 Tsunami in the Great East Japan Earthquake gave a great shock and lesson to structural designers.
- (2) Long period earthquake drew attention for the first time in the Tokachi-oki-Earthquake-2003. Long period ground motion is transmitted to the far distance because of little attenuation ratio. This is why intense shakes hit the skyscrapers and building with dampers in areas far from the epicenter.
- (3) When government agencies or hospitals which are critical buildings in time of earthquake are heavily damaged, it becomes difficult for the buildings to maintain their function. It is important that building functions are maintained and can be used even after the earthquake. So, damages from the earthquake should be minimized.
- (4) People tend to focus on damages in the main structure, but there are secondary damages such as fallen ceiling or damage on secondary structures. Fallen ceiling in the gym and hall due to earthquake is a serious problem because it can be fatal to humans.
Dr. Toshihiko Iijima, founder and president of Iijima Structural Design Office, obtained a diploma in architecture from the Engineering Faculty of Kanto Gakuin University in 1945. He pursued graduate’s study in Nagoya University to obtain a master’s degree in 1947 and doctor’s degree in 1953. In 1950, he founded a structural design office which is in operation to date. Being a specialist of structural design for aluminium buildings as one of his expertise, Dr. Iijima joins in creating design standards for aluminium building structures. He wrote and co-wrote three books on aluminium structures, and was awarded a Matsui Gengo special award by Japan Structural Designers Club for his contribution in spreading aluminium buildings. He also worked as a part-time professor in Nagoya University, Meijo University and Kanto Gakuin University. Iijima Structural Design Office is specialized in various structural design including RC, steel frame, wooden and aluminium structures as well as dynamic design for buildings with seismic isolation/dampers and skyscrapers.