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 Vol. 32 Spring 2005 |
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The Kobe Earthquake:Applying Lessons Learned,10 Years after the Disaster This year is the 10th anniversary of the Great Hanshin-Awaji Earthquake, which struck Kobe and the surrounding area on January 17, 1995. The powerful inland earthquake had a magnitude of 7.3 on the Richter scale, took 6,433 lives, and totally or partially destroyed more than 250,000 buildings. In October 2004, the Niigata Chuetsu Earthquake, which measured 6.8 on the Richter scale, claimed 40 lives, damaged or destroyed 100,000 buildings, and forced 100,000 local residents to live in temporary evacuation shelters. Then, on December 26, a massive quake off the coast of Sumatra, Indonesia unleashed giant tsunamis that caused unprecedented death and destruction along thousands of kilometers of shoreline in the Indian Ocean basin. These recent disasters were a terrifying reminder of the importance of disaster preparation. In this feature article, we introduce what we have learned following the series of major earthquakes and what kind of technologies have been developed over the past 10 years to prevent damage. The Violent Force of the Great Hanshin-Awaji Earthquake One of the harsh lessons learned from this earthquake was that nearly 90% of the victims died from being crushed or asphyxiated due to the collapse of structurally fragile old buildings. Enormous damage and injury occurred even when buildings did not collapse, owing to the disruption of lifelines and the falling down of interior fixtures or equipment such as computers. The earthquake resulted in the loss of internal functions at hospitals engaged in emergency treatment and at schools and other public facilities that serve as evacuation areas, seriously hindering disaster-relief efforts. Although finding a way to prevent the collapse of buildings is the highest-priority task to contain damage from future quakes, at the same time it is essential to devise systems to keep buildings from swaying. Buildings That Do Not Collapse, and Systems to Prevent Swaying Japan is among the countries with the most frequent occurrence of earthquakes in the world. If small quakes with a magnitude of about 1 on the Richter scale were included, more than 1,000 earthquakes occur in Japan each year. That is why Japan is a world leader in earthquake engineering technical research, and in this regard Kajima's Technical Research Institute plays a key role. Kajima has developed and commercialized a wide array of earthquake protection construction methods to meet seismic reinforcement requirements for new buildings and existing structures. We also developed a series of technologies to prevent building sway during a quake to minimize damage. These construction methods include a vibration damping system that uses oil dampers to control the slight vibrations caused by wind-induced swaying to severe shaking from major earthquakes, a seismic isolation system utilizing multi rubber-bearing and other devices, and earthquake-proofing and seismic isolation reinforcement methods to retrofit structures even as the occupants continue to work or live in them. Kajima has deployed these construction methods at more than 160 buildings in the past 10 years. They offer proven high cost-effectiveness, and their use is expected to increase in the coming years. |
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A Hospital Incorporating Lessons Learned from the Earthquake One of the latest examples in adopting the latest design concept and technology is the Kobe Red Cross Hospital opened in August 2003 in HAT Kobe, the new city center in eastern Kobe. Along with the jointly established Hyogo Emergency Medical Center, the hospital is expected by many to become a core facility for community healthcare, as well as emergency and disaster medicine. The hospital-medical center complex is the outcome of the fusion of plans conceived by the Red Cross and Hyogo Prefecture in the aftermath of the Great Hanshin-Awaji Earthquake. The Red Cross considered it an urgent priority to establish a hospital to offer sophisticated routine medical care suited to the needs of the times, while serving as a facility capable of providing adequate emergency medical care on a prefectural scale in an emergency. For its part, Hyogo Prefecture envisioned a center to perform the critical disaster-response functions of supplying medical care, gathering information and issuing directives, transporting patients, and stockpiling medication during large-scale disasters. |
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The Kobe Red Cross Hospital and Hyogo Emergency Medical Center Complex Design and supervision: Hyogo Prefecture, Yamashita Sekkei Inc. Construction: Kajima Kansai Branch |
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The new Red Cross facility is a general hospital with 19 medical departments, a pathological examination department, and 310 beds (the Emergency Medical Center has 30 beds). The hospital building has a seismic isolation structure that can withstand an earthquake with a magnitude of 7.0 on the Richter scale. The seismic isolation mechanism, which involves attaching 112 high-damping rubber-bearing seismic isolation devices between the base of the superstructure columns and the foundation to suppress transmission of ground motion to the building, reduces horizontal shaking to one-third to one-fifth during a quake. The hospital's corridors and laboratories are equipped with medical gas supply systems and other medical infrastructure, so that the number of beds can be increased to up to 600 in an emergency. |
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Kajima's Vibration Control/Seismic Isolation Technology Are Confirmed in an Earthquake The Niigata Chuetsu Earthquake struck on October 23, 2004 on the Sea of Japan side of the island of Honshu. Immediately afterward, Kajima established an earthquake countermeasures headquarters on the scene and offered full cooperation and support for the restoration of railways, roads, and buildings. As the extent of the damage became known, the general administration building of Hokuriku Gakuen, located in the city of Nagaoka, Niigata Prefecture near the quake's epicenter, became a focus of attention. Kajima completed the building's construction in 1997, employing a seismic isolation construction method that demonstrated superb seismic isolation performance during a quake in the area that registered a magnitude of 6.0. Not only the building itself, but also the internal fixtures and fittings came through the quake unscathed; it is said that even flower vases on shelves inside the building did not topple over. Meanwhile, in the city of Niigata, situated 70 kilometers (43 miles) from the epicenter, a building erected by Kajima in 2003 demonstrated robust earthquake resistance to match its design specifications. Standing 140.5 meters (460 feet) high, the 31-story Niigata Bandaijima Building is the highest building in the region adjoining the Sea of Japan. It is equipped with Kajima-developed oil damper vibration control devices (HiDAX + HiDAM). Although an intensity of 4.0 was recorded in Niigata City, guests at the Hotel Nikko Niigata reported feeling nearly no shaking. Kajima will analyze vibration data gathered from the two buildings with the aim of developing seismic isolation and vibration control technologies that offer even greater accuracy. The durability of these buildings in a catastrophic earthquake has attracted the attention of municipal government offices, schools, hospitals, and other facilities that serve as disaster-prevention facilities, and Kajima considers it important to rapidly disseminate information on the buildings' performance. |
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Providing Means Preventing Many examples of escaping collapse or damage by implementing appropriate earthquake protection measures or structural reinforcement were found at the time of the Great Hanshin-Awaji Earthquake and the Los Angeles Earthquake of 1994 (with a magnitude of 6.7). The words of a high-ranking Los Angeles municipal official at the time of the quake there are telling: "We should not spare cost in preparing for future disasters. In view of the loss of life and the blow to the local economy, at the end of the day this isn't economy in expenditures." The same can be said of households and smaller communities. People who live on the earthquake-prone archipelago of Japan must be prepared for the worst. Consequently, Kajima is continuing its quest to provide safety and security by developing ever more effective earthquake protection technology. |
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 Vol. 32 Spring 2005
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