The 10 Largest Base-Isolated Buildings in the World

1. Apple Park, Cupertino, California, 445,005 square meters. Apple’s new corporate headquarters is a four-story, ring-shaped building, with a circumference of 1,512 sq ft. It houses 12,000 employees and opened in April 2017. It was designed by Foster and Partners. In addition to the four floors above ground, it also includes three stories below ground. The building sits on top of 700 base isolators. Each isolator is 7 ft in diameter and weighs about 15,000 lbs. The isolators were customized for low friction, according to the lead structural engineer, John Worley, of Arup. Construction of the entire Apple Campus 2, including the headquarters building as well as a 1,000-seat auditorium (the Steve Jobs Theater), a wellness-fitness center, two R&D buildings, a visitor center and parking structures, totaled $5 billion. The building’s inner part is a 30-acre park, featuring fruit trees, winding paths and a pond.

2. Adana Integrated Health Campus, Adana, Turkey, 430,000 square meters. The campus was developed as a public-private partnership between ADN PPP Sağlık Yatırım A.Ş., a joint venture of four firms, and the Turkish Ministry of Health. The campus will have a total capacity of 1,550 beds housed in three hospitals: the 1,300-bed main hospital, a 150-bed physical-therapy and rehabilitation hospital and a 100-bed high-security criminal psychiatric hospital. The campus is supported by 1,512 base isolators. The complex was designed by HWP, and built by Rönesans Sağlık Yatırım. The structural engineer was Ulker Engineering Ltd. It was completed in May, 2017.
Photo Courtesy Ronesans

3. Tokyo Skytree East Tower, Tokyo, 229,237 square meters. This mixed-use complex includes an office tower, mall and entertainment complex. An eight-story podium contains a shopping center, planetarium and theater serving millions of tourists visiting the observatories on the adjacent Tokyo Skytree tower. The office tower rises to 31 stories. The complex was designed by Nikken Sekkei and built by Obayashi Corp. It was completed in 2012.
Photo Courtesy Obayashi Corp.

4. Isparta City Hospital, Isparta, Turkey, 221,000 square meters. Akfen Holding, a Turkish conglomerate, built the hospital as part of a 25-year public private partnership with the Turkish Ministry of Health. Dost Insaat ve Proje Yonetimi A.S. served as the design-builder of the 755-bed facility, with architectural firm Yazgan Mimarlık & Hayalgucu Mimarlık J.V. Handling the design work. The base isolation system features 903 surface-friction-slider units supplied by Maurer AG. The project's structural engineer was Probi Insaat Proje Bilgi Islem Merkezi A.S. It was completed in December 2016.
Photo Courtesy Dost Construction

5. Logistics Park Hino, Tokyo, 212,853 square meters. A five-level warehouse with spiral ramps at both ends, it was designed by Obayashigumi Design Office and built by the Obayashi Corp. It was completed in 2015. It is owned by Mitsui Fudosan Co., Ltd.
False-3D Image by Google Earth. Imagery circa 2015.

6. Logiport Sagamihara, Sagamihara, Japan. 210,000 square meters. A five-level warehouse with spiral ramps at both ends, it was designed by Obayashigumi Design Office and built by the Obayashi Corp. It was completed in 2013. Sagamihara is a western suburb of Tokyo.
Photo Courtesy LaSalle Investment Management

7. Shinagawa Season Terrace, Tokyo, 205,786 square meters. An office building, it was designed by the NTT Facilities Design Office and built by Taisei Corp. It was completed in 2015.
Photo Courtesy Tokyoing

8. Sabiha Gökçen Airport International Terminal, Istanbul, 200,000 square meters. ISG, a partnership of Limak Holding (LIMAK), GMR Infrastructure Limited (GMR) and Malaysia Airports Holdings Berhad (MAHB) is the operator of the airport under a 20-year build-operate-transfer agreement signed in 2008. Tasked with completing the terminal in 18 months, Limak and GMR formed a joint venture and signed an EPC contract with ISG. The building's footprint is 160 m x 272 m and includes four stories above a basement level. It can serve 16 middle-sized fuselage aircraft or eight wide-body planes simultaneously. It features seven arched bays with vaulting roofs of alternating 32-m and 48-m spans, employing space frame trusses. The superstructure is a steel moment frame, resting on 292 triple-friction-pendulum isolation bearings supplied by Earthquake Protection Systems, Inc. The structural engineer who led the seismic design for the terminal was Atila Zekioglu, of Arup. The terminal opened in 2009.
Photo Courtesy openbuildings.com

9. Erzurum Regional Research and Training Hospital, Erzurum, Turkey, 180,000 square meters. It was built by Kur Construction Co. Ltd. This 400-bed hospital is supported by 386 lead-rubber bearing isolators, which were supplied by Dynamic Isolation Systems Inc.
Rendering Courtesy Prota Engineering

10. Tan Tzu Medical Center, Tai Chung, Taiwan, 157,930 square meters. Designed by C.C. Hsu & Associates, the complex includes a four- to six-story western section, a 17-story tower, and two underground levels containing parking, storage space and a cafeteria. The 1,300-bed medical center rests on 325 lead-rubber-bearing base isolators located below the second underground level. The building also is outfitted with 88 fluid viscous dampers. The lateral-force-resisting system of the superstructure consists of steel-reinforced-concrete moment frames. The total superstructure mass resting on the base-isolation system weighs 285,600 tons. The base-isolation system was designed by KPFF consulting engineers, led by Andrew W. Taylor. Construction was completed in 2006, at which time the structure was the largest base-isolated building in the world. The project was challenging, as the building is located only 400 m from the Chelungpu fault, which ruptured in the 1999 Chi-Chi earthquake.
Photo Courtesy C.C. Hsu & Associates










Base isolation is a method for moderating the effects of earthquakes on buildings. Isolator devices (either elastic or sliding) are installed between the foundation and the building superstructure. The accompanying slide show looks at the ten largest base-isolated buildings in the world, measured by total floor area.
"The use of base isolation as seismic protection for buildings, bridges and industrial facilities continues to grow, but has done so more robustly internationally than in the U.S.," says Ronald Hamburger, Senior Principal with Simpson Gumpertz & Heger, a leading seismic engineering firm.
Not surprisingly, Japan, the most seismically active country, employs it most extensively, with 4,100 base-isolated commercial and institutional buildings as of December 2015, according to the Japan Society of Seismic Isolation. "Japan looks at base isolation as a primary option," says Konrad Eriksen, President of Dynamic Isolation Systems Inc., a leading designer and manufacturer of isolators. "In the Japanese residential market, prospective condo owners will pay a premium for a base-isolated building compared to a conventional building," says Gordon Wray, associate principal at Degenkolb Engineers, another prominent seismic engineering firm.
Turkey, another very seismically active country, is also firmly committed to base-isolation methodology. Notably, it has embarked on a $13.6-billion program to build numerous large modern hospitals, most of which will be base-isolated. In addition, major bridges and viaducts have also been protected in this fashion.
One notable project under construction in Turkey is the Ikitelli Integrated Health Campus in Istanbul. The 2,330-bed main hospital building there is expected to contain 2,000 isolators. It is a public-private partnership being developed by Istanbul PPP Sağlık Yatırım A.Ş. When completed, it is expected to be the largest base-isolated building in the world.
Other countries pushing base isolation include China, New Zealand, Chile, Peru, Colombia and Ecuador. In contrast, "in the U.S., seismic isolation is used relatively infrequently," according to Hamburger. "In recent years, the inaccurate perception that other structural systems, including energy-dissipated moment frames, or buckling-restrained braced frames, can provide similar protection at lower first cost has slowed the growth of this technology in the U.S."
"In the U.S., seismic resilience is taken for granted because of the recent infrequency of earthquakes and several decades of good building codes," says Wray. "Modern buildings have performed well in recent earthquakes (few collapses), although we have not yet experienced a code-level earthquake in a densely populated area in 23 years. I believe that many building owners have an expectation of operational performance, when typical code buildings are designed only to protect life-safety."
Seismic-isolation technologies fall into two categories: elastomeric and sliding systems. Elastomeric isolation systems consist of natural rubber; natural rubber with lead cores to dissipate energy; and high-damping rubber, consisting of blends of natural and synthetic compounds. Sliding systems generally include flat sliders, typically used in combination with elastomeric bearings and friction pendulum devices. Within the friction pendulum category there are a series of different designs, including the original system that employed a single curved dish and sliding element; a double pendulum, in which two curved dish surfaces are employed; and a triple pendulum employing three such surfaces. "The triple pendulum system reduces the size of the isolator while increasing its effectiveness," says Farzad Naeim, a prominent structural engineer and former president of the Earthquake Engineering Research Institute.
Elastomeric bearings were first used on bridges in the 1950s and were found to be an improvement over mechanical bearings, which suffered from corrosion, according to Eriksen. Friction pendulum bearings were developed in the late 1980s. "Friction pendulum bearings dominate applications in the U.S., in some other important markets like Turkey, and most applications in certain types of structures worldwide (offshore oil platforms, LNG tanks, large bridges, hospitals)," says Michael Constantinou, professor of civil, structural and environmental engineering at the State University of New York at Buffalo.
"Elastomeric systems perform best in large buildings, which have large axial loads," explains Wray. "Sliding systems perform well for both large and small axial loads (large and small buildings). The behavior of sliding systems under high-frequency vertical acceleration continues to be studied."
Deformation in a building during a large earthquake is inevitable. "Using conventional lateral force resisting systems, the deformation is distributed up the height of the building among many beams, columns, connections, braces, or shear walls," comments Wray. In comparison, "using base isolation, (nearly) all of the building deformation is concentrated at the isolation plane, limiting damage up the height of the building. The magnitude of the displacement can be predicted with more certainty than the individual deformations among hundreds or thousands of individual components of a lateral system."
"Of all the seismic protection technologies presently available, seismic isolation offers the most effective protection against damage or loss of function following strong shaking," says Hamburger. "Other structural technologies allow transmission of the motion into the structure, where its energy is dissipated either through damage to the structural elements, or through more benign energy dissipation mechanisms. Regardless, structures employing these other technologies experience greater motion and as a result more damage than do isolated structures."
The evolution and spread of base isolation is influenced by many players. "Governments have played a role in funding research to develop these technologies, including Natonal Science Foundation-funded centers such as the Pacific Earthquake Engineering Research center at UC Berkeley and the Multidisciplinary Center for Earthquake Engineering Research at the State University of New York at Buffalo," says Constantinou. "Insurance agencies (and owners) have not yet taken into consideration the reduced risk of damage for a seismically isolated structure. This may change following the work of the U.S. Resiliency Council on rating building performance."
The USRC membership includes all the major professional organizations in earthquake and structural engineering, structural engineering firms, architectural firms, contractors, and hardware and software suppliers. The USRC rating system rates buildings from one to five stars for each of three criteria: safety, damage and recovery. "While many lateral systems can provide high ratings for safety, base-isolated buildings provide the greatest opportunity to achieve high ratings for damage and recovery," says Wray.
"The USRC will certify raters and review ratings after they are submitted, similar to the USGBC's LEED ratings for sustainability," says Ronald Mayes, USRC executive director and co-founder. "The rating is a different way of specifying what an owner's performance expectations are for a building. I think it will become a powerful tool." The rating system launched in December, 2015. One building has been rated so far, with 18 more in process, according to Mayes.
"The structural engineering community in the past has done a poor job of communicating what a code-designed building delivers, as attested by the performance of modern buildings in the 2011 Christchurch New Zealand earthquake, where more than 50% of the modern buildings in the central business district delivered life-safety performance but had to be demolished after the earthquake," adds Mayes.
"The Insurance industry has done little to encourage the use of seismic isolation, and it could be said that offering an earthquake mitigation alternative to developing earthquake-resistant structures, actually provides a disincentive," says Hamburger. "The primary insurance benefit the owner of a seismically isolated structure obtains is through an ability to purchase greatly reduced levels of protection. Some owners have chosen to use base isolation as their earthquake insurance of choice, as any damage that may occur is well below current deductibles. In addition, base isolation provides business continuity, something that is very difficult to cover with insurance."
The order of the slideshow accompanying this article was updated on July 27, 2017 to reflect new information.