Like Japan’s Millennium tower, tall buildings in Chicago—Illinois and San Francisco—California, USA namely John Hancock Centre and Transamerica Pyramid are built in an active earthquake region, thus it is vital that tall buildings are designed and built according to a stringent code to withstand strong tremors (Fig. 9.11). The Transamerica Pyramid, a 48 storey high office building (260 m high),
Fig. 9.11 Transamerica Pyramid skyscrapers in USA and Japan. (a) John Hancock Center, Chicago (b) Transamerica Pyramid, San Francisco (c) Millennium Tower, Tokyo. Source links: https://postcardemily.files.wordpress.com/2011/10/hancock-tower_front.jpg; http://i1.trekearth. com/photos/40227/sfa.jpg; http://www.fosterandpartners.com/media/Projects/0504/img1.jpg
was built in 1972. This unique pyramid shape gives the structure more stability than a typical skyscraper. Also, it is built on a steel and concrete foundation (16 m) deep in the ground and able to swing with tremors. During the 1989 Loma Prieta earthquake, the tall building shook for more than a minute and the top storey swayed nearly 0.3 m, but the Transamerica Pyramid was undamaged (Murdico 2006). Even under the 7.1 magnitude 1989 Loma Prieta earthquake in central California San Francisco’s Transamerica Pyramid suffered no significant damage. This is attributed to the pyramid’s shape and “earthquake-friendly” foundation, hence an added value to sustainability.