12/6/2012 Application of Seismic Isolation-U.S. Application of Seismic Isolation-U.S. 1200 mm LF Application of Seismic Isolation-Japan Application of Seismic Isolation-China Performance in Earthquakes Performance in Earthquakes 7 12/6/2012 7 Course Seminar, Tongji University, December 12, 2012 Application of Seismic Isolation – U.S. • ~300 isolated buildings • Specialized applications, limited to essential buildings and historic retrofits in high seismic zones • Designed for higher performance standards • 5-10% increased construction cost impediment to ordinary structures SF City Hall Stanford hospital Course Seminar, Tongji University, December 12, 2012 Application of Seismic Isolation – U.S. Berry Street Project in San Francisco • 2-story isolated vertical addition to existing 3-story building • Objective: maximize additional space but minimize disruption • 1200 mm LRB and 600 mm elastomeric sliders to accommodate large displacements under light vertical loads Course Seminar, Tongji University, December 12, 2012 Application of Seismic Isolation - Japan • ~5000 isolated buildings in Japan • Applications spurred by 1995 Kobe EQ • Earthquake awareness based on historical seismicity • Commercial and residential use • High rises (50 stories), small homes • Public demand and market for seismic protection Application of seismic isolation in Japan (clark et al. 2000) Course Seminar, Tongji University, December 12, 2012 Application of Seismic Isolation – China • ~600 isolated buildings • Applications slowly started in 1993 and increase in 1997 • Introduced into code in 2001, recently revised in 2010 • Potential for significant increase in use following 2008 Wenchuan Earthquake • Highest isolated structure is 20 stories SOURCE: Pan et al. 2012 Seismic Isolation of building group in Beijing Course Seminar, Tongji University, December 12, 2012 Performance in Earthquakes • USC University Hospital in Los Angeles during 1994 Northridge EQ • 8-story steel superstructure supported by 149 elasotimeric isolators • Reduced accelerations by 66% at the base and 40% at the roof. (USGS, http://pubs.usgs.gov/fs/2003/fs068-03/fs068-03.pdf) Course Seminar, Tongji University, December 12, 2012 Performance in Earthquakes • Building in Ojiya during the 2004 Niigata, Japan EQ • Lateral acceleration is reduced by 25% • Vertical acceleration increased by 150% (how to isolate vertically?) SOURCE: L. Masanori, BRI