Earthquake Dampers Used for Seismic Retrofit of Building in San Francisco

by Eduardo A. Fierro,
Cynthia L. Perry,
Hassan Sedarat,
Roger E. Scholl,

Document Type: Proceeding Paper

Part of: Structural Engineering in Natural Hazards Mitigation


For the first time ever in the United States, earthquake supplemental damping devices have been installed in a building in San Francisco. The devices used are Added Damping and Stiffness (ADAS) elements which consist of steel plates that deform plastically during severe earthquakes to dissipate energy. The ADAS elements were used with steel chevron braces as part of the seismic retrofit scheme for a two-story, non-ductile concrete frame structure built in 1987. The building suffered both structural and non-structural damage during the 1989 Loma Prieta Earthquake and appeared to be a life safety hazard for a major earthquake. The ADAS retrofit scheme was selected over other more conventional schemes, in part because the design seismic force could be limited to the capacity of the existing foundation system. The paper summarizes the seismic analyses performed (linear and nonlinear), unique design details, the permit approval process, and final construction.

Subject Headings: Seismic design | Earthquakes | Damping | Seismic tests | Seismic effects | Rehabilitation | Earthquake resistant structures | Structural analysis | California | United States

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