This presentation describes an innovative application of seismic isolation that permits the vertical
expansion of an existing three story reinforced concrete moment frame building in the China Basin area of San
Francisco with the addition of two new stories, while reducing seismic demands by introducing isolation bearings
between the existing structure and the addition. The speaker will present the results of the analyses, document the
design process for the application of this approach and discuss the design of the unique isolation system.
The existing building, which serves as the base for the isolated addition, is about 900 ft long and 100 ft wide with two expansion joints at approximately every one third of the length. The new addition is a continuous structure that bridges over the expansion joints and utilizes concentric braced frames for its lateral strength. This is truly a unique application of the art of base isolation, where the plane of isolation has been moved from the base of the building to the roof. Being the first application of this type in the United States, the project unveiled a unique set of challenges never encountered before in the design of an isolated structure.
The performance objective was that the existing building and addition provide a similar level of reliability against collapse or life safety endangerment as a new building designed to the current code. Three dimensional non-linear dynamic analyses were used to demonstrate that the supporting structure was able to safely withstand the additional mass of the new structure albeit in a non-linear fashion. Concepts of structural reliability using incremental dynamic analyses were also used to justify that the new addition is indeed beneficial to the performance of the existing structure. The City of San Francisco required a rigorous peer review for this novel project, which is currently under construction. Completion date for the project is mid 2008 with an estimated construction cost of $40 million.
Dr. Ronald L. Mayes is a pioneer in the application of base isolation technology in the United States. In
1982, he formed and became President of Dynamic Isolation Systems, Inc., a firm that pioneered, designed, and
supplied seismic isolation systems for over 90 base isolated bridges, and more than 30 base isolated buildings in
the United Sates, including USC Hospital, Oakland, and San Francisco City Halls.
Dr. Mayes was appointed Technical Director of the Applied Technology Council in 1976 and was Executive Director for the period of 1979-1981. He joined Simpson, Gumpertz & Heger (SGH), a structural engineering firm with more than 250 employees, in 2001 and is their in-house expert on the application of innovative technology.
Dr. Mayes leads SGH work in areas of base isolation and energy dissipation systems, testing programs and research and development activities. He has lead most of the Federal Highway Administration efforts over the past 25 years in developing seismic design provisions for highway bridges. Early in his career, he was heavily involved in major test programs of masonry construction and their implication on design codes.
Dr. Mayes has served as the EERI Secretary/Treasurer from 1999 until 2005.
Wednesday, APRIL 16th, 2008
10:30 AM EST
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Seminar sponsored by MCEER Networking and Education Programs, MCEER SLC and hosted by the Department of Civil, Structural and Environmental Engineering and the EERI Student Chapter at UB.
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