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San Mateo County "Old County" Courthouse Seismic Retrofit   1  2  3  Survivor of two major earthquakes (1906 and 1989) the Old Courthouse building (Circa 1902) embraces several distinctive features, including the largest stained glass dome on a public building on the West Coast, elaborately decorated art deco courtrooms and un-reinforced masonry walls with sandstone veneer. This historic structure sustained nearly $3 million in damage during the Loma Prieta earthquake. Shortly thereafter Crosby Group was retained to design and implement the extensive seismic retrofit required to restore the building to full public use. Challenges included protecting the architectural features and allowing some limited use of the building while performing the retrofit. Due to restricted access to the walls from the outside of the building, the unreinforced masonry was structurally enhanced from within, using composite fiber reinforced polymer (FRP). To protect historic tiled floors, slab-to-wall shear transfer was strengthened with FRP installed from the underside of the slab. In addition, an innovative steel transition piece was implemented to provide force transfer. This new composite system was successfully tested at UC San Diego prior to implementation. This retrofit design method resulted in substantial savings to the County (over a comparable conventional approach) and greatly reduced disruption from demolition. LOCATION: Redwood City, CA CONSTRUCTION COST: $3 Million COMPLETED: 1997 OWNER: San Mateo County HIGHLIGHTS: Prime Professional Historic Structure FRP Composite Design Copyright © The Crosby Group. All Rights Reserved.