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Marin County Hall of Justice Seismic Retrofit   1  Following the 1989 Loma Prieta earthquake, a preliminary investigation of the historic Marin County Hall of Justice identified deficiencies that could cause significant damage to this structure during a future seismic event. In response, Crosby Group developed a seismic retrofit design that addressed and mitigated these deficiencies. However, the retrofit of the Hall of Justice was constrained by a multitude of design and construction issues. Most notable was the architectural sensitivity required for this renowned, historic structure, designed by Frank Lloyd Wright in 1966. This meant that the seismic retrofit elements had to blend effortlessly into the existing architecture. All new elements, especially those visible from the exterior of the building, required approval by the County’s Architectural Review Board. Additionally, since the building was to remain occupied, all construction work had to be performed at night or on weekends, and had to be scheduled to minimize disruptions to ongoing county functions. The resulting design included a combination of new and conventional methods including the addition of buckling restrained braced frames at the upper floors allowing for open spaces and concrete shearwalls at the lower levels to provide strength and stiffness. Additional innovative design methods implemented included the use of composite fiber materials applied to existing brittle elements for strength and containment, and the use of shock transmission units to tie building segments together during seismic events. LOCATION: San Rafael, CA CONSTRUCTION COST: $24 Million COMPLETED: 2003 OWNER: Marin County HIGHLIGHTS: Prime Professional Historic Structure Occupied Facility Copyright © The Crosby Group. All Rights Reserved.