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Building Type: Institutional
Original Structure Type: Unreinforced Brick
Retrofit System Type: Isolation
Year of Retrofit: 2002
Uploaded by: Private
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Hearst Memorial Mining Building

Hearst Memorial Mining Hall (built in 1907) is an imposing four-story structure originally made of unreinforced brick masonry with exterior cladding of granite masonry. Infill reinforced concrete floors were added to provide additional structural support and occupiable space in 1947. In a 1990 study, engineers found the following problems: the masonry brick walls were weak due to their lack of reinforcement; the floor slabs had insufficient connection to the masonry brick walls; the front façade, chimneys, terra cotta tile ceilings, and stone ornamentation could all fall during an earthquake. Knowing the building’s proximity to the Hayward fault, the selected retrofit solution was “base isolation.” This technique improves the seismic performance of the building by placing the building on bearings that is stiff in the vertical direction and flexible in the horizontal direction. Because the bearings are flexible horizontally, the ground can shake at a more vigorous rate than will be experienced in the structure above the bearings. By separating the building from the ground or “isolating” it with these bearings, the fragile components of the building like the façade, chimneys, etc. will likely remain undamaged during an earthquake. The retrofitted building is now supported on 134 rubber-laminated steel bearings (also called isolators) so the building is able to move 28 inches horizontally in any direction during an earthquake. These bearings are also very resistant to natural degradation. This retrofit system utilized the new concept of performance-based design, which surpasses building codes by tailoring a building’s design to its desired performance after an earthquake.

This University of California Berkeley building was retrofitted as a part of the SAFER Program (Seismic Action for Facilities Enhancement & Renewal) which systematically reviewed, prioritized, and constructed building retrofits for all UC Berkeley owned and operated buildings.

Retrofit Engineer: Rutherford and Chekene
Retrofit Architect: NBBJ