Oakland’s majestic 80-year old City Hall received innovative quake protection during this retrofit project. This Beaux-Arts style building sustained heavy damage during the 1989 Loma Prieta earthquake, prompting critical seismic upgrades. Listed on the National Register of Historic Places, the Oakland City Hall is a historic landmark consisting of 18 stories with a steel framed structure and brick/stone perimeter. An additional 1,000 tons of steel and rubber “base isolators” were installed during this project helping protect this building from movement in the event of another large earthquake. This was the first time base isolators “20 inches thick and 2 to 3 feet in diameter” were added to an existing Bay Area building.
Signet provided special inspection and materials testing services related to reinforced concrete, proof load testing of anchors and dowels, shotcrete, shop and field welding/structural steel; in addition to other special investigations.