Everything Old Is New Again at San Francisco City Hall

Sep 1, 2002 12:00 PM

When the four-year, $300 million restoration of San Francisco's City Hall was completed, seismic protection was the main improvement, complemented by other upgrades designed to improve safety and security while keeping the historic structure intact.

When the Loma Prieta earthquake shook the structure of San Francisco City Hall in 1989, its 90,000-ton gilded dome was twisted like a bottle cap. To forestall the building's collapse, it was shored up temporarily to allow its continued use during restoration, and an agreement was reached to preserve the original architecture while upgrading it into compliance with current seismic and functional requirements.

For protection against future earthquake damage, the structure's concrete pilings were sawed through, and the building was raised slightly to insert 600 doughnut-shaped “shock absorbers” on which the building now “floats.” This suspension will dissipate earthquake motion and allow the City Hall to glide nearly 26 inches without shaking apart. The structure of the four-story, 500,000-sq.-ft. building was also reinforced extensively, with 1,200 tons of steel used to strengthen the dome.

While the building was undergoing this restoration, other improvements were also scheduled, including upgrading security, audiovisual and call systems and a sprinkler system.

One challenge was to ensure that the door hardware functioned properly to meet current code requirements without compromising the appearance of the building. In some cases, original hardware was rebuilt and refinished. Other doors received hardware that complemented the original décor.

The many wood doors that required exit devices throughout the building are well-equipped with Von Duprin 88 Series exit devices, which offer simple, traditional lines and durability. Exterior doors previously equipped with double-sided mortise deadbolts were converted to provide the improved life safety protection required by current codes.

To meet ADA standards, many doors were converted to out-swinging, and lever trim was added. Problems arose because the unit locks previously used in the building were no longer available. Moving some locks from less visible areas and adapting others covered most of the highest priority openings, says locksmith supervisor Robert P. Garabedian. The effort required rekeying hundreds of doors with the help of outside contractors to meet the move-in deadline, he says.

At the same time, doors in basement hallways and other areas without historic significance were equipped with Von Duprin 35 Series touch bar exit devices. These were often combined with electric strikes or latch retraction and door operators to achieve ADA-compliance.

Garabedian's department, part of the Bureau of Building Repair in the Department of Public Works, includes five locksmiths. The department is responsible for servicing municipal buildings in the county, including fire, police and libraries, as well as jails, the water and sewage facilities and assistance to other facilities with their own locksmiths. He says the City Hall project itself has required the full-time services of a locksmith.

The City of San Francisco's Bureau of Architecture was in charge of the restoration project. Heller, Mannus & Finger and Moy & Komorous-Towel provided architecture, and the general contractor was Huber, Hunt & Nichols.

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