Costly Seismic Retrofit Is Needed at Pasadena City Hall, Study Finds

A seismic retrofitting that may cost more than $54 million is needed to prevent Pasadena’s beaux-arts City Hall from partially collapsing and endangering lives in a major earthquake, according to a report to be presented to the City Council on Monday.

The Mediterranean-style structure--known to millions through its cameo appearances in films and television--would be damaged beyond repair by a major quake, warns the report based on a city-commissioned seismic study.

The question is not whether to retrofit, but on what scale, City Manager Philip Hawkey said Friday.

“There are some frightening words in the report,” Hawkey said. “If you’re sitting in one of these meeting rooms or walking down the hall, you could be in real jeopardy.”

The City Council will be presented with four possible options for strengthening City Hall. The cheapest solution, at $33.4 million, would save lives but would leave the 69-year-old structure unusable without extensive repairs after a major temblor. The most expensive option involves mounting the building on shock absorbers and filling the open arcade on its east side with a three-story wing.

Hawkey said the city--which is experiencing severe financial problems--must consider putting a bond measure on the ballot in the next two years to fund one of the solutions. To that end, he will ask the council Monday to begin a series of public outreach meetings to arrive at the best solution.

According to the computerized seismic study, the landmark’s walls could cave in, corridor columns could fail and the baroque dome could collapse on the floors below during a magnitude 7 quake on a local fault or a magnitude 8 temblor on the San Andreas fault.

Designed in the style of London’s domed St. Paul’s Cathedral by architects Bakewell & Brown, the City Hall is a rectangular structure surrounding a large courtyard with cloistered corridors and Alaskan marble stairways, capped on its west side by the dome.

Constructed in 1926-27 at a cost of $1.34 million, it was considered at the time to be among the strongest buildings in the area. But standards change, and the risk analysis by Forell/Elsesser Engineers showed that work needs to be done to improve seismic safety.

The four options suggested by Forell use shear-wall and base-isolation techniques to protect the structures from intense shaking. The base-isolation technique has been used to strengthen city halls in Oakland and San Francisco.

Shear walls fill in spaces between columns and beams to provide increased resistance to lateral force. The more expensive base-isolation technique reduces shaking through the placement of rubber shock absorbers below the building’s columns.

The $54-million alternative would use the base-isolation technique, adding a three-story wing in the east arcade area that would tie the various elements of the building together.

Robert Reed, the city’s capital projects administrator, says when it comes to quake protection, you get what you pay for: “In terms of seismic safety and preservation, the most expensive base isolation option is the best, but also costs the most.”

Others disagree.

Thomas Heaton, of the U.S. Geological Survey’s Pasadena office, said a base-isolation system could be overwhelmed in a major earthquake, and shear walls might perform better.