Photo by Tim Griffith Photography

The $21.7-million project included repairs and a seismic retrofit, returning the civic building to its former stature.

Atascadero City Hall was hit by a 6.5-magnitude earthquake in 2003. The upper rotunda twisted independently from the rest of the building, causing perimeter walls to peel away from the building, which is on the National Register of Historic Places. The structure was red-tagged because of the damage. The $21.7-million project included repairs and a seismic retrofit, returning the civic building to its former stature.

The existing foundation was stabilized beneath the original footings with concrete pile caps and 248 micropiles drilled up to 80 ft deep into bedrock. Exterior walls were reinforced with approximately 1.2 million tons of shotcrete and 40 tons of rebar.

To repair the upper rotunda, crews removed almost all of the cladding and rebuilt the structure with additional steel-and-fiber- reinforced polymer to minimize the amount of weight at the top of the building. In the upper dome, existing structural steel was horizontally and vertically braced, and the other framing members were retrofitted.

There were no drawings of the building available. Therefore, the design team used laser scanning and extensive visual inspection to plan the rehab.

"There were so many unknowns, that to come in under budget was an accomplishment," said one judge.

Judges were also impressed by the team's efforts to remove "unfortunate alterations" added over the years and restore many original architectural features.

Key Players

Construction Manager Bernards

General Contractor Diani Building Corp.

Owner City of Atascadero

Architect Pfeiffer Partners Architects

Structural Engineer Nabih Youssef & Associates

MEP Engineer Davidovich & Associates