The Contra Costa County Administration Building, which replaced the outdated McBrien Administration Building, features a more efficient and community-friendly space and serves as a new focal point for the downtown area and surrounding community.
The four-story, 71,000-square-foot building houses office space for a variety of county departments, and a large assembly chamber on the first floor that serves local government and community interest meetings. The second floor serves as employee spaces, with the third and fourth floors providing offices, conference rooms, work stations and support spaces for the county.
We provided structural design services to Fentress Architects for the design-build building, which was completed in 2020.
- The structure consists of a deep pile foundation system, due to soft soils and high water table at the site location, which is situated close to Carquinez Strait. The above grade portion of the building is a steel special moment resisting frame ConXTech superstructure.
- With input from the team’s geotechnical engineer, the foundation solution was to tip the auger cast displacement piles into bedrock, to ensure that the building would sit on a solid base that would resist settlement.
- The site is located downgrade and at the intersection of Pine Street and Escobar Street. This presented a challenge for the team when planning for the appropriate ground floor elevation datum, due to rainwater creating a constant stream flowing down Pine Street and terminating at the entry of the Administration Building. The solution was to raise the building and strategically place a storm drain, to prevent flooding of the ground floor during rainy seasons.
- An additional challenge was providing a more durable and cost-effective exterior skin material that differed from the bridging architect’s proposed material of stucco. The team proposed a glass fiber reinforced concrete (GFRC) paneling system, as a more durable and maintenance-free alternative.