270 Brannan Street
San Francisco, CA
Structural and geotechnical engineers deeply collaborated to arrive at an innovative, integrated foundation and ground improvement solution for this LEED Platinum-certified Class A office building.
This Rincon Hill infill project is a 65-foot-tall office building with seven floors of rentable space, totaling 213,000 sf, surrounding a central atrium; a large roof deck; and a basement parking garage accommodating 12 parking stalls and 52 bikes.
Straddling a historic shoreline reclaimed in the 19th century, the project presented challenging goals for the design team, including mitigating soils liquefaction and lateral spreading hazards; developing a cost-effective foundation support solution; and assuring satisfactory seismic performance. Deep-soil mixing (DSM) combined with micropiles emerged as the most cost-effective solution to address the ground conditions. DSM panels mitigate liquefaction and act as foundation support system, while micropiles provide resistance to seismic overturning. This solution also allowed the use of efficient conventional spread footings.