One Market Street
San Francisco, California
Two stabilizing cores concealed within existing light wells strengthen this historic, Class-A office building while maximizing leasable space.
Constructed in 1917, the 11-story, 420,000-sq-ft building at One Market Street once served as the headquarters for Southern Pacific Railroad Company. The new owner sought to modernize and seismically retrofit the landmark, while preserving its historic integrity.
The building’s original structure was composed of a riveted-steel frame with infill masonry façade walls set upon a foundation of timbers driven into the deep deposits of bay mud. In addition to mitigating these antiquated systems, which provided little lateral bracing, the retrofit design also needed to address issues of poor soil conditions, limited access for construction, historic preservation, and space planning.
The seismic system that we proposed integrated structural needs with the architectural program. The design solution utilizes two hollow concrete towers—each 33 feet square and 150 feet tall—and two solid concrete shear walls. The towers, which were inserted into existing light wells, are supported by a foundation system of post-tensioned piers—drilled as deep as the building is tall—and connected to the existing structure through a network of collectors.
This solution increased usable space, avoided exposed bracing within leasable spaces, and accommodated the new mechanical systems—all assets for the owner of this historic, Class "A" office building in San Francisco.
Executed as Steven Tipping and Associates
1999 SEAOC Excellence in Structural Engineering, Award of Excellence
1999 SEAONC Excellence in Structural Engineering, Award of Excellence