Renovation and Vertical Expansion Breathes New Life into 633 Folsom

Built in 1967, the original building at 633 Folsom Street in San Francisco was developed by The Swig Company as a modern office building for the telecommunications giant AT&T. Fast forward to the 2010s: AT&T had long since moved out of the space, and the aging midrise building was no longer attractive to tenants looking for a corporate home in San Francisco’s South of Market (SoMa) district. So instead of selling the outdated building or redeveloping the site with new construction, Swig saw an opportunity to give the building a facelift, nearly double its square footage and height, and make it the star of their portfolio. The vision for the new building included a vertical expansion of the existing structure wrapped in a striking new skin. To make this distinctive concept economically feasible required a dedicated design and construction team capable of an equally unique approach.

1951 Harbor Bay Parkway, a new building (Figure 1) located in Alameda, CA, was developed privately for use as commercial office space by a life-sciences company. The project provided the opportunity to utilize an innovative approach for seismic bracing that provides improved performance and cost-effectiveness over conventional braced-frame systems. The system uses concentric buckling-restrained braces (BRBs) in conjunction with a vertical mast or strong-back to reduce drift, eliminate weak stories, and increase redundancy. The yielding BRBs work in tandem with an elastic mast frame to create controlled rocking behavior that provides more resiliency and improved protection for the building frame, cladding, and interior construction.