350 Mission Street – Structural Engineering

The form, structure, and systems of this Class-A office tower are driven by the interrelated goals of environmental performance, material efficiency, and social engagement. Its soaring, glass-enclosed lobby—envisioned as an "urban living room"—aims to blur the boundary between the public and private realm, connecting the interior with the downtown San Francisco streetscape.

An innovative structural design lifts the first office floor to create the dramatic 50-foot-tall lobby. The 374-foot-tall cast-in-place concrete structure utilizes a central shear wall core as the sole lateral load resisting element. SOM used rigorous performance-based design methods to prove equivalency to prescriptive code design procedures.

To provide efficient, open office space and to support the urban living room at the base, the building uses an 11-inch-thick long-span post-tensioned concrete flat plate floor system. The structure forms a dramatic 30-foot-long, two-way cantilever at the building’s most prominent corner—allowing the base to be enclosed in more than 90 feet of glass panels that slide open to the street.