SFO Air Traffic Control TowerSan Francisco International Airport, California

The new 220-foot tall control tower combines striking architecture with cutting edge seismic design. As part of the 45% bridging documents team, Joe and Lawrence led the seismic design of the tower and devised the inventive solution of a post-tensioned core wall with a force-limiting backstay into the base building.  The unique design meets the demanding FAA criteria for extreme earthquakes while minimizing foundation and excavation costs and schedule impacts.  The project is the first control tower and the first FAA project to use performance-based seismic design, the first FAA tower to use a design-build process, and it is the tallest structure built to date that uses vertical un-bonded post-tensioning.   Andreas carried out state-of-the-art seismic hazard and nonlinear soil-structure analyses of the deep bay mud site.

In addition to the efforts of Joe, Lawrence, and Andreas on the 45% seismic design, Maffei Structural Engineering led the structural engineering peer review in the design-build and construction phases of the project.

San Francisco Chronicle architecture critic John King wrote: “No Bay Area building shows the engineered reality of today’s architectural scene—or rather, keeps it under wraps—quite like the new flight control tower at San Francisco International Airport. The first impression is effortless, a flared silver beacon … What we don’t see is the work behind the lyrical flourish: a concrete spine rising from a concrete mat 7 feet thick, concealed by the aluminum skin and topped by 75,000 pounds of steel weights calibrated to thwart high winds and earthquakes. With all these requirements, it’s easy to imagine a brawny tower hulking over SFO, rather than the curvy cone sliding up into the sky. The efficiency with which the tall structure fits into the tight site is a tribute to the engineering firms involved: Walter P Moore, Rutherford + Chekene, and Maffei Structural Engineering.”