Structural engineering innovations were at the heart of a repositioning of the landmark 75 Rockefeller Plaza, former home of the Standard Oil Company. The project involved revitalizing the building’s façade and base metalwork, enhancing its lobby and retail spaces, and overhauling its mechanical systems and infrastructure.
To make way for new ground-floor retail and a more dramatic entrance and lobby, the team removed four columns at the ground floor, three of which supported existing transfer girders. When traditional approaches for transferring weight to accommodate the column removal proved too bulky and costly, the team adapted a structural approach common in bridge design: a composite-steel box girder. The solution met performance requirements and also coordinated with the planned sculpted lobby ceiling, which required the transfer members to be narrow and shallow.
Other innovations included the development of a unique “yolk” system, using 500-ton jacks, to preload a new steel box girder without the need for a temporary structure or shoring.
Building Team: Gilsanz Murray Steficek (submitting firm, SE) RXR Realty (developer, program manager) Kohn Pedersen Fox (architect) Robert Derector Associates (MEP) Orange County Ironworks (steel erector).
Details: 650,000 sf. Total cost: $150 million. Construction time: January 2013 to February 2017 Delivery method Design-bid-build.