Sears Tower Skydeck Observation Boxes

John Kooymans

The landmark Sears Tower building in Chicago, Illinois generates income through its observation deck at the 103rd floor. Halcrow Yolles was approached by the building owners to help create four structural glass observation galleries that would project beyond the existing building façade and allow patrons to not only have a panoramic view of the city, but to also allow them to look straight down through a glass floor. This paper will look at the design challenges associated with the retractable glass structure ensuring that maximum views would be attained by deleting all structural steel beam components at the glass walls and glass floor interfaces. The assembly as a whole had to withstand extreme environmental loads and be detailed to retract within the building floor plate for maintenance purposes.

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