Thrill-seeking tourists will have a new destination this June, when the renovated U.S. Bank Tower is slated to reopen after a $50-million facelift. One unusual addition to the 1989 I.M. Pei-designed building is a 36-foot long, fully enclosed glass slide, cantilevered some 1,000 feet above ground between the building’s 69th and 70th floors.
The concept for the Skyslide came from the Singapore-based company OUE Limited, which purchased the building three years ago. Engineering firm M. Ludvik & Company designed and realized the first-of-its-kind structure. Chief engineer Michael Ludvik says the building’s tiered and angled facade required the that the slide be constructed in two pieces: an elbow piece, turning nearly 90 degrees as it emerges from the 70th floor entrance, and a straight section that sends visitors sliding down to the 69th floor landing.
Ludvik explains that the bent portion of the slide was chemically strengthened. “It’s got the yield strength in excess of normal structural grade steel,” he says, “but it’s also optically clear with no distortion.” The rest of the slide is tempered and laminated with a special structural interlayer typically used for hurricane glazing.
The walls of the slide bear gravity loads, while the roof and floor are lateral support systems for seismic and wind activity, explained Ludvik. High-strength, aerospace-grade stainless steel hardware bolt the Skyslide together, while a series of pins allow the structure to move with the building. “We don’t want the slide to hold back the building,” says Ludvik.
The structure is designed to withstand a 2.4g seismic acceleration, and can support 12,000 pounds of weight—though operators will only allow three riders to enter at one time.