What is it like to whiz through a glass slide 1,000 feet above Los Angeles with nothing to hold on to other than a gray wool mat? The experience is so terrifying one would be forgiven for blocking out the memory entirely—but, thanks to the structural engineering capabilities of Brooklyn-based M. Ludvik Engineering, it is also incredibly safe. “We tested the pants off of absolutely everything,” Michael Ludvik, a structural engineer, told The Architect’s Newspaper as he discussed the structural design for L.A.’s newest thrill-seeking-tourist attraction, the Skyslide at OUE Skyspace L.A.
OUE Skyspace is part of a Gensler-designed, $60 million overhaul of the public areas of the 1,018-foot-tall, Pei Cobb Freed & Partners–designed U.S. Bank Tower; the renovations include a new ground-level plaza and lobby and, on the 54th floor of the tower, a snaking labyrinth of “digital interactivity” spaces, with moody hallways, panoramic video displays, and movement-sensitive light installations.
The real big-ticket item, however, is the OUE Skyspace $8-per-ride Skyslide, a 1¼-inch-thick glass-panel slide that exits the building’s envelope at the 70th floor, curves out over the city 1,000 feet below, and swoops back onto an outdoor terrace at the 69th floor, where the rider is unceremoniously dumped onto a red, padded mat. Ludvik explained, “The majority of the glass is tempered and laminated with a special structural interlayer called SentryGlas [made by Kuraray], which is the same product used for hurricane glazing in Miami-Dade County. We also have some glass with a complex bent geometry, where tempering was not possible, so we chemically strengthened the glass to be as strong as steel.”
It is no wonder that the slide, located as it is in a seismically active region, atop a building designed to sway as many as 30 feet during an earthquake, was engineered with a complex array of articulated, “soft touch” connections, containing ball joints that allow the slide to move independently of the massive building, that can carry a purported 40,000 pounds of pressure per connection (that’s the weight of a New York City subway car). “It would be scary as hell, but the glass wouldn’t break,” Ludvik said of the unlucky experience of riding the slide during an earthquake. “There is a system of pins which allow the glass to pivot and to be undamaged by the building’s inelastic seismic movements, plus a 2.4 g-force seismic acceleration capacity, all with a large factor of safety. This thing is a machine as much as a structure.”
Since each sheet of glass requires a structural joint that not only creates a point of potential structural weakness but, for the slide user, also the opportunity for a bumpy ride, Ludvik and his team designed Skyslide using Nastran, a stress analysis software used by NASA, to include as few pieces of glass as possible. They also worked with a complex, multinational team of fabricators to complete different portions of the slide. Renowned, China-based industrial-glass manufacturer North Glass fabricated the straight run of the slide, while the Italian company Sunglass crafted the curved portions.
Also important to the design of the slide were maintenance and cleaning operations, concerns about which resulted in the installation of operable windows along the tower’s facade facing the inboard side of the slide, so a traditional window-washing rig can reach it. “I will let you know how it all works after they hang me off the side for the first maintenance inspection,” Ludvik said.
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