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Building Skyscrapers without tower cranes

The Exchange Tower in Detroit, Michigan is a 63-m tall building that showcases an advanced modular construction technique known as Liftbuild. This technique is a hyper-modular version of the "lift slab" technique, which has been around since the 1950s. The Exchange Tower was constructed without the use of cranes due to the elevated People Mover system running next to it, making it impossible to use tower cranes.

The Liftbuild construction system starts by preparing the foundations and building a number of central spines that house the stairs and elevators to the full height of the building. Each floor, starting with the roof, is built close to the ground with pre-fabricated parts, including the steel frame, concrete slab, facade, flooring, walls, electrics, plumbing, fire protection, and ducting. The Liftbuild team coordinates with various contractors to make sure everything is done on the ground, creating a factory-type assembly area for quick fitting and minimal lifting.

Once each floor is ready, it is lifted to the top of the spines using eight powerful strand jacks, with the top floors taking about 10 hours to lift. A proprietary bolted connection then locks the floor to the spines permanently. Each floor is a cantilevered design held up solely by the two spines, creating an open layout with no interior walls or columns blocking views.

The parent company of Liftbuild, Barton Marlow, led the design and construction of the Exchange Tower and financed the project as a demonstration of its capabilities. Liftbuild claims that its system can be up to 50% quicker and 10-20% cheaper than traditional construction methods, while also significantly reducing the number of workers needed.

The Exchange Tower represents the first use of the Liftbuild technology in America, although there have been similar lift-slab concepts used in the past. One such example is the 2018 construction of two 10-storey office buildings in Bangalore, India by TGE LLC.

In conclusion, the Liftbuild construction system offers advantages in terms of worker safety, cost, and speed, as well as a more open layout with no interior walls or columns. The successful completion of the Exchange Tower in Detroit serves as a proof of concept for the Liftbuild technology, setting the stage for its broader commercialization.

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