March 24, 2020
Thyssenkrupp Tower, Cobb County, GA
In July 2018, thyssenkrupp Elevator, one of the largest elevator companies in the world, announced that it would be building it’s $200 million North American headquarters close to The Battery Atlanta in Cobb County, Georgia.
Within batting distance of the Atlanta Braves stadium, the building, which would also host a state-of-the-art test tower, promised to become an ultra-modern addition to the city’s skyline.
Work began on 22 January 2020 and Mastclimbers LLC joined forces – once more – with GC Brasfield & Gorrie to provide a solution to the complex access issues this challenging build presented.
The most suitable hoist for the job was the Alimak Scando 650. With a top speed of 213 ft/min, this efficient machine uses 40% less power than earlier models and can handle payloads up 7,055 pounds per car.
We used a rolling tie to fix the construction hoist to the building working in tandem with the slip-form construction technique Brasfield & Gorrie were using to erect the core of the 420-foot tower at a rate of over seven feet per day.
Using a rolling tie, construction downtime is kept to a minimum, passenger transport is maintained for longer periods, there’s no need to reinstall the top landing gate structure and electrics, and structural loadings are kept consistently low as a temporary tie below the top tie isn’t required.
Rather than having a fixed structural connection between the hoist mast and the structure, there is a rolling frame connected to the mast in the same way as the hoist itself is connected.
The hoist cage rollers are connected to the front panel of the mast where drive is provided via the rack, while the rear panel of the mast is free for the rolling tie frame to be guided.
The fixed end is then structurally bolted to the slip-forming rig.
When nearing its maximum distance from the penultimate tie, a permanent tie will be hung on the newly poured concrete.
The tie wall brackets are connected to special cast-in threaded sockets and will remain until the slip-forming rig clears.
As soon as the rolling tie on the slip-form is at its minimum clearance to the pre-installed wall brackets, the permanent tie will be connected.