Originally published by Gethin Thomas August. 27, 2020
122 Leadenhall Street, also known as the Leadenhall Building, is a skyscraper in London that is 225 metres (738 ft) tall. It opened in July 2014 and was designed by Rogers Stirk Harbour + Partners; it is known informally as The Cheesegrater because of its distinctive wedge shape similar to that of the kitchen utensil with the same name. (seen here on the left)
The new tower features a tapered glass façade on one side which reveals steel bracings, along with a ladder frame to emphasise the vertical appearance of the building. It also appears to anchor the tower to the ground, giving a sense of strength. Unlike other tall buildings, which typically use a concrete core to provide stability, the steel "Megaframe", engineered by Arup, provides stability to the entire structure and is the world's tallest of its kind. The base features a 30m high atrium which is open to the public and extends the adjacent plaza. The flat side of the building is also encased in glass, and houses the mechanical services – in particular the elevator shafts. These have been turned into an architectural feature in a vein similar to the neighbouring Lloyd's building – they deliberately show off the elevator machinery with bright orange painted counterweights and the actual elevator motors themselves.
It's construction had many unique features, due to the design and shape of the building. Due to the shape in profile the building at the back is 48 floors high while at the front it is less than 10 floors high. So imagine the weight distribution on it's footprint. It would quite literally tip backwards if not constructed properly to account for that massive weight difference.
"The building was predicted to move sideways to the north during construction. An innovative approach was deployed to counter this, known as ‘active alignment’. The structure was initially erected straight and movements regularly monitored. At a later point, adjustments were made to the ‘megaframe’ diagonals which pulled the building back sideways, reversing the gravity sway. This allowed the ‘megaframe’ nodes to be fabricated with a simple orthogonal geometry and improved the overall accuracy of construction."
Put simply every few floors as the building rose the steel framework already in place was adjusted and tightened to pull the back of the building forwards, correcting the vertical.
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