In addition to the vertical force of gravity, skyscrapers also have to deal with the horizontal force of wind. Most skyscrapers can easily move several feet in either direction, like a swaying tree, without damaging their structural integrity. The main problem with this horizontal movement is how it affects the people inside. If the building moves a substantial horizontal distance, the occupants will definitely feel it. Show The most basic method for controlling horizontal sway is to simply tighten up the structure. At the point where the horizontal girders attach to the vertical column, the construction crew bolts and welds them on the top and bottom, as well as the side. This makes the entire steel super structure move more as one unit, like a pole, as opposed to a flexible skeleton. For taller skyscrapers, tighter connections don't really do the trick. To keep these buildings from swaying heavily, engineers have to construct especially strong cores through the center of the building. In the Empire State Building, the Chrysler Building and other skyscrapers from that era, the area around the central elevator shafts is fortified by a sturdy steel truss, braced with diagonal beams. Most recent buildings have one or more concrete cores built into the center of the building. Making buildings more rigid also braces them against earthquake damage. Basically, the entire building moves with the horizontal vibrations of the earth, so the steel skeleton isn't twisted and strained. While this helps protect the structure of the skyscraper, it can be pretty rough on the occupants, and it can also cause a lot of damage to loose furniture and equipment. Several companies are developing new technology that will counteract the horizontal movement to dampen the force of vibration. To learn more about these systems, check out How Smart Structures Will Work. Some buildings already use advanced wind-compensating dampers. The Citicorp Center in New York, for example, uses a tuned mass damper. In this complex system, oil hydraulic systems push a 400-ton concrete weight back and forth on one of the top floors, shifting the weight of the entire building from side to side. A sophisticated computer system carefully monitors how the wind is shifting the building and moves the weight accordingly. Some similar systems shift the building's weight based on the movement of giant pendulums. UK-based Heatherwick Studio designed two irregularly-shaped towers that, when built, will grow upwards from a bottleneck into tall structures studded with balconies. The high-rise buildings are planned for Vancouver and will feature clusters of plants on their balconies, which many of the British architecture firm's recent skyscrapers also do. Find out more about the Vancouver skyscrapers ›  Walkie Talkie by Rafael Viñoly Officially named 20 Fenchurch Street after its location in London, Rafael Viñoly Architects' concave skyscraper is known as the Walkie Talkie for its distinctive form that has larger floor plates on its upper levels than those closer to the ground. While still under construction, the Walkie Talkie's gleaming glass facade acted as a curved mirror that overheated and damaged parked cars below it. Find out more about the Walkie Talkie › Greenpoint Landing by Jason Long and OMA Architecture firm OMA collaborated with architect Jason Long to design two adjacent residential buildings for Brooklyn's Greenpoint neighbourhood in New York. The pair of buildings are stepped to give the impression that the individual buildings were torn apart. While the northern tower gets smaller as it rises, the south tower increases in size as the skyscraper ascends. Slated to be complete by spring 2022, the Greenpoint Landing towers are currently under construction, and topped out in May. Find out more about Greenpoint Landing › Era by ODA Also planned for New York, American office ODA designed a 20-storey apartment building on Manhattan's Upper West Side that cantilevers outwards from a small footprint. Scheduled to be complete by next autumn, Era was designed to have a communal rooftop area, while the volume at the busy street level will require the least amount of space. Find out more about Era › Marsk Tower by BIG Architecture studio BIG designed a spiralling viewing tower for Denmark's Wadden Sea National Park that features a dramatic double helix structure. The tower is constructed so that visitors can navigate one way up and another way down via opposite staircases. Made from Corten steel, Marsk Tower gradually expands outwards from a seven-metre-wide base to a 12-metre-wide viewing platform that provides panoramic views of the surrounding marshland. Find out more about Marsk Tower › Camp Adventure tower by EFFEKT Another helical tower is located at Denmark's Camp Adventure, the country's largest climbing park. The Camp Adventure tower is accessed via a spiralling staircase that widens as visitors reach the top of the viewpoint. Copenhagen-based studio EFFEKT designed the wood and weathering-steel tower with an hourglass shape that is defined by the evolving curvature of the winding ramp and offers treetop sights of the landscape below. Find out more about the Camp Adventure tower › The Tulip by Foster + Partners British architecture practice Foster + Partners has proposed creating a 305-metre-tall viewing tower named the Tulip in central London. If constructed, the building would feature a long "stalk" topped with a bulbous viewpoint, or "flower head," that would house various public attractions. Find out more about the Tulip › Vessel by Thomas Heatherwick British architect Thomas Heatherwick designed Vessel, a honeycomb-shaped viewpoint in New York's Hudson Yards development that is formed from a web of interlinked staircases. Vessel's shallow arrangement of staircases creates an overall rounded structure that widens at each of the tower's new levels. After opening to the public in 2019, Vessel was closed on 29 July following a series of suicides committed at the viewpoint. Find out more about Vessel › Fifteen Fifteen by Büro Ole Scheeren Fifteen Fifteen will be a stacked residential skyscraper in Vancouver composed of boxy volumes that will jut outwards as the tower ascends. Designed by German studio Büro Ole Scheeran, the project is scheduled to be constructed from 2022 and will feature cantilevered observatories wrapped in floor-to-ceiling glass in order to provide residents with views of the Canadian city below. Find out more about Fifteen Fifteen › Belvedere Tower by René van Zuuk Belvedere Tower is a Dutch apartment building in the town of Hilversum that accommodates more living units on its upper storeys, thanks to its cross-shaped plan that expands as the tower rises. Architect René van Zuuk designed the apartment block to blend with the postwar apartment buildings surrounding it and respond to its location's urban character. Belvedere Tower includes a series of chunky balconies that cantilever from the structure, which looks as if it is growing outwards as it ascends. Can you feel tall buildings sway?The height, location, and wind speed surrounding a skyscraper help determine how much it will sway. The higher the floor, the more apparent the building's swaying will be. For example, the world's tallest building—the Burj Khalifa in Dubai—can experience up to two meters in back-and-forth sway from its 163rd floor. Is there a practical limit on the height of tall buildings?Yes, there are many limits. The heavier a building, the stronger its foundations need to be. In turn, that's limited by how deep it's possible to excavate and the land available to accommodate the building's footprint. Even the slenderest designs need larger bases as they get taller. How do engineers design skyscrapers to resist wind?How do engineers design skyscrapers to resist wind? By clustering steel columns and beams in the skyscraper's core, engineers create a stiff backbone that can resist tremendous wind forces. The inner core is used as an elevator shaft, and the design allows lots of open space on each floor. How much do tall buildings sway in the wind?There's also “wind sway”. A 1,000ft building may sway several inches on a day with normal winds. On days with 50mph wind, such a tower may move approximately six inches. In the rare event of 100mph gusts, this height structure could move up to two feet, the New York Times reported. |
