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Topic Last Updated on 16-07-2024
Post on topic: Skyscraper.
Cast-Iron Solution
The use of ordinary bricks places significant limitations on structural design. The higher the building, the greater its weight, and the more pressure is placed on the load-bearing walls of its lower sections. As a result, such a structure may deform and eventually collapse. One way to prevent this would be to increase the thickness of walls, as was done when designing the 16-story Monadnock Building in Chicago in 1891. This “high-rise” had 6-ft thick walls in the lower stories, which obstructed natural light: sunlight could hardly penetrate the narrow, deep-set windows. Thus, other solutions were needed. As a result, architects turned to a new construction material — cast iron.
Cast iron is a relatively light, high-strength material. The first high-rise built using cast-iron I-beams was a seven-story building erected in 1801 in Manchester, UK. Its design created a type of framing structure that held most of the building’s weight. The Crystal Palace, built to house the Great London Exhibition of 1851, was the first structure ever to combine a durable yet light frame made of cast iron and wood with extensive use of plate-glass. The building, which resembled a giant greenhouse, could accommodate up to 14,000 visitors.
The Birth of Skyscrapers in Chicago
But it was the city of Chicago at the end of the 19th century that saw the launch of high-rise construction on a large scale. A metal frame as a load-bearing structure, combined with relatively thin brick walls, became the hallmark of the 138 ft-tall Home Insurance Building. This 10-story skyscraper was designed by architect William Le Baron Jenney in 1883 and featured the extensive use of rolled-steel L-shaped beams. Over the next 12 years, several other giants were built in Chicago, including the 10-story Rand McNally Building and the 20-story Masonic Temple. The steel structures were modified to withstand the wind load — architects used diagonal bracing in the planes of the outer wall frames, creating a vertical diaphragm wall.
Louis Sullivan’s Principles
How to Build a Skyscraper
Naturally, we’ll start with the foundation. In high-rise buildings, the foundation must withstand extreme loads up to several hundred thousand tons. There are three foundation types currently in use: raft, piled, and combined.
Skyscraper | Foundation types
Advanced Foundations and Structural Systems in Modern Skyscraper Construction
Combined piled raft foundations allow for an even distribution of a heavy load between the deep soil layers (using long supporting piles) and the inter-pile space (with the help of a massive raft). This kind of foundation supports the world’s tallest building, the Burj Khalifa. Two hundred 155-ft piles, each 5 ft in diameter, distribute the load across relatively soft soils. At the same time, on the upper part of the foundation, the concrete raft transfers the pressure to the outer layers of soil. An unusual solution was adopted in the construction of Germany’s Post Tower: the piles are separated from the main reinforced concrete slab with a synthetic gasket. The construction compensates for the deformation of soft soils.
Let’s move on to the load-bearing walls, or rather the load-bearing structures — the “skeleton” of a skyscraper. They are usually made of steel pipes, rolled steel sections, or welded connections. The welding of the “skeleton” isn’t typically performed at the construction site — instead, everything is assembled from prefabricated units, similar in principle to construction set toys. Cranes deliver the structural elements to the assembly area, where construction workers use either bolts or rivets to connect them to the building’s core.
Next, it’s time to install the floors, which also vary in design. Some floor systems for high-rise constructions include steel grating systems, reinforced-concrete plates, or beam-and-girder constructions. Additionally, daylight illuminance requirements, called the daylight factor, dictate maximum room depth. Building regulations associated with providing adequate daylight for high-rise buildings may vary from country to country.
So, the skeleton is complete: the foundation has been laid, the walls and floors are in place. All that remains is to install external panels made of glass, reinforced concrete, plastic, and insulation, and, finally, install the roof. But there are some important nuances.</>
Skyscraper | Essential Details
The residents of tall buildings typically take little interest in the technical aspects of high-rise construction. After all, there are more pressing issues: how do you get to the upper floors? Few people want to climb the stairs. The most obvious solution is elevators, but the ones used in skyscrapers are special. The first modern passenger elevator was installed in a New York department store in 1857. In the second half of the 19th century, engineers refined the design of the early steam-driven elevators, making them safer and easier to operate. Still, their lift speed didn’t exceed 0.45 mph. This is why the first electric elevator, invented by the German engineer Werner von Siemens in 1880, was a history-changing development.
Currently, elevators in such skyscrapers as the Petronas Towers (Kuala Lumpur, Malaysia), the Jin Mao Tower (Shanghai, China), and the International Finance Center (Hong Kong) can be as fast as 15.7 mph — they take just one minute to get to the 50th floor! In the Taipei Financial Center, passengers ascend (or rather, fly) at an average speed of 37.6 mph. The speed of descent, however, is only 22.4 mph.
Elevator components
