WHAT IS SKYSCRAPERS ?

• Skyscrapers are known to be super tall building either residential, work place or of mix use.
• They are now tends to coincide with major downturns in the economy.
• Today the number of skyscrapers that are being built all around the world are increasing where the land is highly expensive (as in big / metropolitan cities) as they provide high ratio of floor space to be used to per unit area of available land.
• Skyscrapers are a category of a high-rise building which are habitable buildings higher than a height of 150m(490ft) or roughly 45 floors.
• The concept was undoubtedly originated in the USA, in Chicago and in New York, where space was limited and where the best option was to increase the height of the buildings.

• The crucial developments for skyscrapers were steel, reinforced concrete, water pumps, and elevators. Until the 19th century, buildings of over six stories were rare.
• So many flights of stairs were impractical for inhabitants, and water pressure was usually insufficient to supply running water above about 15 metres (50 feet).
• The weight-bearing components of skyscrapers differ substantially from those of other buildings.
• Buildings up to about four stories can be supported by their walls, while skyscrapers are larger buildings that must be supported by a skeletal frame.
• The concept of skyscraper started from a building called Home Insurance Building in Chicago which was just 10 storey high, in 19th century and now we see buildings with floors as many as 163 I.e. in Burj Khalifa, Dubai
• Further buildings above 300m(980ft) are referred as SUPERTALL.
• And buildings higher than 600m(1960ft) are called MEGATALL

WHY BUILD SKYSCRAPERS ?

In some cities the usable land is very scare, build higher could maximize the land use rate- First, Dubai seemingly has massive land to build the buildings, but actually usable land is rare, the inland desert is too hot for living, they have to build the building in waterfront spaces and building taller to maximize the space. For this they also build many canals. This is also the reason that Palm islands and the World islands are being developed. They do this for increasing the usable land. Additionally tall buildings should be built before the low-rise buildings, by this way can avoiding the troubles and obstructions come from the NIMBYs in the future.

Earth quake actually don't affect the security of skyscrapers- The earthquakes in Japan and some other regions actually don’t affect the security of tall buildings, high-rise buildings have been proved to be safer than the low-rise buildings, those buildings collapsed in earthquakes are all low-rise buildings, we never heard a hundreds meters tall building collapsed because of earthquake, with current technology, an 1-kilometer tall hyper-tall tower can resist an earthquake of 9 on Richter scale, in technique earthquakes don’t restrict the height of a building at all.

Skyscrapers can beautify and modernize the cityscape- In fact the seeming necessity is not the only factor considered by skyscraper developers.
What differentiate us human being from animals is that we are not only after necessity of survival, we

If we just consider what they call necessity then the different styles and colors of our clothes is not needed any more, that is the spiritual pursuit of human make us need those different and colorful styles, and tall building is like such a style, to have a hyper-tall tower added to the city could enriching the skyline to make the cityscape more attractive. Maybe this is why today many star architect is designing skyscrapers more than the traditional buildings.

MATERIALS FOR SKYSCRAPERS ?

• REINFORCED CONCRETE is one important component of skyscrapers.
• It consists of concrete (a mixture of water, cement powder, and aggregate consisting of gravel or sand) poured around a gridwork of steel rods (called rebar) that will strengthen the dried concrete against bending motion caused by the wind.
• Concrete is inherently strong under compressive forces; however, the enormous projected weight of the Petronas Towers led designers to specify a new type of concrete that was more than twice as strong as usual.
• This high-strength material was achieved by adding very fine particles to the usual concrete ingredients; the increased surface area of these tiny particles produced a stronger bond.
• The other primary raw material for skyscraper construction is STEEL, which is an alloy of iron and carbon. Nearby buildings often limit the amount of space available for construction activity and supply storage, so steel beams of specified sizes and shapes are delivered to the site just as they are needed for placement.
• Before delivery, the beams are coated with a mixture of plaster and vermiculite (mica that has been heat-expanded to form sponge-like particles) to protect them from corrosion and heat.
• After each beam is welded into place, the fresh joints are sprayed with the same coating material. An additional layer of insulation, such as fiberglass batting covered with aluminum foil, may then be wrapped around the beams.
• To maximize the best qualities of concrete and steel, they are often used together in skyscraper construction. For example, a support column may be formed by pouring concrete around a steel beam.
• A variety of materials are used to cover the skyscraper's frame. Known as "cladding," the sheets that form the exterior walls may consist of glass, metals, such as aluminum or stainless steel, or masonry materials, such as granite, marble, or limestone.

IS SKYSCRAPERS EARTHQUAKE PROOF ?

• Earthquake are one of the most destructive forces of nature. Structures can suffer severe damage when an earthquake strikes.
• That's why, seismic loadings must be taken into account when designing structures, especially skyscrapers.
• The more lightweight and flexible a building is, the better it can withstand the lateral (sideways) forces of an earthquake.
•  Skyscrapers are built around a steel frame that supports the weight of the walls and floors.  
• Regular buildings use the walls to support the weight of the house or other structure, but in a skyscraper the weight of all those upper walls would be too much for the lower walls to support.  
• Steel makes tall buildings possible.
• Skyscrapers are placed on a foundation designed to absorb vibrations from earthquakes.  
• Architects design flexible springs and cushioned cylinders to act as shock absorbers. 
• A shake table is a device used to determine how well a building will react to earthquakes.  To see how well structures will react to earthquake shocks, building models are placed on massive outdoor shake tables and subjected to an array of ground motion energy.

CONCLUSION

• The SKYSCRAPERS are known to be super tall building either residential, work place or of mix use.
• They are not built just for the economy of space, they are considered to be symbol of city’s economic power.
• The first skyscrapers would have been typically an office building of more than 10 stories.
• The building up to about 4 stories can be supported by their walls, while skyscraper’s are larger buildings that must be supported by skeleton frames.
• In just over 130 years the Skyscraper conquered all forces of nature using power of Human ingenuity.
• Learning from Failures and making advancements made Skyscrapers grow from 40m to 830m and still counting.
• The Skyscrapers shows economic power, Will power and Technical power of a nation.

ARTICLE BY-

VAISHNAVI MAYEE