4. DEFINITION and CLASSIFICATION
A Skyscraper is a tall continuously habitable building having multiple floors.
When the term was originally used in 1880’s it described a building of 10 to 20
floors but now describes one of at least 40 to 50 floors.
Tall buildings are also called High rise buildings. But term Skyscraper is often used
for buildings higher than 50m.
For Buildings higher than 300m the term super tall can be used. While skyscrapers
reaching beyond 600m are classified as Mega tall.
5. ORIGIN
The concept was originated in USA, in Chicago and
New York, where the space was limited and where the
best option was to increase the height of the building.
Home Insurance Building in Chicago was perhaps
the first skyscraper in the world. Completed in
1884; it was 42m (138 ft) high with 10 floors.
Equitable Building in New York, completed
in 1870 , it was 43m high with 7 floors is a
building of extra ordinary significance,
because it was 1st office building with
elevator.
HOME INSURANCE BUILDING
(CHICAGO) EQUITABLE BUILDING (NEW YORK)
7. LEAP 1:- ELEVATORS
The early Elevators
had one deadly
fault.
They are lifted using
a single rope and if
the rope broke;
nothing can stop
them from falling.
In 1854,
Elisha Otis from
Vermont along
with his sons
designed safety
elevator and
demonstrated it
in World’s fair in
New York city.
The first big obstacle to Skyscrapers is the Stair.
The obvious solution to the problem is Elevator.
8. EARLY ELEVATORS AUTOMATED SAFETY ELEVATOR
LEAP 1:- ELEVATORS
At top it consists of Leaf spring
attached to Metal Prongs on
either side which run across
Guide rails fitted with Metal
Teeth.
When the rope broke, The spring relaxes and forces
metal prongs into the teeth locking the Elevator in
place.
Without an safety elevator the Skyscrapers would be impossible.
9. LEAP 2:-MATERIALS
Another crucial development was the use of Steel Frame instead of Stone or Brick.
The Monadnock Building in
Chicago opened in 1893 is the
worlds largest office block at
that time with 16 floors.
The walls at the bottom were
whopping 2m thick to bear the
weight of Monadnock .
The structure was extremely heavy that it soon began to sink.
Eventually Half a meter of Bricks and Mortar disappeared underground.
10. LEAP 2:-MATERIALS
This made the architect of Monadnock , Daniel Burner to realize that Stone
was not a Building Material for Skyscrapers.
When Daniel Burner was planning Fuller Building in New York he designed it
with Steel Columns and Beams locked together into a Steel skeleton.
Steel is much stronger and lighter than stone.
Thus it could reduce the weight of the structure.
To keep the weather out Burnham could
simply hang Thin Masonry walls off steel frame
like curtains.
This is a new breed of Building.
The Modern Skyscrapers are built with Steel or
Reinforced Concrete frames.
Before using Steel Skeleton, one could build to a maximum
of 10 to 12 floors. But now sky was literally the limit.
11. LEAP 3:-HEAT
After development of Structural steel and Reinforced Concrete exterior
walls of Building were no longer required for structural support.
Hence Curtain walls are used in place of Masonry walls.
A Curtain wall system is an outer covering
of a building in which outer walls are Non-
Structural, but merely keeps the weather
out and the Occupants in.
As curtain wall is non structural it can be
made of light weight material.
When Glass is used, a great advantage is natural light can
penetrate deeper with in building.
But, the Glass walls allows Solar radiation into buildings along
with Light. This makes things uncomfortable inside building.
Solar and Thermal control Glasses are being used in Modern
Skyscrapers to make them more convenient .
12. LEAP 4:- SPEED
Prefabrication technology allowed giant Skyscrapers to grow
ever faster, which made them even profitable and desirable.
The problem with skyscrapers at that time is they took much longer time to build.
For construction of World Trade Center in New York Engineers
invented a much faster way of building Skyscrapers.
The solution they came up with is to prefabricate
sections of towers and assemble them.
Using Kangaroo Cranes from Australia they lifted up 50
ton prefabricated sections and placed them in
positions.
After assembling 3 floors , the bottom of crane is
released, jumped 3 floors up and locked back in place.
Using prefabricated sections and Kangaroo cranes
Builders managed to finish 3 floors every week.
In modern Skyscrapers like Burj Dubai new
technology called jump forming is used.
13. LEAP 5:-WIND
Building a skyscraper using a traditional steel skeleton
would have caused massive problems. The tall one skeleton
gets, the more susceptible to bending in high winds.
Architects of Sears Tower inverted a technology that would
beat wind. They shifted steel framework from inside of
building to outside. This is called “Exoskeleton” and made it
very hard for wind to bend the building. In Sears Tower, 9
such tubes locked together to make building rock solid.
As skyscrapers grown higher into the clouds they became exposed to a new enemy “THE WIND”.
A high speed wind can be extremely dangerous for a skyscraper. Air
rushes around the buildings and forms mini tornadoes called “Vortices”.
These areas of low pressure sucks the building sideways and taller the
building the more dangerous the vortices become.
To build 442m Sears tower in Chicago in firmly windy city engineers had to turn skyscraper inside out.
In Taipei 101, tuned mass damper of 728 tons is
used to stabilise the building from wind forces.
The Setbacks are
provided in the design
to seal the wind.
14. LEAP 6:-EARTHQUAKES
To survive in fast and violent earthquakes the
Taipei 101 needs elasticity. So designers made
their building rigid where it had to be and flexible
where it could afford to.
At heart of Taipei 101, they put 36 steel columns
filled with concrete that give building strength
while the columns stand firmly during an
earthquake the rest of structure is elastic, it can
flex and roll with punches.
On 31st march 2002, earthquake hits Taipei
101. The earthquake shattered smaller
buildings. But Taipei 101 was standing still.
The next big challenge to skyscraper is Earthquakes.
To make 509m tall Taipei 101
possible skyscraper had to
take another leap forward.
In 1999, the architects of world’s tallest
skyscraper at that time Taipei 101 in
Taiwan faced a big problem.
Taipei sits near the pacific ring of fire the most seismically active
area on earth. An earthquake hits the city roughly twice an year.
15. CONSTRUCTION PROCESS
After hardening of Concrete the mould along with kangaroo cranes jumps up with
help of Hydraulic pistons. In this way the structure is cast in place layer by layer.
The Kangaroo Cranes places the steel cages in special moulds
called Jump Forms and then Concrete is placed in it.
In Construction of Skyscrapers a technique called Jump forming is used.
30. ADVANTAGES
• All at one place.
• Accomodates population growth.
• Optimal usage of land.
• Tourist attraction.
• Serves as highest point for network tower
installation.
31. INTERESTING FACTS
• The Empire State Building stood as the world's tallest building for nearly 40
years.
• The Petronas twin towers in Malaysia are constructed on worlds deepest
foundations. Because of the depth of the bedrock, the buildings were built on
the world's deepest foundations. 104 concrete piles, ranging from 60 to 114
metres (197 to 374 ft) deep, were bored into the ground.
• The amount of rebar used for the Burj Khalifa in Dubai is 31,400 metric tons -
laid end to end this would extend over a quarter of the way around the world.
• The Skyscraper “India Tower” of 718m high with 126 floors was proposed for
construction in Mumbai and was cancelled during its initial stage of
construction due to Economic Reasons.
• The Burj Khalifa has 57 lifts within its incredible structure, including some
double decker lifts. Burj Khalifa also hold the record for the fastest lift, moving
at 18 m/s.
32. CONCLUSION
• 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.
33. REFERENCES
• “The Heights: Anatomy of a Skyscraper”
• “Skyscrapers: A History of the World's
Most Extraordinary Buildings”
• "Tall Buildings In Numbers Vanity Height".
Ctbuh.org
• http://www.emporis.com/statistics/worlds-
tallest-buildings
• https://en.m.wikipedia.org/wiki/Skyscraper