A presentation on skyscrapers.

1. WELCOME
Presentation by:-
B.SAI KIRAN
(15761A0111)
G.SAI
(15761A0117)
LBRCE
CIVIL ENGG(2nd Year)

2. SKYSCRAPERS

3. MEANING AND DEFINITION
Meaning:-
A Building that scrapes (rubs) the sky.
Definition:-
• 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 supertall
can be used. While skyscrapers reaching beyond
600m are classified as Megatall.

4. 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 ofthe building.
1) Home Insurance Building in Chicago was perhaps
the first skyscraper in the world. Built in 1884; it
was 42m (138 ft) high with 10 floors.
2)a) Equitable Building in New York is a building of
extra ordinary significance, because it was 1st
office building with elevator.
b) The old Equitable Life Building was destroyed by
fire in 1912; and the new Equitable
Building replaced the old one and opened in
1915.
c) The height of Equitable Building is 164m (538 ft)
with 40 floors.

5. LEAP 1:- ELEVATORS
The first big obstacle to
Skyscrapers is the Stair.
The obvious solution to the
problem is Elevator.
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 Worlds fair
in New York city.
 Without an safety elevator
the Skyscrapers would be
impossible.

6. 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
storey.
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.
This made the architect of Monadnock , Daniel
Burnham 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.

7. 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.
• In 1947, when United Nations designed their head
quarters in New York, they wanted to cover the
building with glass. But they were in dilemma if it
would turn it into a heat house.
• An American engineer Willis Carrier cracked cooling
problem.
• He invented a machine that could cool hot moist air by
making it wet.
• Solar and Thermal control Glasses are being used in
Modern Skyscrapers to make them more convenient .

8. LEAP 4:- SPEED• 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.
• The Kangaroo Cranes places the steel cages in special moulds
called Jump Forms and then Concrete is placed in it.
• 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.
• Prefabrication technology allowed giant Skyscrapers to grow
ever faster, which made them even profitable and desirable.

9. LEAP 5:-WIND
• 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.
• 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.
• The setbacks are provided in design of building
to seal the wind in modern skyscraper.
• In Taipei 101, tuned marks damper of 728 tons
is used to stabilise the building from wind
forces.

10. LEAP 6:-EARTHQUAKES
• 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.
• Earthquakes are really strong when compared
to winds. Wind loading will rarely break a
large building, but for a earthquake its quite
easy to do that.
• 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.

11. EMPIRE STATE
BUILDING
Height :- 443 m (1,454 ft)
Floors :-102
Opened:-1st May 1931
Location:-USA (New York)

12. PETRONAS
TWIN TOWERS
Height :- 451.9 m (1,483 ft)
Floors :- 88 (+5 below ground)
Opened:-1st August 1996
Location:-Malaysia (Kuala Lumpur)

13. TAIPEI 101
Height:-509.2m (1,671 ft)
Floors :-101
Opened :-31st Dec 2004
Location :-Taiwan(Taipei)

14. SHANGHAI TOWER
Height :-632-m (2,073 ft)
Floors :-127
Opened :-18th Feb 2015
Location:-China(Shanghai)

15. BURJ KHALIFA
Height :829.8m(2722ft)
Floors :-163
Opened :-4th Jan 2010
Location :- UAE (Dubai)

22. 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.
• The Jeddah tower in Saudi Arabia of 1Km height
is under construction and by 2020 it will be the
worlds tallest Skyscraper.