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MODE OF CONSTRUCTION OF THE WORLDS TALLEST BUILDING- BURJ KHALIFA

Presented by:-Joji Mathew

Civil Engineering Department

Marian Engineering College(TVM)

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Contents Introduction Excavation Casting of the

structure Elevators and

escalators Cladding of the

tower Speed of

construction

Wind Shape Buttressed

core Earthquake Evacuation Environment

friendly

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Introduction The Burj Khalifa is the ever built tallest man made structure. This tower rises in the sky to 828m carrying 162 floors. The Burj took 6years for its construction and was completed in the year 2010. For erecting this city in the sky several new technologies had to be used.

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Excavation

The soil stratum of Dubai is very week so they had to excavate up to 50m deep to get a hard rock structure

But the rock that they found was fragile and saturated with ground water

So that any hole made will be cured immediately

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Excavation cont……

The engineers filled this with a viscous polymer slurry

This pushes the rock and the ground water to the edges of the boreholes to keep it open

This slurry is denser than water and liter than concrete, so that when concrete is pumped the concrete displaces the fluid and forms the

foundation. 194 piles were constructed for avoiding the sinking of this structure.

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Casting of the structure

The casting of the whole structure is mainly done by two materials

1. Concrete 2. Steel Over 30,000 tons of steel were used About 250,000 m2 concrete was also

used The reinforced concrete acts as the

backbone of the whole structure

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Elevators and escalators

The Burj can accommodate about 35,000 people at a time

Consist of 57 elevators and 8 escalators The biggest elevator carries about 46 people

at a time These elevators travel at a speed of 35km/hr The Burj has a service/firemans elevator

which have a capacity to hold about 5,500kg And this is the worlds tallest service

elevator.

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Cladding of the tower The Burj is claded with high-tech glass

which forms as a curtain wall If the whole cladding has to be done with

high-tech glass which will cost about 100 million dollars

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Test for the cladding against storm

The cladding should withstand the heavy sand storms that with in include water and dust

Prototypes were selected and with the help of propellers artificially created storm was allowed to hit the glass panels at

a greater speed The glass panels withstands the storm up to 75km/hr

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Glass panel

The solar contains UV radiations as well as IR radiations

So that the glass panel consist of two layers The outer layer is coated with a thin layer

of metal so that it reflects the UV radiations The inner layer is coated with thin layer of silver so that it reflects the IR radiations

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Glass panel cont…..

Arrangement of glass panels in such a manner will make the building a green house

The hot air will only be absorbed by the glass panels and wont allow it to go out

So that air conditioners were provided for the cooling of the air and fresh air

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Speed of construction As the building has to be built more than

half a km, it had to challenge many factors that haven't faced by any other building

Has to be completed with in the short period limit

So the time was money For erecting such a structure in the sky

steel and glass panels have to be raised This was done by cranes

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Cranes The cranes consist of two plates on the

two sides It could jump from one floor to the

another So that they were called the kangaroo

cranes So as to speed up the construction the

RCC walls was done in a simple and clever engineering way

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Casting of RCC walls For simplicity and speed the engineers made no.

of steel cages These cages were inserted to the formworks that

can be moved easily After installation of cages concrete was filled in

these formworks Only took 12hrs for the setting of concrete After setting the concrete the formworks would move to the next level with in 2hrs

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Concrete used High performance concrete(HPC) Low permeability High durability C80-C60 cube strength concrete was used It includes fly ash, Portland cement Two largest concrete pumping machines in the

world were used for this purpose For reducing cracks due to high temperature

concreting was done only at night So that air is cooler and humidity is higher with

ice added to the mix

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Concrete used cont…..

The pump needs 630HP to pump about 25000tons of concrete

It had took about 14mints for reaching the concrete to the 150th floor

They completed every new floor in 3 day

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Wind Every year the storm attacks Dubai As the building grows much higher to the

sky the top will be badly affected by the wind

This causes a sway at the top floors of the building

So that they studied many other skyscrapers

The buildings must be in a definite shape

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Shape They made a study on the Sears tower at

Chicago The Sears tower had a layer of steel, and an another layer of steel which forms an exoskeleton to the building 9 such blocks were used in this Sears tower in definite shape So that the building was made rock solid

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Shape cont….

Giving the Burj a exoskeleton was not a easy task

So they designed the Burj in a triangular shape

So that this was suitable to deflect the wind to different ways

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Buttressed core The three wings allow for greater

building height by buttressing one another by a central core hence it is called buttressed core structural system

This buttressed core is a six sided central piece

So that it is called a Hexagonal Hub

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Buttressed core cont….

This hub is surrounded by the three wings

These three wings afford the torsional resistance and the twisting of the tower

This hub encloses the elevators

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Earthquake

The earthquake was one of the most important factor that had to be challenged by the burj

Any unknown concept would collapse the whole structure

They took the Taipie101 tower for their study

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Taipei 101 A year twice China is affected with

earthquakes The Taipei 101 was raised up with 36 steel tubes They were filled with concrete for their rigidity

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Taipei 101 cont….

These columns were holding together with outrigger trusses So that these elastic bands would recover the whole movement occurred to the building

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Earthquake cont….

Providing such bands was not so practical for Burj

According to Uniform Building Code(UBC) ,Dubai was classified under a zone 2a

Moderate seismic activity The Burj would resist up to 6 in the

Richter scale Because of the massive reinforced

concrete skeleton

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Evacuation The attack against the world trade

centre at sept2001 shows the importance of evacuation in skyscrapers

How tall the skyscrapers grow makes the evacuation much harder

The Burj is different and have a perfect evacuation system

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The Burj is naturally fire resistant as the concrete backbone is already fire resistant

More than that the Burj consist of refuge rooms

These refuge rooms are made of RCC and fire proof sheets that resist the heat up to 2hrs

These refuge rooms has a special supply of air which pumps through fire resistant pipes

There are 9 refuge rooms, one in every 30 floors

Evacuation cont….

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The evacuation system The Burj evacuation system mainly

consist of 3 componentsi. A smoke detectorii. Water sprinkleriii. High power fans

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Evacuation system cont…. At first the smoke detector detects the

smoke if fired The smoke detector then activates the

water sprinkler and then the high speed fans

As the water is sprinkled the fire gets extinguished and the high power fans supplies fresh air by pushing the smoke out

So that it is perfectly fire safe

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Environment friendly

Water heating The Burj utilizes solar power 378 panels each with an area of 2.7sq.m

were installed These panels have the ability to heat

140,000 lit of water when supplied with just 7hrs of day light

This is equal to 32,000KW of energy provided

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Environment friendly cont….

Condensate recovery system Collects water condensate from the air

conditioning system And diverts it to an irrigation tank It provides about 15 million gallons of

water per year This water is used for irrigation of

landscape around the Burj Reduces water related expenses

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Environment friendly cont….

Air ventilation Air ventilation provided at the top

reduces the energy conception Air at the top of the building is cooler,

has low density and relatively humid Its ideal for ventilation Less energy is required to maintain the

comfortable condition

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Conclusion The Burj Khalifa is one of the unique tallest building

that was built by man For rising such a city in the sky several new

techniques have been used The buttressed core structural system has made a

great change in the structural system of skyscrapers

A strong buttressed core will initiate the height of the skyscrapers

The construction of the Burj Khalifa proves that height doesn't matter any civil engineering construction.

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References

Baker, W.F. and Pawlikowski, J.J. (2009)The design and construction of the World’s tallest building-Pushing technology to new heights, Structural Engineer,Dec., pp. 12-19

Lee, H.J., Kuchma, D.A., Baker, W., and Novak, L.C. (2008) Desuign and analysis of heavily loaded reinforced concrete link beams for Burj Khalifa, ACI Structural Journal, Vol. 105, No.4, July-Aug., pp.451-459.

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Thankyou