SEMINAR ON :

Burj KhalifaConcept, Design &

Construction

PRESENTED BY KAILASH JANGIDROLL NO- 09149

CONTENTS

INTRODUCTIONSTRUCTURAL ANALYSIS WIND EFFECTSOIL INVESTIGATIONFOUNDATIONPLANNING OF CONCRETE

WORKCLADDING AND LIFTS

Introduction• Burj Khalifa (formally Dubai) is the new

tallest tower in the world.• Construction began on 21 September

2004 & completed on 1 October 2009. • The building was officially opened on 4

January 2010• Height of the Tower is 828m .• It’s Owner is EMAAR Properties with total

investments of US$ 1.5 billion.• The tower is designed by Skidmore,

Owings and Merrill • Adrian smith was chief architect.

World’s Tallest Building• Highest outdoor observation deck in the

world (124th floor) at 452 m • World's highest and fastest elevators at

speed of 64 km/h • Highest vertical concrete pumping (for a

building): 606 m • World's highest installation of an aluminum

and glass facade, at a height of 512 m • World's highest New Year fireworks display

Main Structure & DesignThe tower superstructure of Burj Dubai is designed

as an all reinforced concrete building with high performance concrete from the foundation level to level 156, and is topped with a structural steel braced frame from level 156 to the pinnacle.

Designers purposely shaped the structural concrete Burj Khalifa – “Y” shaped in plan – to reduce the wind forces on the tower, as well as to keep the structure simple and foster constructability.

The structural system can be described as a “buttressed” core. Each wing, with its own high performance concrete corridor walls and perimeter columns, buttresses the others via a six-sided central core, or hexagonal hub

Structural Analysis & Design

The top section of the Tower consists of a structural steel spire utilizing a diagonally braced lateral system.

The structural steel spire was designed for gravity, wind, seismic and fatigue in accordance with the requirements of Load and Resistance Factor Design Specification for Structural Steel Buildings . The exterior exposed steel is protected with a flame applied aluminum finish.

Main Structure & Design Tower that is extremely stiff

laterally and torsionally similar to a closed tube.

Each tier of the building sets back in a spiral stepping pattern up the building. The setbacks are organized with the tower’s grid, such that the building stepping is accomplished by aligning columns above with walls below to provide a smooth load path.

The advantage of the stepping and shaping is to “confuse the wind”. The wind vortices never get organized because at each new tier the wind encounters a different building shape.

Structural Analysis & DesignThe center hexagonal walls are

buttressed by the wing walls and hammer head walls which behave as the webs and flanges of a beam to resist the wind shears and moments.

Structural Analysis & Design Concrete Dimensions

The core walls vary in thickness from 1300mm to 500mm. The core walls are typically linked through a series of 800mm to 1100mm deep reinforced concrete or composite link beams at every level.

The residential and hotel floor framing system of the Tower consists of 200mm to 300mm two-way reinforced concrete flat plate slabs spanning approximately 9 meters between the exterior columns and the interior core wall.

Types of windWinds that are of interest in the

design of buildings can be classified into three major types◦Prevailing Winds (Trade winds)◦seasonal winds◦local winds

Types of windThe characteristics of the

prevailing and seasonal winds are analytically studied together, whereas those of local winds are studied separately.

The variations in the speed of prevailing and seasonal winds are referred to as fluctuations in mean velocity. The variations in the local winds are referred to as gusts.

Wind behavior

WIND CLIMATE STUDIESAn important question when designing a tower of

over 600 m height is the nature of the wind velocity profile and wind turbulence in the upper levels.

It is a large extrapolation to go from ground-based data at the 10 m height to heights of over 600 m using standard assumptions

Therefore for Burj Dubai more direct measurements of upper level winds were sought. The closest station with balloon records was Abu Dhabi, where about 16 years of data were available taken on average about twice per day.

Foundations

Soil Investigation & Ground Water• The groundwater in which the Burj Dubai

substructure is constructed is particularly severe.

• The chloride and sulfate concentrations found in the groundwater are even higher than the concentrations in sea water.

• Measures implemented include specialized waterproofing systems:1. Increased concrete cover2. Addition of corrosion inhibitors to the

concrete mix3. Stringent crack control design criteria 4. Impressed current cathodic protection

system utilizing titanium mesh .5. A controlled permeability formwork .

Ground Water & Concrete Mix

• A specially designed concrete mix was formulated to resist attack from the ground water.

• The concrete mix for the piles was a 60 MPa mix based on a triple blend with 25% fly ash, 7% silica fume, and a water to cement ratio of 0.32.

• The concrete was also designed as a fully self consolidating concrete, A robust cathodic protection system for both the bored piles and the raft foundation

PilesThe Tower raft is supported by 194 boredcast-

in-place piles1.5m diameter and 47.45m long with the

tower raft founded at -7.55mThe C60 (cube strength) SCC concrete was

placed by the tremie method utilizing polymer slurry. When the rebar cage was placed in the piles, special attention was paid to orient the rebar cage such that the raft bottom rebar could be threaded through the numerous pile rebar cages without interruption, which greatly simplified the raft construction.

The Tower raft is supported by 194 bored cast-in-place piles. The piles are 1.5 meter in diameter and approximately 43 meters long with a design capacity of 3,000 ton each.

The Tower pile load test supported over 6,000 ton.

Settlement It was determined the maximum

long-term settlement over time would be about a maximum of 80mm .

This settlement would be a gradual curvature of the top of grade over the entire large site. When the construction was at Level 135, the average foundation settlement was 30mm

Construction Achieve a three (3) day-cycle for structural

works.Develop optimum transportation systems

with large capacity high speed equipment.Utilize optimum formwork system to

accommodate various building shapes along the building height.

Develop organized logistic plans throughout the construction period.

Apply all high-rise construction technologies available at the time of construction.

Planning for the concrete work• Prior to the construction of the tower,

extensive concrete testing and quality control programs were put in place to ensure that all concrete works are done in agreement with all parties involved.

• Tests are needed to confirm the construction sequence of these large elements and to develop curing plans that are appropriate for the project, considering major daily and seasonal temperature fluctuations

Testing Regimes for Concrete• Trial mix designs for all concrete types needed for the

project.• Mechanical properties, including compressive strength,

modulus of elasticity, and split tensile strength.• Durability tests which included initial surface

absorption test and 30 minute absorption test.• Creep and shrinkage test program for all concrete mix

design.• Water penetration tests and rapid chloride permeability

test.• Shrinkage test program for all concrete mix designs.• Pump simulation test for all concrete mix design grades

up to at least 600 meters.• Heat of hydration analysis and tests.

Technologies used to achieve 3-day cycles

• Auto Climbing formwork system (ACS)• Rebar pre-fabrication• High performance concrete suitable for

providing high strength, high durability requirement, high modulus, and pumping

• Advanced concrete pumping technology• Simple drop head formwork system that

can be dismantled and assembled quickly with minimum labor requirements

• Column/Wall proceeding method, part of ACS formwork system

Sequence of Construction and ACSThe ACS form work is divided into four sections consisting of the center core wall that is followed by the wing wall construction along each of the three tower wings.

Rebar Pre-fabrication • Most of the reinforcing

bars for the core walls, wing walls, and the nose columns were prefabricated at the ground level.

• This rebar fabrication and pre-assembly method resulted in man quality control advantages and reduced the number of workers going up and down the tower.

• The rebar was assembled in double story modules to speed up the vertical element construction time.

Concrete Pumping Level Height Pouring Method Remarks

Ground ~ L145 531 m Direct PumpingTarget Height (RC Structure)

L146 ~ L160M 624 m Re-pumpingSecondary Pump on

L124 (East wing 442m)

L160M ~ Spire1 681.7 m Hopper by T/C From Ground Level

Level Pressure OutputEngin

eRemarks

Pump#1~#3

185 / 320 bar

71 / 36 m3/hr

470 kw

2 nos. of Main1 no. of Stand by

Pump#4220 / 260 bar

110 m3/hr200 kw

SecondaryPumping

Concrete Pump

Concrete Pumping

Concrete Pumping

EvacuationBurj Dubai has built in fire protection as its concrete back bone is naturally fire resistantBut how will people go out in an emergency? • The burj dubai contains 9 special rooms

build throw layers of reinforced concrete and fire proof sheeting

• The walls of these rooms will stand the heat of a fire for 2 hours

• Each room has special supply of air pumped throw fire resistant pipes, sealed fire proofed doors stop smoke from leaking in

Evacuation

How they prevent the smoke from blocking the access route to the rooms?

• Early warning system:• Fire activate a smoke detector• Heat sensor• Water sprinklers• Net work of high power fans kick in• Fans force new clean cool air throw fire

resistant ducts into the building• The fresh air pushes the smoke out of the

stair way keeping the evacuation route clear.

Cladding • 30000 glass panels of high quality European

glass enough to cover 17 football fields

• The glass is thicker at the top to resist the high wind

• Its designed to let the maximum light in and to keep heat out

Sun screen (inside face) is useless against infrared

from the hot desert sun so the inner planis coated with

a thin layer of silver that keeps the heat rays out.

Outside coat reflects the daily solar heat comes direct from the

sun.

The metal coating deflects U.V. Radiation that will otherwise heat

up the building

Façade Maintenance • The tower's primary window washing and facade

maintenance system consists of three permanently-installed, track-mounted, telescopic building maintenance machines located in internal "garage" positions on uppermost levels.

• it will take 36 workers three to four months to clean the entire exterior facade

Elevators• With an ‘intelligent

elevator installation’ mechanism, builders of Burj Dubai ensure a speedy journey from the ground to the 160th floor.

• 57 elevators and eight escalators to streamline the needs of the residents and visitors to commute within the tower. These elevators mark the highest installation in any building and have been developed by Otis.

Elevators

• The main service elevator that is positioned in the central core of Burj Dubai has the world’s highest elevator rise at 504 metres

• It moves at a speed of 9 metres per second and also has the world’s longest travelling distance for an elevator. The lift to the spire has the world’s highest landing at 636.9 meters.

Elevators• Elevators are placed into

different zones. Each elevator zone serves different audiences, maximizing the efficiency and saving time.

• The sky lobby is an intermediate floor where residents, guests, office staff will change from an express elevator to a local elevator which stops at each floor within a certain segment of the building. The sky lobbies are located on level 43, 76 and 123 and will include a lounge area.

REFRENCES:http://cantilever.files.wordpress.com/

2008/06/som_tallest.pdf.http://www.ctbuh.org/Portals/0/

Repository/P2_Baker.1ce602c3-272d-4b2a-acc3

http://www.structuremag.org/archives/2006/Nov-2006/F-Burj- Dubai-Tower-Irwin-etal.

Documentary Movie – National Geographic Channel - Burj Dubai

Documentary Movie – Discovery Channel - Mega builders Extreme Elevation Burj Dubai

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