Capital Gate Building Systems

Capital Gate: Building Analysis

Abu Dhabi, United Arab Emirates

Thom Anderson

Jason Barhorst

Martin Davis III

Ashley Huffman

David Scott

Luke Stutler

Structural Systems II Capital Gate – Abu Dhabi 2 | Page

Fast Facts: Height: 525ft (160m)

Floors: 35

Building Use: Office and Hotel

Architect: RMJM Architect

Mechanical &

Electrical Engineer: RMJM

Project Manager: Mace Group

Contractor: AL Habtoor Leighton Group

Owner: ADNEC

(Abu Dhabi National Exhibitions Company)

Structural Type: Leaning Tower

Architectural Style: Deconstructivism

Cost: $231 Million (849إ.دm)


Table of Contents .......................................................................................................................................................................... 2

Fast Facts: ......................................................................................................................................................... 2

Table of Figures................................................................................................................................................. 4

Location: ............................................................................................................................................................ 5

Climate: ............................................................................................................................................................. 5

Designers: ......................................................................................................................................................... 6

Civil: ............................................................................................................................................................... 6

Architectural & Engineering: ........................................................................................................................... 6

Builder: .......................................................................................................................................................... 6

Owner: ............................................................................................................................................................... 7

Civil: .................................................................................................................................................................. 7

Site Placement: .............................................................................................................................................. 7

Soil Type: ....................................................................................................................................................... 7

Architecture: ...................................................................................................................................................... 7

Design Aspects: ............................................................................................................................................. 8

Occupancy: ................................................................................................................................................ 8

Construction Type: ..................................................................................................................................... 8

Program: ........................................................................................................................................................ 8

Height: ........................................................................................................................................................ 8

Building Envelope: ......................................................................................................................................... 9

Water/Vapor: .............................................................................................................................................. 9

Air: .............................................................................................................................................................. 9

Fire: ............................................................................................................................................................ 9

Thermal: ..................................................................................................................................................... 9

Structural: .......................................................................................................................................................... 9

Drawings: ..................................................................................................................................................... 10

Details: ......................................................................................................................................................... 10

Foundation: .................................................................................................................................................. 11

Floor Systems: ............................................................................................................................................. 11

Envelope: ..................................................................................................................................................... 12

Load Carrying System: ................................................................................................................................. 12

Gravity: ..................................................................................................................................................... 14

Mechanical: ..................................................................................................................................................... 15

Energy Requirements: ................................................................................................................................. 15

Electrical: ......................................................................................................................................................... 15


Construction: ................................................................................................................................................... 15

Budget: ........................................................................................................................................................ 15

Schedule: ..................................................................................................................................................... 16

Techniques: ................................................................................................................................................. 16

BIM: ............................................................................................................................................................. 16

Bibliography ..................................................................................................................................................... 18

Table of Figures No table of figures entries found.


Location: Abu Dhabi is the capital and the second largest city in the United Arab Emirates. Abu Dhabi lies on a T-shaped

island jutting into the Persian Gulf from the central western coast. The city proper, making up an area of

67.340 km2 (26.000 sq mi), had an estimated population of 896,751 in 2009. (Wikipedia, Capital Gate, 2010)

Climate:

(Word Travels)


Designers: This project was a design-and-build project. The architect explains that it had to be because of the types of

problems that were encountered during the project. The architect and engineer had to be extremely involved

in the project in order to solve problems. (RMJM, 2008)

Civil: Mechanical and Civil Engineering Contractors Company Limited is based in the United Arab Emirates with its

headquarters for the region located in the city of Abu Dhabi. MACE provides a vast range of services to

municipalities and oil companies encompassing all aspects of construction and maintenance. MACE prides

itself for being a Center of Excellence in the construction, operation and maintenance fields in the Middle East.

MACE provided civil services for the Capital Gate Project. (MACE)

Architectural & Engineering: RMJM is an international architectural practice with offices throughout Europe, the Middle East & Africa, Asia-

Pacific and The Americas. Their work encompasses architecture, sustainable design, urbanism, master

planning, interior design and research and development. Their culturally diverse studios are made up of almost

1000 architects, designers and creative thinkers - comprising 50 nationalities - working on projects in over 20

countries worldwide. The Capital Gate is their most recognizable project to date. (RMJM, 2008)

Builder: The Al Habtoor Leighton Group, which is the General Contractor, is one of the leading multi-disciplined

contractors in the Middle East and North Africa. It functions through its two core operating companies Al

Habtoor Engineering and Leighton and through its diverse range of complementary Associated Businesses.

The Group operates through the businesses in the UAE, Qatar, Kuwait, Saudi Arabia, Oman and Bahrain, and

is looking to expand further into the Middle East and North Africa. The Al Habtoor Leighton Group offers

clients a complete, one-stop solution to all construction, development and asset management needs. The Al

Habtoor Leighton Group employs approximately 30,000 people, making it one of the largest construction

groups in the region. (Al Haqbtoor Leighton Group, 2010)

http://www.hlg.ae/Menu/index.aspx?MenuID=14&CatID=7&mnu=Cat&div=Cat



http://www.hlg.ae/Menu/Index.aspx?MenuID=49&mnu=Pri&div=Pri


Owner: ADNEC Group is an international venue development and business management company. ADNEC Group's

portfolio currently includes the Abu Dhabi National Exhibition Centre, the Gulf's largest exhibition center;

ExCeL London, the UK capital's largest exhibition center; the Al Ain Convention Centre, a brand new

development in the historic city of Al Ain, Capital Gate, the UAE capital's iconic, gravity defying tower and a

number of hotel projects. In addition ADNEC is master developer of the Capital Centre project, the world's first

fully interconnected exhibition lifestyle destination.

ADNEC Group is developing its network both through acquisition and construction; the company's objective is

to become the world's leading venue provider to the international exhibitions, conferences and live events

industries by providing consistently high standards of venue facilities, management and client relationships and

capitalizing on the synergies which exist within a global venue network. (ADNEC, 2010)

Civil:

Site Placement: Capital Gate forms the focal point of Capital Centre, the business and residential micro city being developed by

Adnec around the thriving Abu Dhabi National Exhibition Centre. When fully complete, Capital Gate will feature

the 5-star hotel - „Hyatt at Capital Centre‟ besides playing host to some of the most exclusive office space in

the UAE capital. (Trade Arabia, 2010)

Soil Type: The construction of this building has been done on the seashore. As the sea shore contains more of sand

content, the strength for the foundation is gained by 30 meter (nearly 100feet) steel rods vertically drilled deep

into the ground. The 7 feet thick concrete laid from the ground level supports the building. (Hubpages)

Architecture:

Capital Gate was designed to be the most recognizable icon of the ADNEC/Capital Centre development.

Further, it was designed to blend seamlessly with the National Day Grandstand, breathing new life into this


historic landmark for the UAE. The eye-catching „splash‟ commencing from level 18 and sweeping across the

historic grandstand, connects the past with the new, creating a wave-like effect over the exhibition centre.

(UNP)

Design Aspects: Nothing is standard about Capital Gate. Each room is different. Each pane of glass is different and every angle

is different. It was designed to provide no symmetry so it inspires those within and outside the tower. (UNP)

The iconic tower soars 160 meters above ground and has been built with a westward incline of 18 degrees.

Capital Gate holds the Guinness Record for „World‟s Furthest Leaning Manmade Tower‟. Capital Gate contains

35 stories with floors 2 - 16 comprising office space. Floors 18 onwards will house the 189-room, exclusive

„Hyatt Capital Gate‟ hotel. Floors 1 & 17 comprise of plant rooms. (UNP)

Some other important features include:

The outdoor swimming pool on the 19th floor with a fantastic panoramic view overlooking the Sheikh

Zayed mosque, the Arabian Gulf, the Mangroves, Downtown Abu Dhabi and Saadiyat and Yas Island.

(UNP)

The cantilevered tea lounge which overhangs the outside of the tower 80m above the ground. (UNP)

The tapered internal atrium, which itself is formed by a separate structural steel diagrid over 60m in

height (from floor 19 to the roof) creates a stunning internal space that is quite unprecedented, and

which brings natural daylight deep inside the building. (UNP)

The design style type deconstructivism. (RMJM, 2008)

Occupancy:

It is a mixed use occupancy consisting of hotel and office space.

Construction Type:

It is concrete reinforced with steel.

Program: The program consists of:

Total Built-up Area: 53,100 sqm (UNP)

Total Office Area: 20,900 sqm (UNP)

Total Hotel Area: 25,050 sqm (UNP)

Height:

The building, from the ground to the top of the roof is 524.9 feet tall (160 meters). (UNP)


Building Envelope:

The tower is covered with 728 panels of glass cut to the size and shape of a diamond that due to the curvature

of the structure will be embedded in a slightly different angle. (UNP)

Water/Vapor:

The „pressure-plate‟ system that has been developed for the steel frame which holds each pane in place

guarantees the water tightness of the façade and allows thinner panes of glass to be used, thereby reducing

the weight of the glazing system,” said Tony Archibold, associate director of RMJM, the international

architectural firm that has designed Capital Gate. (Trade Arabia, 2010)

Air:

“The lean and curve of the building added considerable complexity to the glazing process; there was little

margin for error and we are pleased to have worked successfully to practically complete the glazing on Capital

Gate in ten months. A few glass panes have deliberately been left out to ensure that adequate ventilation

exists prior to the installation of the air conditioning,” said Tony Archibold, associate director of RMJM, the

international architectural firm that has designed Capital Gate. (Trade Arabia, 2010)

Fire:

During December 2008, PFP Contracting secured one of the most prestigious contracts in their history to

supply and install a passive fire protection system to the Capital Gate Tower. Much of the building diagrid

structure is a visual feature and thus requires a high quality architectural finish to the fireproofing. Because of

their depth of experience and personnel expertise, PFP Contracting qualified to install the steel fireproofing.

(PFP Contracting)

Thermal:

The glass used on the tower‟s facade is energy-efficient, low „e‟ category glass (Cardinal 240) containing 2

layers of silver inner coating allowing a high degree of natural light to permeate the building never before used

in the UAE. It‟s designed to keep the inside of the building cool and eliminate glare, while maintaining the

transparency of the facade - an important design consideration. (Trade Arabia, 2010)

Structural:


Drawings: (Tekla

Project3,

2010)

Details:


(Tekla

Project3, 2010)

Foundation: Due to the soil conditions and the building itself the foundation system used was a deep foundation. The

building sits atop a dense mesh of reinforcing steel and concrete that connects a total of 490 piles (Capital

Gate, 2010). To help counteract the large overturning moment, which is caused by the buildings lean, the piles

were two different sizes. Of the total 490 piles, 287 were 1m (40in) in diameter, and 20-30 meters (65-100 feet)

deep, the remaining 193 piles had a diameter of 600mm (24 inches) with a depth of 20m (65 feet). Unlike most

buildings, whose piles are in compression, the piles for Capital Gate are in tension. This was done to help

resist the upward forces that would tend to pull the pile out of the ground. The building, however, cannot sit

directly on top of the piles. All 490 piles were capped together using a densely reinforced concrete mat footing

of nearly 2 meters (7 feet) thick (Roberts, Lean on Me, 2010).

Floor Systems: The floors are constructed using a composite floor system, spanning from the main core, to the internal diagrid,

and between the internal and external diagrids. The floor beams are connected to the concrete core via

embedment plates which are cast directly into the core wall when the concrete is poured. All the floors have

the same relative size as the floors rise. The first ten floors are stacked vertically directly on top of one another.

The floor plates, on level 10 through 27, stagger over each other, between 800 (32inches) to 1400mm

(55inches) and then back to 900mm (35 inches) in line with the lean of the building‟s face. The remaining

floors, between levels 27 and 34, shift between 900mm (35inches) and 300mm (12inches) (Roberts, Lean on

Me, 2010).


(Record)

Envelope: The building envelope consisted of a combination of glass and steel. The system consisted of a large

prefabricated 8m (26.25ft) tall diamond-shaped panel, which are installed and connected to the diagrid. Over

700 panels were used to enclose the structure, each panel included 18 different panes of glass, covering

roughly 23000m2 (247570ft2). All the panels are shipped to the site assembled and raised into it precise

location, since each panel is slightly different. To add to the uniqueness of the building each panel had to be

installed correctly to allow for some movement as the building corrects from the core‟s pre-camber (Reina,

2009).

(Record)

Load Carrying System: The structural system consists of two diagrids, an internal and an external diagrid, and a center concrete core.

A diagrid is a new system used in the construction of large buidlings which creates a skeleton composed of


triangular structures and diagonal support beams, using less steel than a typical steel frame building.

Additionally it eliminates the need for large corner columns, allowing more flexibility in the shape of the

building‟s form as in the case with Capital gate (Diagrid, 2010). This diagrid system was chosen because of the

unique architectural form of the building, the constantly changing position of the core in relation to the varying

floor plates, and the desire to have large clear internal floor spaces. The exterior diagrid carries the weight of

all the floors, while the internal diagrid supports the weight of the floors and transfers it to the center concrete

core (Roberts, Lean on Me, 2010). The diagrid system used for the building consists of 722 elements and

approximately 8,500 structural steel beams, with each element weighing nearly 15 tons and has a painted

finish (The Mace Group, 2009).

(Record)

(Record)


Gravity:

Gravity, seismic and wind forces along with the dead load of the building play a large role in the in the design

and structure of the building. This building is different because its signature lean, which sets the building apart

from the other buildings, adds a much larger load to the gravity and dead load of the building, and creates a

large overturning moment. The center concrete core had to be specially designed to account for the immense

forces created by the building‟s lean. The core, which contains 15,000m3 (19,619yd2) of concrete reinforced

with 10,000 tons of steel, uses vertical post-tensioning and was constructed with a vertical pre-camber. This

pre-camber means that the core was constructed with a slight opposite lean, as each floor is installed, the

weight of the floors and diagrid system pull the core and slowly straightening it out. As the core is straightened

it is post tensioned, thus making the core and structure incredibly strong (Crowcroft, 2010).

(Record)

(Record)


Mechanical: The hotel space, in particular, will feature a double facade. This will create a thermal cushion in the intervening

space which should significantly reduce building energy demands. There are also energy recovery measures

integral within the building‟s MEP systems. (Roberts, Lean on me, 2010)

Energy Requirements: The double-glazed facade is used to achieve greater energy efficiency. Waste air is pre-cooled in between the

inner and outer facade thereby reducing the energy consumption of the building by recycling the used air.

The stainless steel „splash‟ is a shading device that eliminates over 30 percent of the sun‟s heat before it ever

reaches the building, thereby saving on the need for cooling within the building. The splash twists around the

building towards the south to shield Capital Gate as much as possible from direct sunlight (UNP)

Electrical: As far as our research has found, there are no energy saving or special features directly located on the

building. However, the Aloft building, another hotel located in the compound, is tied into a total of 560 solar

panels installed on the roof of ADNEC Car Park A, covering an area of 25,000sf (2,300sm), that provides 90%

of the hot water supply. This saves an estimated 870 mega watt hours of electricity per year and supplies hot

water to the kitchens, hotel rooms and pool. (Wikipedia, Abu Dhabi National Exhibitions Company, 2010)

Construction:

Budget: What‟s more, the budget has escalated by 25% and sorely tested the team responsible for delivering the

building. It was meant to have been finished in time for last November‟s Abu Dhabi Grand Prix but now won‟t

be ready until October 2010.

This is all fine in theory but someone had to realise it. This was the job of contractor Al Habtoor Engineering,

which also had to cope with the fast-track program typical of the region. The original two-year build-time started

in August 2007 with the design developed as work progressed. Luckily Al Habtoor Engineering wasn‟t on a

fixed-price deal. The FIDEC contract was used which relies on bills of quantities with rates that are re-

measured as the building is constructed. “If it had been design and build it would have bust the company,”

observes site manager Craig Rooney.

The project got off to an inauspicious start. The design included an 84m-long basement extending in the

opposite direction to the lean. This had tension piles at the far end to stop the whole basement being ripped

out of the ground by the overturning forces generated by the tower. Unfortunately the main sewer for Abu

Dhabi was discovered underneath the proposed basement. As the sewer was pressurized, the ground couldn‟t

be dewatered near it because there was a risk the pipe could burst. The solution was to shorten the basement

by 6m and reduce the entrance canopy, but agreeing and implementing it added six months to the project.


Schedule: It was delayed by 5.5 months because of unexpected excavations and piling restrictions due to two nearby

main sewage lines. The project so far has used 6.5 million Man hours and at the peak of construction there

were more than 1,200 workers on site.

Final Timeline:

September 2007 Enabling works commence

April 2008 Core wall construction starts

February 2009 Façade work commences

May 2009 Capital Gate reaches 100m in height

October 2009 Attains final height of 160m

December 2009 Completion of exterior core structure

February 2010 Interior fit-out commences

March 2010 Work on link bridge to Abu Dhabi National Exhibition Centre begins

April 2010 Work on of atrium roof begins

End 2010 Expected completion of construction

Techniques: Incredibly the pre-cambering and post-tensioning of the core were variations in the contract; originally it was

going to be straight. The core was built so it leaned from the vertical by a theoretical 350mm at the top. In

practice the steel diagrid and cladding were added as the core was constructed, progressively straightening

out the building. Rooney likens it to shooting at a moving target. “Every time you added a section of structural

steel, it had an effect; every time you added a cladding panel, it had an effect,” he says. “People couldn‟t get

their heads around it.”

The core was built in 4m high lifts with each section staggered 20mm to create the pre-camber. Every four lifts,

36 steel tendons were inserted into the ductwork in the concrete and post-tensioned.

In order to get the custom glazing panels to the site, a custom fabricated truck bed had to be constructed.

BIM: Complexity in modeling the diagrid members was well managed with the features of Tekla Structures. The

Tekla attributes helped in all fronts for a smooth construction of the structure. Concerning design, members

were oriented with minimal offset by adopting the method of bisection of bisecting planes. These offset values

were taken from the 3D model and used in the design of cruciform nodes. Available length of weld was taken

from the model to do the weld design of cruciform nodes. Beams connected to the nodes were moved in the

3D model to avoid member clashing which resulted in eccentric connections. The eccentricity was measured

from the model and used in the connection design. From the preliminary model developed at the initial stage of

the project actual cut-to-length of the members was taken to procure the material. This helped in reducing

material wastage. Quantity of bolts, shear studs and paint was obtained from the Tekla Structures reports.

Assembly lists derived from the Tekla model were converted into worksheets. Other departmental activities,

like fabrication, painting and erection, were planned and monitored using these worksheets. The NC files

exported from the model facilitated faster and accurate fabrication. Temporary jigs were made with the help of

the coordinates of individual assemblies that were taken from the model. Fit up of the individual parts of the

nodes was done with the 3D coordinates taken from the model. Location of center of gravity and weight of

individual assembly were taken from the reports. These were used to work out the lifting method statement and

in the design of erection engineering. Bolt report based on the assembly mark helped the rigging team to have

control over bolt usage. 3D global coordinates taken from the Tekla model were utilized for erecting the diagrid

assemblies at their exact position. The 3D model was also given to the cladding team to work out the design of


the cladding system. The model was used to coordinate with the architectural profile model to nullify the

interface issues. Thus the model generated in Tekla Structures had played a vital role in the successful

completion of the works in a safe and faster way. (Tekla Project3, 2010)


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Capital Gate Building Systems