3 r d Q u a r t e r 2 0 0 6

rticleA

77

In recent years, all over the world,the construction industry isemerging very rapidly both in

engineering and technology, andcontributing significantly to economicdevelopment. In the later part of thepast century, there has been extensiveusage of steel in the constructionindustry and steel explored much morepossibilities to substitute otherconventional materials.

With today’s structural steel framing,grace, art and function can cometogether in almost limitless ways; itoffers new solutions and opportunities,allowing architects to stretch theirimagination and actually create some ofthe most challenging structures theyhave designed in their minds.

Structural steel has entered a new era.Today it provides not only strength tobuildings but also beauty. Steel is notonly being used to provide a stableframework for a structure but in manycases is also chosen for its aestheticappearance.

Eversendai have had the good fortuneto be involved in steel structureprojects of diverse types one of whichwas The Burj Al Arab. It will demonstratethe versatility of steel for variousapplications and also illustrate thevarious complexities:-

Designed to resemble a billowing sail,one of the most fascinating, majestic,wonder structures in the world, theBurj Al Arab soars to a height of 321m,

dominating the Dubai coastline. Thisall-suite hotel reflects the finest thatthe world has to offer. An architecturalmarvel, it is an engineering excellencefor the 15th tallest building in theworld.

It is the world’s tallest hotel structure.This project has become Eversendai’ssignature project and it has paved theway for Eversendai’s entry into theMiddle East’s booming constructionmarket as a specialist structural steel

contractor. Now Eversendai isdominating their presence in theMiddle East.

The Burj Al Arab means “Tower of theArabs” is situated at Dubai, UnitedArab Emirates, designed by MrThomas Wills Wright. It stands in thesea, 280m away from the beach in thePersian Gulf on a man made islandconnected to the main land by aprivate curving bridge. It has access byLand, Sea and Air.

Burj Al-Arab, UAEStructural Steel Construction ForA Mega ProjectBy Dato’ A K Nathan, Managing Director, Shin Eversendai Sdn Bhd

Burj Al Arab

3 r d Q u a r t e r 2 0 0 6

rticleA

78

It is one of the most fascinating,complex and challenging project everundertaken by Eversendai.

The structure is a standing example forthe quote “Architect’s Dream, Engineer’sNight Mare”.

Steel is the best-opted material for thisbuilding due to its flexibility andconstructability.

The Burj Al Arab building is made of 28storeys of split levels (56 storey) with100,000 m2 floor area, 60000 m3 ofconcrete, 9,000 ton of reinforcing steel,12,000 ton of structural steelworks,80000 m2 of cladding, 10000 m2 of teflon- coated fiber glass cloth and sits on 250piles of 1.5m in size, 45m under the sea,the piles rely on friction as there is onlypiles embedded in sand to hold thebuilding up.

Construction of the Burj Al Arab hotelbegan in1994, and its doors wereopened to guests in December,1999.The top is the mast and below it is thehelipad, and extending from the otherside of the hotel, over the ocean, is arestaurant supported by a cantileverstructure. A remarkable element of itsarchitecture is the outer beachwardsteel wall of the atrium, which is covered

with a woven, Teflon-coated fiber glasscloth. The Burj al-Arab features thetallest atrium lobby in the worldstanding at 180m.

This Burj Al Arab building is a hybrid Vshape structure constructed in concreteup to 209 m and blended with structuralsteel creating an impressiveengineering master piece. This V-shaped frame wraps around the Vreinforced concrete tower containingthe hotel rooms and lobbies. The twostructures connect along a shored,reinforced concrete spine at the base ofthe V, and at two points along thecurving atrium wall.

Ninety percent of the steel structuresconstructed were outside the buildingand was potentially dangerous to erect.Three self-climbing tower cranes with amaximum lift capacity of 64 tons at 8.0meters radius were used. Some of theembedment weighed as high as 60tons.

About 100 tons of electrodes wereburned and the welding defect ratiowas less then 1%.

The Burj Al Arab does not have ordinaryrooms; rather it is divided into 202duplex suites with split levels. The

smallest suite occupies an area of 169 sqm, and the largest one covers 780 sq m.It is one of the most expensive hotels inthe world to stay in. The cost of stayingin a suite begins at US$1,000 per nightand increases to over US$15,000 pernight; the Royal Suite is the mostexpensive, at US$28,000 per night.

We are proud to say that this projectwas the major break through forEversendai Engineering in Middle Eastregion. The Project was been awardedto Eversendai purely based on itsconstruction methodology, capabilityand reliability. Eversendai scopeincludes the site assembly, alignment,welding and erection of structural steelworks.

Total Steel works are phased intoExoskeleton Rear leg, Horizontals,Diagonals, Rear Brace Frame, Helipad,Sky Restaurant, Atrium and the Mast :-

Exoskeleton Rear leg Erection

The exoskeleton is made up of two legson both sides of the building startingfrom the ground level to 273 metersand connected to the front legs startingfrom 208m. The total weight of thestructure is about 2,800 tons. Thestructure was made of two build up Hsections of 1.8 metre wide by 4.5 metredeep plate girders (inner and outer legs)connected by a lattice braced membersand segmented to 40 ton capacity 12min length to create the gentle curve inconcurrence with the building edgedeveloping the shape of a sail.

The assembled segment were lifted anderected in position using the towercranes from ground floor to top, oneover another using specially designedlifting lugs with 20 ton chain hoists inthe pre-determined lifting location tolift the segment in required angle.

After each segment were erected,temporary struts were introduced to tieback the rear leg to the core wall toHybrid V shape structure

3 r d Q u a r t e r 2 0 0 6

rticleA

79

maintain alignment until theExoskeleton grows to the next point ofpermanent connection and thenconnected permanently with the LinkStud weighing about 10 tons to theconcrete core. There were three Linkstuds on each side of the building,fixing at three points for the entirelength of 273 metre Exoskeleton to thediagonal brace and horizontal bracepoint and continued erection of thesegment only after the erection ofdiagonals and horizontals and finallyconnecting to the front legs startingfrom 208m.

All exoskeleton are lifted inpredetermined angles adjusted bychain blocks, hooked on to the craneand lifted in segments. All the joints areof full penetration welding andinspected by ultrasonic test.

Platforms were fitted at each joint forwelding and other related works

Alignment was carried out usingelectronic digital total station located atthree different fixed locations, allsurveying are done very early in themorning to get a more accurate reading,keeping in mind the movement of thestructure due to thermal effects whichgenerally develops deflection.

Rear Brace Frame

The two cores on the rear side of thebuilding are 40m apart and connectedby huge cross bracings of fabricatedbox sections called the rear braces.

The box sections were brought into thesite in transportable segments. Thecross sections of the boxes are 2.2m by1.4m and made of from 25mm to 40mm thick plates. The box sections areassembled and welded at the groundlevel by the side the building.

This brace ties both the cores togetherto give stability to the structure. Thetotal tonnage of this part alone is 1600tons. The shape of the Rear Brace issimilar to “X “are erected in segments.All the joints are of full penetrationwelding.

These rear braces form as X of threeportions for the whole building. Thelength of one brace was around 60m inone direction from one side of thebottom embedment to the upperembedment of the other side of thecore, it was spliced into three pieces.The first piece was about 24m andweighs about 50 tons and was lifted bytwo tower cranes as a tandem lift anderected between core embedmentfrom one side and the another endrested on the temporary lattice girdertrusses running between cores tosupport the rear brace segmentalerection. Once these two 24mts braceswere erected then the X of 12m lengthof 52 tons was erected by two towercranes as tandem lift supported by thesecond layer of temporary latticegirder truss, which was erectedbetween cores, the whole rear brace isin inclined towards the inside of thebuilding. After all welding, touch upinspections been carried out, all thetemporary platforms, scaffolds and thethree lattice girder trusses wereremoved from its position and re –erected to the upper portion of therear braces location to continue the

same process of erection to completethe three portions of X rear braces inthe building.

Diagonals

The diagonals are of huge tubulartriangular truss geometry having themaximum cross section at the middlelength and merged as one member atthe ends. The Diagonal vary from 76mto 90m in length and weigh 160 to 180ton. The Diagonal connects with a300mm diameter pin connection tothe core-wall and the Rear-legstructure. There are six diagonalserected at different levels on both sideof the building.

These diagonals are transported as asingle fabricated piece from thefabrication shop 15 km away by specialself propelled long trailers.

Strand jacks supported by Cat headswere connected to the building toexecute the lifting of the Diagonalsand Horizontals. Utmost care wastaken to ensure that the measurementlength between the core and theexoskeleton rear leg so that thediagonals with pin connection can beconnected with ease.

Framework

Front view of Burj Al Arab

3 r d Q u a r t e r 2 0 0 6

rticleA

80

Horizontals

The horizontal weighting about 200 tonsconnects the core wall to theexoskeleton rear leg. This structure wasassembled in one piece in the assemblyyard near the project side. TheHorizontals were transported by longspecial self-propelled trailers to theerection site.

They had to be erected between twofixed points so utmost care was taken tomeasure the length between the coreand the exoskeleton rear leg.

Horizontal were erected by strandjacking method similar to Diagonals,using the same cat heads platforms.

Once the horizontal reached itsdetermined elevation, then it was slidetowards the building and placed to itsposition connected with bolts andwelding.

The strand jacks and the cat headplatforms were removed from itsposition and kept ready for the next cycleof operation. Once cat heads and strandswere removed then the Exoskeletontypical erection sequence was carriedout up to its level to the next diagonaland horizontal fixing point and thenstopped to continue diagonal andhorizontal strand jacking operation.

Helipad Structure

This structure is at 212m level at the rearside of the building, weights about 330tons made up of steel trusses and 20mmthick plates. Two props of 1m diametercircular steel pipes, forming an invertedV shape, tapered at 30º to the vertical andtied back to the center core by a 40mlong spine truss weighing 120 tons,support the total Helipad structure.

Sky Restaurant Structure

The 350 ton structural steel skyRestaurant was one of the most complex

and potentially dangerous structuresto erect. The box girders cantileverout for about 30m from the main corewall of the building connected toabout 200 tons of embedment. Therestaurant is having a floor size of 70mx 25m. The total structure is built upon eight cantilevered box sectionsand two end trusses at 200m abovethe ground level. The beauty of therestaurant is that it over looks the sea.One of the highlights is, two 30m longgirders had to be erected at 200mlevel but the crane did not have thelifting capacity so we had to split thegirders into halves and joint up in theair with full penetration welding, itwas a real challenge and Eversendaitook it up and performed beyondeveryone’s expectation in a recordduration of 40 days.

Mast

The mast is about 104mts long, only54m was braced in betweenExoskeleton support legs starting from208m level on the core wall and thebalance cantilevers vertically 50m wayabove the Exoskeleton.

The overall mast was erected insegments of average 30 ton weightmatching the tower crane capacity. The

mast is in oval shape of 2.5m x 5m at thebottom and gradually decreases to 2.5x 2m at top. All the segments werebolted inside by ring plate flangeconnections. All the segments hadinside arrangements of permanentladders and interval platforms tofacilitate access and maintenance.

The first segment of the mast waserected after the Exoskeleton waserected on the trusses which runbetween two Exoskeleton legs inhorizontal plane.

There were manholes at periodicintervals, through that workers hadaccess to go and come out from themast to the nearby Exoskeletontemporary scaffolding arrangement.Temporary Safety exhaust fans wereintroduced inside the mast to have aircirculation to workers.

Before the mast erections coming toend with the use of the tower crane, theother two cranes were dismantledexcept the crane near to mast.

Finally the third crane was dismantledby derrick crane. After completedismantling of tower crane, derrick cranewas dismantled manually and loweredfrom the roof top by winches. MBJ