Chueng Kong Centre Construction

8/2/2019 Chueng Kong Centre Construction

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Cheung Kong CenterConstruction of by Raymond Wong Wai Man

The Cheung Kong Center exhibits a lot of special features both in theconstruction of the substructure and the superstructure. The substructureinvolved the construction of a 1.2 m thick reinforced concrete diaphragm wallalong the site perimeter; excavation to form a 37m-diameter shaft pit supportedon the side by diaphragm wall panels for the construction of the buildingcore; excavation and construction of eight 6 m-diameter caissons using hand-

dug method as foundations for the super-columns and 21 smaller caissonsof 1.5m diameter for other columns that support the new basement.

The building core of the superstructure is constructed using a self-climbingformwork system known as the jump form. The external steel frame togetherwith the floor membrane is of composite nature with circular steel sectioninfill with RC (concrete filled tube) as the columns, and steel joists with RCtopping as the floor slab. The structural frame is supported on the lower levelby 8 super-columns fabricated from heavy steel sections. A transfer trussframe and 3 sets of out-rigger frame linking onto a belt-truss system are usedto stabilize the building and to improve structural performance in the taking

up of wind load. The exterior of the building is to be finished using a stainlesssteel curtain wall system.This article aims to provide an overall illustration that highlights the above-

mentioned features start from the commencing of the substructure up to thecompletion of the building.

Redevelopment of the Hilton

Hotel site and nearby propertiesin Central District, Hong Kong

The previous Hilton Hotel building before it was demolishedin 1995 for redevelopment as the new Cheung Kong Center


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Introduction

The project situated in a 9,650 sq msite, which comprised the previousHilton Hotel, the BeaconsfieldHouse and Garden Road Car Parkin Central. The new building is a 62-storey composite structure, with a 22m x 27 m reinforced concrete inner

core encased in a 47 m x 47 mexternal steel frame, together witha 6-level basement that constructedover the 2-level old basement ofHilton Hotel.

The site comprised of 3 separateportions and handed over to thecontractors at 3 distinctive stages.The former Hilton Hotel portion inwhich the main building towersituated, was handed to the

demolition contractor in mid 1995and further to one single contractorfor the foundation and the generalbu i ld ing works in May andDecember 1996 respectively. TheBeaconsfield House portion, inwhich some open spaces and apublic toilet would be built, washanded over in early 1997. Whilethe Garden Road Car Park was

handed over at a much later stagein December 1998, by the time thenew 6-level basement of CheungKong Center, which used as animmediate substitute to the GardenRoad Car Park, was eventuallycompleted.

With these special constraintsand the usual rapid time requirementurging for earliest completion of

building by the developer, a very fasttrack construction schedule wasthus unavoidable. Within a contractperiod of about 105 weeks, thecontractor was required to completeand hand over the building in 3stages. The construction of thebasement and the main structure up

to the 25th level including all thebasic building services should becompleted within the first 45 weeks.In the following 25 weeks, the restof the composite structure should allbe completed. The remaining timewould be concentrated on theoverall finishes of the building.

Demolition and foundation

The demolition of the old Hilton Hotel

started from July 1995 and thecontract lasted for about 9 months.Method employed to demolish the28-storey hotel building was rathertradit ional. Four excavatingmachine equipped with pneumaticbreaker were used fo r thedemolition. Several dumping shaftswere formed on the floor slabs fordeposal of building debris.

W h e n t h e b u i l d i n g w a sdemolished up to ground level,raking shore using universal steelbeam was erected to support the 2-level basement of the old HiltonHotel before further demolitionproceeded. After the shoringerected, demolition to the upperbasement continued. The lowerb a s e m e n t w a s r e m a i n i n g

External viewso f C h e u n g

Kong Centerfrom var iouslocations


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untouched. It was filled afterwardpartly with debris obtained from thedemolition and partly by importedf i l l ing mater ia ls to minimizedisturbance to the basementstructure. When the works werecompleted, the site was formed andleveled up to the road level.

The works that followed were theconstruction of the diaphragm wallsand the bored foundation for the newbuilding.

All the diaphragm walls employedin the project were of 1.2 m thickreinforced concrete. The perimeterwalls were permanent structure,which helped to support andstabilize the ground during theconstruction of the new basement,

as well as to act as the permanentbasement wall. There was a 37m-diameter shaft pit formed in themiddle of the site for the constructionof the core wall for the future tower.This shaft was lined on the sides bydiaphragm wall panels, which actedas a temporary structure for the sakeof forming the shaft.

Large diameter bored piles were

used as foundation for the newbuilding. The bored piles werebasically in two standard sizes.Eight of the piles were 6m indiameter and dug manually forsupporting the super-columns. 20piles were of 1.5m in diameter anddug mechanically using gribs andprotected by steel casing duringexcavation. These piles were for the

support of the columns for the 6-level basement structure.

Forming a 37m-diametershaft pit and the constructionof the core wallBefore the carrying out of thebasement construction using a top-

down method, the first major workbelow ground was to construct thecentral core of the main buildingtower, the foundation of whichrested on the bedrock about -28mfrom existing ground level.

Instead of constructing the centralcore in a top-down manner, the corewas built bottom up. This is beingmade possible by the forming of apit large enough to house the core

structure and its foundation. A pitwas thus formed with the sidessupported by panels of 1.2m-thickRC diaphragm wall. When the pitwas excavated down to the requiredformation level, a 5m-deep RC raftwas constructed as foundation forthe core.

On top of the raft foundation, thecore wall on the lowest basement

level was constructed usingtraditional timber formwork. Basingon the completed wall section, a jump-form was then erected toconstruct the core wall, whichcomprised of the shutter panels forthe casting of the entire core wallsection, a lifting screw jack system,as well as the work platform andscaffold that attached onto the form


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system for access to the shutterpanels for works. This jump-formsystem would be used starting fromthe second lowest basement until itreached the roof on the 62nd level.

Construction of the basementImmediate after the completion of

the bored pile, steel column waserected on top of each pile at itsformation level, which would beused as support to the basementslabs during the constructionp r ocess us ing a t op - dow nsequence.

In order to allow the core wall andthe structural frame to proceed to asafe separating distance, the firstslab of the basement (i.e. the ground

floor slab) was cast after the corewall had been completed up to the9th level, and with the transfer trusson the 2nd and 3rd level basicallyerected.

Further excavation downwardwas relatively smooth. With thetemporary diaphragm wall thatformed the 37m-diameter shaftgradually being demolished, the

basement slab bound by the 8super-columns was cast andconnected to the core wall structureas soon as a stage of excavationcomple ted . Th is made thebasement structure at the centrevery r igid and from thereon,excavation to the sides continued,with the central part acting as a baseto shore-suppor t the newly

excavated sides. At certain points,basically along the bottom of GardenRoad and Battery Path, temporaryground anchors were installed as ameans to strength the diaphragmwall panels. The floor system in thebasement was of flat slab designwith dropped panel around column

heads. Average slab thickness was400mm (500mm thick for slab on thelowest basement, no ground beamwas provided).

To facilitate the removal of largevolume of excavated materials,several temporary openings wereformed on the basement slab so thatthe excavated soil could be removedby lifting grips, buckets of excavatingmachines (in stages) or partly by

dumper truck entering into thebasement through temporary ramp.

SuperstructureStructural systemThe Cheung Kong Center is acomposite structure with the innercore (measured approx. 22m x27m) constructed of Grade 60concrete and the external envelope

in concrete filled steel tubes. Thesize of the floor plate measuredabout 47m x 47m. The externalframe and inner core is tied withsteel beams, which topped with acomposite deck of 130mm thick.The span of the steel beams variesfrom about 10m to 14m and of sizein 457 x 191 series. In order toprovide an entrance lobby with a

more spacious look, there are only8 super-columns, each in size 2.5min diameter, supporting the entirebuilding, leaving a clearance of twocolumns at each elevation.

To economize the structure, atransfer truss system is provided onthe 2nd and 3rd level so that closer

spaced columns can be used in thedesign for the upper floors. Thesecolumns are in the form of concretefilled steel tube with section inuniform thickness (12.7mm) andranging from 1.42m in diameter forthe lower floors to 0.96m for the topfloors. The tube columns will begrouted by pumping concreteupward for every 3 floors.

In order to minimize the effect of

deflection due to wind load, 3 setsof outrigger/belt truss systems areprovided at the 22nd/23rd, 41st/42nd and 61st/62nd levels. Ananchor frame is embedded in thecore wall to provide adequateconnection to the outrigger frame.The outriggers and the belt trussesare structurally separated in orderto allow it to have limited movement

during wind, while maintainingsufficient strength and rigidity tosupport the entire building structure.

Core wallThe structural design of the core wallresembles two linked I sections(refer to drawing) with flangethickness ranging from 1500mm forthe lower floors and reduced

gradually to 400mm for floors abovethe 44th level, and web thicknessfrom 600mm to 400mm respectively.The core was constructed using aJump-form system designed on aworking cycle aiming at an averageof 3 days per floor (4.2m floor tofloor). The progress was in principle

maintained with the anticipation ofcertain delay at levels where theoutriggers located, as well as inlevels where the thickness of corehad to be reduced. Floor slabsinside the core were cast in-situ at adeferred stage. Internal partitionsinside the core including walls to liftshaft and staircases were erectedusing drywall system to eliminateunnecessary formwork or wet work.

Erection of the steel frameThe first lot of structural elementsto be erected for the superstructurewere the eight super-columns, thatembedded and stood on the top ofthe 6m diameter caisson which wasabout 25m below ground level. Thetransfer truss frame was thenerected on top of the super-columns.

To enable the truss be erected safelyand firmly at this level, a temporarysupport structure was first erectedonto the head of the super-columnsas a working base. Since this 8.75mhigh transfer truss was leaningoutward from the building line byabout 1.8m, the procedure andsequence to erect the entire transferstructure would be quite crucial.


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Detail method statement andproposal showing the erectionprocedure and sequence wasrequired to submit for approvalbefore actual carrying out of work.

The erection of the typical floorsworked basically under a 3-storeycycle to cope with the length of the

circular steel tube (concrete filledcolumns) on the exterior of thebuilding. When the steel tubes werepositioned and aligned, they werefurther secured by the connection ofthe steel beams. Connection wasdone by using tension control boltswith the inner end bolted to gussetplates that fully embedded in thecore wall.

After the steel beams were put in

place and secured, metal deck waslaid on top acting as the permanentshutter for the forming of thecomposite floor. Shear studs werealso welded on top of the beams to

improve the ability to take up shearby the floor membrane. Reinforcingbar was then fixed on top of the deckbefore the placing of concrete.

Provision of plant and equipmentThe heaviest members used in theproject were the steel stanchion for

the 8 super-columns, the weight ofeach fabricated section is about 25tons. Since these members wererequired to place into to 6m diametercaissons, crawler mounted cranecould be used for the lifting purposedin this case.

Since the formwork system usedfor the construction of the core wallwas of self-climbing type, noadditional cranage requirement was

thus needed to faci l i tate theoperation of the form system.However, the cranage demand forthe erection of the structural steelframe for the 62-level superstructure

as well as for the laying of thecomposite floor deck were still verygreat. To cater for this requirement,two tower cranes with luffing jib with600 Tm, one with fixed jib about halfthe capacity, were used to assist inthe l i f t ing of al l the requiredm a t e r i a l s , m e m b e r s a n d

components during the erectionprocess. The cranes werehydraulic-lifted and mounted insidethe voids of the core wall andsupported on temporary I-beams.

Two concrete pumps werestationed at ground level. They wereused mainly for the placing of concretefor the core wall, concrete filled tubethat used as columns, and thecomposite floors. Concrete delivery

pipe that fixed and housed inside thecore wall were used conveniently forthe purpose. The pipe would then beextended at the same time as thestructure ascended.

ConclusionThe Cheung Kong Center is a typicalcombination of modern constructiontechniques and methods. The useof top-down method to construct adeep basement , compos i testructure of very large scale andsize, the use of certain kind of

mechanical formwork for a particularpart of the structure, or even somemore sophisticated finishing itemssuch as curtain wall, raised floor, orbuilding services provisions whichintegrated with large amount ofin format ion and automat iontechnology. These are not new tothe construction industry nowadays.The art of executing this kind ofproject is that, whether the works

can be done in a cost effective,punctual, orderly and safe manner.In this respect, Cheung Kong Centeris undoubtedly a remarkable projectthat justifies the competence andprofessionalism of the buildingindustry of Hong Kong.


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Viewing the demolition process of

the Hilton Hotel from an elevatedposition. The work arrangement canbe clearly observed from the layoutof the demolition machines and thepositioning of the dumping shafts


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Overview of the demolition work down to the basement level. The ground floor and the slab of the first basement at this stage had been removed. Thesecond basement was backfilled with mixed materials to balance the earth pressure from the basement sides. Note also the remained portion ofbasement structure along the building boundary and the steel shoring supports being erected forming part of the stabilization measures for the partlydemolished basement structure


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Overview ofthe demolitionwork on thepodium level


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The commencement of work for thediaphragm wall after the completionof the demolition. The ground levelas seen in the photo was formed bythe backfilling of the old basementvoid. The guide wall for the formingof the 37m diameter cofferdam usingdiaphragm wall panels can roughlybe seen here

Another view of the partly demolished basement as seen from the previousfootbridge crossing the junction of Garden road and Queens Road Central

Closer view showing the temporarysteel shoring support and theremaining basement edge framecounter acting the ground pressurefrom the old basement wall


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A view of the site at the corner of Garden Road and Queens Road junctionseeing the diaphragm wall equipments (from the left: the bentonite treatmentand desanding plant, the hydrofraise trench cutter and the trench excavating

clamp shell, all yellow in colour)

Excavation to form the 37m diameter cofferdam in which the central coreof the future building positioned. The side of the cofferdam was lined with1.2m thick diaphragm panels stiffened by ring beams in 4 layers (the firsttwo layers can be seen in the photo)

The cofferdam excavateddown to its formation levelwhere the bedrock located


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The rising of the building core from the cofferdam pit.The work deck as seen inside the pit was the set ofJump-Form for the casting of the core structure. Notealso the steel stanchions on the side of the pit. Theywere the super-columns supporting the external frameof the future building

Viewing inside the cofferdam pit with the jump-form forthe building core structure in its operating condition


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An elevated view of the Cheung KongCenter site taken in mid-1997 with thebuilding core and the super-columnsin place. The building on the left sideof the cofferdam was the previousmulti-storey Garden Road carparkwhich was demolished 2 years afterthe taking of this photo forming the

phase 2 development (undergroundcarpark) of this project

Closer look of the cofferdam with the formwork decking inside and thelayout of the super-columns clearly seen


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Scaffold erected inside the cofferdam ready for the construction of theground floor slab. The core wall at this stage was completed up to

The whole set of formwork for the building core can beseen clearly at this position just above the ground level.The 6m diameter caisson in the foreground for the super-column, totally eight numbers, is also an eye-catchingobject at this stage of work

Viewing inside the 6m caisson with the steel stanchion for the super-columnbeing erected by embedded firmly onto the foundation concrete


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Rising of the tower structure from the

central core and the super-columnswith the Garden Road multi-storeycarpark and the high-rise residentialestates on the hill slope in the CentralMid-Level as its background


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One of the muck openingsprovisioned in the ground slab

for the loading and unloadingof plant equipments, materialsand excavated spoil during theconstruction of the basementusing top-down arrangement

A typical view seeing a section ofthe basement with excavationproceeded at the lowest level, acompleted basement slab on thetop, and the middle slab underconstruction using double-bitarrangement

Another v iew o f thebasement interior withdiaphragm wall (left, alongGarden Road) on one sideand a super-column on theother. The layers of steelstrut were erected tostabilize the diaphragmwall against the ground

pressure before the finalcasting of the permanentbasement slab


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Another temporary provision to form anopening to provide an access ramp intothe basement carpark before the phase 2carpark was put into operation

Detail showing the construction of a basement portion alongthe perimeter wall using double-pit method. Note also theconstruction of the basement wall using in-situ reinforcedconcrete in addition to the permanent diaphragm wall


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Another key element in the superstructure construction of the tower - the erection of the transfer truss system at the 3rd level. The truss provides awider span for the building entrance lobby using 8 numbers of super-columns. With the use of this transfer truss, the span-width of the external framefor the upper structure could be reduced to normal configuration. The steel frame as seen below the truss system is only the temporary falsework tofacilitate the erection of the truss frame which weighed totally more than 700 tons


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Closer view of the partlyerected transfer truss withsome of the floor joistsserving as tie membersconnected onto the centralcore wall

Interior view of the transfer frame on the 3rd level. The truss system isabout 12o leaning outward. This makes the erection process extremelydifficult especially where the heavy weight of the elements was takeninto consideration


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A side view of the transfer truss after its completion. Note the change in thespan width of the external frame below and above the truss

Placing of the steel tube to form the external column based onconcrete-filled-tube design

View of building section showingthe core wall, external frame andthe floor joists connection fortypical floor at the upper level


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Floor joists connected onto thecentral core before the laying ofthe floor decking

View of a set of partly completed belt truss located on 42nd Level

Close-up of the belt-truss member where the connecting node for theoutrigger frame located


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Detail showing the connection of the tie member onto the base of the belttruss. The external column in the form of concrete-filled-tube can be seen

under the base

View of the belt truss connecting node with the final adjusted outriggerbearing support and the shim plate in position

External view of the belt truss connecting node and the final-fixedoutrigger support in place


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A wider view showing the entire outrigger frame stretching from the central

core toward the belt truss

Close-up of the belt-truss connecting node with the preliminarily placedshim plates before the final level tuning and welding connection

External view showing the overall extent of the belt truss andthe typical concrete-filled steel columns


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Welding operation to fine tune theconnection of the jointing between theconcrete-filled steel column and thebelt truss/outrigger frame

Inspection to ensure connectionbetween the belt truss and the outriggerusing shim plates was in its rightposition and level after the adjustmentof deflection due to initial loading


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Galvanized iron decking being placed onto the floor as the base form forthe reinforced concrete topping. Reinforcing bar would be fixed afterwardfollowed by concreting to form the composite floor slab. Note the shearstud welded onto the steel joist to ensure the perfect composition of theconcrete topping to its base frame


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An eye-catching external viewof the building frame with theHong Kong and ShanghaiBank Headquarter Building asits background


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Overview of a set of outrigger frame

on the 61st level clearly showing thegeometrical shape, its connectionarrangement to the building coreand the belt truss

External view of the upperstructure of Cheung Kong Centerwith the belt truss system locatedon the roof level still un-claddedwith curtain wall panels


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External view of the composite structure upto the first set of outrigger frame on 23rd level.The set of formwork for the construction ofthe core wall is the focus point in this photo

Close up view of the Jump-Form system for the core wall construction. Thesimple racks, yellow in colour with the appearance like a pair of chopstick onthe deck of the form, are the screw jacks used to lift the form system after eachconcreting cycle


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Worker getting into the wall form to inspect the fixing of steelbefore the placing of concrete. Note a set of screw jack on theright side of photo

Close up look of a set of screw jack with the motor, driving/turninggears and the screw mount in operating condition

Interior view of the jump form system. The space between wall formwork panels isthe shaft inside the building core. Temporary scaffold with hanging platform deck isprovided as part of the formwork setting to facilitate workers working safely andconveniently within the jump form


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View into one of the shafts inside the building core where liftlobby and staircase located from the roof top. The floor slabinside the core is cast in-situ using manual-operated timberformwork

Closer look into the core seeing the erection of the floor formwork for thelift lobby

Steel members used in this project were first delivered to a temporaryhandling yard located in Tseung Kwan O before the final transportation tosite for actual installation


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A steel member belong to the belt truss system was lifted by tower crane,which had a lifting capacity up to 18 tons within a working radius of 30m

Final dismantling of the tower crane after the main structurehad been topped-out. There were three set of tower cranesbeing erected during the construction process. The craneswere dismantled in carefully scheduled manner when thebuilding was closed to top-out, with the operating one helpedto dismantle the crane scheduled for removal. A temporarycrane was finally installed to help to dismantle the last crane.After that, the temporary crane was dismantled by the helpof a simple lifting rod equipment with a winching machine


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Interior view of the outrigger and belttruss on the 41st level which is beingused as a refuge floor for fireescape. Note the fire-resistingplaster coated on the surface of steel

The construction of the floor slab on the 2nd level using a retro-installation arrangement.The floor in the form of a steel framing with concrete topping, was constructed after thecompletion of the upper structure (the transfer truss) in order to avoid the limited workingspace during the erection of the massive transfer truss structure


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External view of the composite structure up to 40thlevel before the installing of the curtain wall panels.The floors covered with plastic sheet were doingthe fire-resisting plaster which was applied to thesurface of steel by spraying action

External view of thebuilding with thecurtain wall on thelower floors beinginstalled


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Close up of the curtain wall installationbefore the enclosing of the belt trusson the 40th floor, which is using panelswith louvre strip to provide ventilationfor the plant/refuge floors instead ofstandard glazing

Another close up view with curtainwall installation approaching thebelt truss system on the 61st level


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Installing a standard curtain wall panel by workerwith the help of a simple rail-mounted electric blockstationed at upper level

S e t - u p o f t h ebuilding interior forthe storing of thecurtain wall panelsa n d o t h e r accessories. Notealso the dry wallp a r t i t i o n l i n e doutside the centralcore wall forming theservicing cubicles forthe required E & Mfacilities

Typical floor trunking network laid ontop of the floor screeding for therunning of wiring works before theinstalling of the raised floor system

Running of the wiring cable into the floor trunk before thefinal covering up of the raise floor panels


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Building exterior as seen from the Queens Road Centrallevel. The louvre panels covering the transfer truss from2nd to 3rd floors can clearly be observed. The entranceon the right is the permanent vehicular access point intothe basement carpark comprising of the phase one (areaunder the tower) and phase two (previous Garden Roadcarpark) facilities


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Another very eye-catching structuralelement of Cheung Kong Center isa footbridge linking pedestrians fromQueensway and Garden Road intothe entrance lobby of the building.This bridge obtained the Hong KongInstitution of Engineers (HKIE) andInstitute of Structural Engineer(IStructE) Joint Structural DivisionSpecial Award in 2002 due to itsinnovative structural design

Another view of thefootbridge as seenfrom Garden Roadtoward Queensway


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Various views of the footbridge asseen on the deck level. The elegantand curvilinear design, finished inlinen-finished stainless steel andglass, is its main visual attraction


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Section showing the temporary and permanentground works including the diaphragm wall on thesite parameter, 37m cofferdam pit, bore piles, raftfoundation for the core and the core wall structure


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Section showing the construction sequence of the top downbasement using double-bit excavation arrangement

Section showing the constructionsetting for the superstructure


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Elevation of the transfer truss system from the 2nd to 4th level with indication ofthe installation sequence and the temporary support falsework (in dotted line)


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Typical outrigger elevation and theconnecting node to the belt truss


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Framing plan for typical floorshowing the layout of corewall and the steel beams

Chueng Kong Centre Construction

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