Extension to the Hong Kong Convention & Exhibition Centre

Extension to the Hong Kong
nvention & Exhibition Centre

The extension portion to the Hong Kong Convention and Exhibition Centre (HKCEC) was constructed on a reclaimed 6.5 ha island site. The project took only 48 months from reclamation to completion, which is extremely fast for a building project of this size. The HKCEC has a total internal exhibition area of more than 28,000 sq m with 16-metre headroom and spans ranging from 26 m to 81 m. Its multi-curved steel roof has a total area of 40,000 sq m, while the 7,000 sq m fully glazed main entrance foyer has a clear headroom of about 60 metres.

About 350,000 cu m of marine mud was dredged and 1.8 million cu m of rock and sand fill could be placed. At the same time, seven box-shape structures were built off-site and sunk to the northern seawalls; these formed the pump houses for the cooling systems of the HKCEC and its associated buildings. Due to time pressures, piling began almost immediately after land was reclaimed. A total of about 3,000 steel H-piles were driven to an average depth of 40 m.

The single basement level is used mainly as carpark. Its formation level is about 50 cm higher than mean sea level, so the problem of seeping during construction was not critical. The basement was founded on a 350 mm flat slab with an enclosing perimeter wall of 400 mm thickness.

For the superstructure, the two groups of service core walls support the composite floor deck of the exhibition halls as well as the 81-metre span roof trusses. The two core walls are essentially symmetrical with a slight curve on the outer face. Each measures about 15 m in the waist, 150 m long and 65 m high, with staircases and lifts located inside.

The floor of the 3 exhibition halls was constructed using a steel truss/RC composite deck structure supported in the middle by four pairs of composite steel columns in a 27 m x 27 m grid. The side wings on the east and west side of the service core wall were of typical RC construction.

The main roof is a steel structure over a 8,500 sq m column-free exhibition hall and a 6,000 sq m convention hall. To construct the roof, six 280-tonne primary steel trusses were fabricated off-site and lifted to the top of the core wall using two pairs of strand jacks. After positioning onto the pot bearers anchored to the core wall, secondary trusses were erected between the primary trusses to stabilise the roof frame and support the purlins for the roof deck. The roof deck itself was of multi-layered construction with an average depth of 750 mm. It is composed of an under-laid deck, ash-grid system (to adjust for the true curvature), insulation layers, cement boarding, waterproofing sheets and a PVDF coated aluminium-alloy roof skin.

Save the east-facing granite slab external walls , most exteriors are of glazed wall design. The glass walls are hung from the roof and supported by vertical or/and horizontal trusses spanning between floors and columns. For the interiors, all steel columns and other bracing members are clad in fibre-reinforced concrete panels. For other concrete wall and floor surfaces, granite and marble slab are the main finishing materials.

main contractor
Hip Hing Construction Co Ltd/Dragages et Travaux Publics – joint venture

A Splendid Symbol of Hong Kong

The overall site layout from June 1995, when the building superstructure had just commenced. At this stage, the pair of 150m-long reinforced concrete cores is the most prominent structure at the site.

In this photo from September 1995, progress can be seen in the southern part of the building. The reinforced concrete core, which was constructed in stepped sections using a patented shuttering system, functioned efficiently after a three-month period of continual work. Some of the steel trusses for the floor structure of the Level 2 Exhibition Hall, including the first two pairs of supporting columns, was installed. To reduce construction costs, the floor slab of Level 1 Exhibition Hall was constructed of reinforced concrete (rather than structural steel) as there was no need to provide a large-span design for the ground floor area.

The southern portion of the reinforced concrete core topped out in November 1995. The erection of the steel decking for the floor slab was in full progress from the southern end to the seaward direction. The steel deck was concreted afterward to form a rigid composite floor structure.

In February 1996, less than 10 months from the commencement of the main building structure, the first section of the main roof truss was in position. The three levels of the Exhibition Hall, with the floor slab for Level 1 made of reinforced concrete, and Level 2 and 3 of structural steel construction, can be clearly seen in this photo.

July 1996: The construction of the linking bridge for the old and new convention and exhibition centre can be seen here.

A bird’s eye view showing the entire roof structure in August 1996. The laying of the 750 mm multi-layered roof decking had just begun.

Close-up of the gigantic structural steel frame used to span the 80 m exhibition space between the pair of reinforced concrete cores.

The most difficult part of the installation: One of the 400-tonne main roof trusses is placed on a lifting girder in preparation for elevation to the top of the core wall.

Top-down view of the roof truss: The 20 m slot on the core wall provided towing access for the steel truss. This slot was reclaimed after the lifting process by the addition of reinforced concrete. Note the temporary unloading pier and the barge employed to deliver the roof trusses and other heavy components to the site.

Beginning stage for the shuttering system of the 150 m reinforced concrete core structure at the building’s centre. The HKCECE project has a one-level partial basement which is mainly used for mechanical facilities; this made the construction process relatively uncomplicated

In a six-hour process, the roof truss was lifted to the top of the core wall by two pairs of strand-jacks.

The set-up of the strand-jack, its steel support columns, and the rail track facilitating the sideways sliding action of the steel truss can be seen in this photo.

Close-up of the strand-jack devices. After the lifting process, the jack would be temporarily removed so that it would not impede the sideways movement of the truss.

The first two trusses that are seen after braced with the fill-in members. An unobstructed 80 m space is not a easy distance to span using any lightweight structure.

The truss undergoing alignment on the top of the core wall. Using a synchronised horizontal jack on each end, the truss was pushed sideways until it reached the predetermined position on the core wall.

The first two trusses in position. The space between the steel trusses was braced with tie members which eventually unified the entire roof into a continual, eight-metre deep, two-way structure with an 80 m span.

Supporting detail of the roof truss. The weight of the main roof (about 4,200 tonnes excluding the apron areas) is supported by 24 bearer-plates which are rooted to the core wall structure. At this stage, the truss is temporarily rested on the bearers. It will be further adjusted by hydraulic jacks when the entire roof structure with all the articulating members is installed in its final position.

The gradual extension of the roof structure with the unit-by-unit addition of the prefabricated steel trusses. The floor below is of composite steel/reinforced concrete slab design. The rows of shallow trenches are the service channels, which are concealed in a raised floor system constructed of lightweight/expanded polystyrene filled concrete to be laid at a later stage.

The anchor bolts provided inside the concrete on top of the core wall for the support of the roof structure.

The connecting members for the multiple-curved apron of the roof stretching out from the main roof frame structure.

The complicated space inside the roof truss. The space here is eight metres deep on average, and curves to more than 15 metres deep in some sections. It will be provided with service-access in the form of a suspended cat-walk, and used mainly to accommodate building services such as distribution ductwork for the HVAC systems.

The suspended access gangway is erected using timber planks. It forms an elegant curve at the edge of the roof.
Procedures to install the roof trusses
  1. Primary truss frame transport to site from the Philippines by barge

  2. Truss slip into the reserved slot provided in the core wall

  3. Truss being lifted to the roofl evel by strand jacks

  4. Truss being slid to its final position by hydraulic jacks

  5. Installing the cantilever truss later by crane

The complicated geometry of the roof structure is shown here at the junction where two curved sections of the main roof and apron attachment meet.

The same portion of the roof with the undermost layer of galvanised steel deck panel installed. Access provision, basically in the form of bamboo scaffolding, is provided here.

The skeleton of the roof structure above the Grand Foyer. Although it gives a slender look from a distance, the actual structure is a heavy one. The worker in the photo indicates the scale and mass of the roof.

A typical junction inside the steel roof truss. At certain points, up to 16 steel members meet at one junction. The angles are awkward until the member reaches another connecting point opposite. The problem of dimensional co-ordination was a significant issue throughout the entire project.

The layout and basic structural arrangement of the main roof as seen from the cabin of the tower crane.

A portion of the partly finished, multi-layered roof deck as seen on a chilly winter dawn.

A splendid look at the two wings of the eastward-facing aprons during the erection of the roof decking system.

The 37,000 sq m roof surface needed finishing both on the top and on the underside. In the photo, workers are working on a temporary platform to install the metal-stripped soffit on the underside of the projecting roof apron. The purlin rail and bracket system that provide the shape and form of the final roof can also be seen.

Another complicated junction detail of the partly finished roof where three curved roof surfaces met. Naturally, this kind of junction formation together with the extraordinary large surface area of the roof created a drainage problem for rainwater; The only solution was effective waterproofing design.