Advanced Technology

Examples of Advanced Technology Employed in the Construction of Buildings in Hong Kong

Steel formwork is becoming quite common, especially in buildings with regular, identical or repeated layout. The one in the photo is used in the construction of Harmony blocks, a common building technique employed in Housing Authority projects.

The 'Jump Form', another type of highly mechanised formwork system, used in a Concord block public housing project. This system can lift itself up by a jacking device when the concreting work of a floor is completed. As individual formwork panels are hung under a sliding rail, the system can thus save a lot of time and effort in the striking and placement of the formwork panel.

A closer look at the Jump Form shows that the track rail can enable the formwork panel slide into position.

Steel formwork for beams is uncommon. The example shown is specially designed for the new Headquarters building for the Hong Kong Jockey Club. It is a composite construction making use of precast secondary beams and sub-slabs to form the podium structure.

Formwork is one of the most challenging elements of work in the construction of high-rise buildings, mainly due to complicated spatial, loading or scheduling requirements. Though there are many advanced formwork systems available, traditional timber formwork is still widely used for building construction in Hong Kong due to its flexibility in meeting with various layout requirements.

Another common type of steel formwork is of a vertical attaching nature, which can 'climb' in a free-standing manner. This is more suitable for situations like a central core of a building which has lift shafts.

Another example of specially designed steel formwork to suit a particular shape and purpose: the example shown here was used as a pier for an elevated motorway.

Formwork shaped like shutter panels can be used in complex arrangements, like the one here for the wall of a circular ramp.

The principle of formwork is simple, but performing the installation under site conditions may be quite difficult. Depicted here is the erection of the final section of formwork for a 9 m circular column which encases the steel stanchion for a structural steel building.

'Table Form' made of aluminium sections is growing in popularity, especially for commercial/office buildings making use of flat-slab design. The one as shown here is the Gateway II project.

The 'Climb Form' under the VSL system, was used for the Lee Garden Redevelopment project.

The Jump Form system was used for the Cheung Kong Center project.

The principle of using Table Form seems simple, but many connecting details require solution before satisfactory application. The example here, with the floor slab connecting to the central core, best illustrates the situation.

Another tailor-designed formwork was used to construct the elevated expressway at Ma Wan, which is part of the Lantau Link. The formwork was composed of a gantry frame that hung the shutter panels for the inner-wall of the box-section expressway. Again, it could be slid to a new position on track rail to repeat works conveniently.

The VSL Climb Form utilised to construct the building core for the International Finance Centre adjacent to Hong Kong Station at Central. Two sets of identical formwork were installed to form the large regularly shaped central core. This helped acquire the best operational efficacy by splitting the core into two halves, as well simplifying the construction and size of the formwork.

Close-up of one set of the two identical Climb Form systems used in the construction of the International Finance Centre. Since the size of the form has been reduced by dividing it in two, the main supporting frame for the formwork system is obviously much simpler than the one used by the Lee Garden Redevelopment project.

A panoramic view from the top deck of the Climb Form system for the Lee Gardens Redevelopment project. Main features such as the main supporting frame, the hydraulic jack rod, and the wall section with reinforcing bars already in place, can be clearly seen here.

A formwork system combining steel trusses and glass-reinforced plastic shutters were used to construct the complicated roof of the Ground Transportation Centre situated at the entrance to the Airport Terminal building.

A combined formwork and falsework system used in the new airport terminal. The whole system can be released and slid to a new position on track rail. The system can best serve where a lengthy, repetitive section of elevated platform is required like the passenger unloading deck shown here.

Low-rise buildings of structural steel construction are rarely used in Hong Kong, but a few examples are found in the new airport at Chek Lap Kok. The example shown here makes use of metal panels as the external cladding system. (Asia Air Terminal)

Cladding system employed for the Cathay Pacific Catering Services project at Chek Lap Kok.

Another example of metal-panel cladding: the Air Mail Centre at Chek Lap Kok operated by the Hong Kong Post Office.

The challenge of providing building services to modern high-rise buildings taxes technological and engineering concerns. Accommodating the services safely, neatly and effectively inside the limited space of building in the design is the goal. Shown here is a switch room with hundreds of power cables, demonstrating the complexity of such services. (The Centre)

One of the basic provisions for grade A office space is a serviceable floor providing access for IT cabling. The one shown here is a typical raised-floor system with a 250 mm floor void. The separating panels inside the floor (and in the ceiling) are fire breaks made of cement board.

Large amounts of glass are often used as roofing in the form of skylights. The one seen here (Festival Walk) uses over 5,000 sq m of glass as skylight to provide natural illumination for the river-like atrium. To provide a clear span of 30 m with strict waterproofing and dimensional performance is an exceptionally demanding requirement.

Shown here are construction works for the Airport Railway tunnel section in the Western Kowloon Reclamation. The sides of the 8 m excavation are supported using steel sheet piles and further stabilised by a complicated steel strut frame. Control of ground water was crucial on this newly reclaimed land. The RC tunnel section was then constructed upward from the bottom of the excavation.

A drilling machine was used to prepare bore holes for the insertion of steel tendons to form the ground anchor.

The photo shows a 12 m deep excavation for the Airport Railway tunnel section at the Central Reclamation near Hong Kong Station. A relatively 'obstacle free' method was used to support the excavation, and soldier piles supported laterally by ground anchors were also employed.

The top-down construction method is virtually the only method suitable for the construction of deep basements on a large scale. One irresistible advantage of this method is that substructure and superstructure work can be carried out at the same time. The one seen here depicts the basement entrance for the Cheung Kong Center project, which best illustrates the method.

Top-down basement construction: the permanent RC structure at the top has been completed but remains supported on temporary steel stanchions, while the excavation and construction work to the lower basement is yet to be continued. (Lee Gardens)

Another complication in the construction process involves sub-structures: the foundations, extensive groundwork, basement construction. The work seen here is a heavily reinforced 4.5 m raft which acts as the foundation cap for the building. The steel shore at the centre, which radiates outward to support the sides of the excavation, can also be seen.

The Festival Walk project presented an extremely complicated case with very difficult substructure works. Complicating factors included the huge site area, the inconsistent subsoil conditions, the MTR tunnel cutting across the site, the top-down basement construction method used and the segmental phasing arrangement in the overall construction.

Another feature of top-down construction is that the ground floor slab (indeed, any slab close to ground level) is cast first as a starting level to provide the necessary rigidity to the side supports. This example, from the Festival Walk project, best illustrates the arrangement.

This drilling rig works with a steel casing for soil support during the excavation process, drilling bit for the actual digging/drilling, soil grab for the removal of soil and chisel hammer to break harder rock, can be used to construct concrete bore piles up to 2.75 m in diameter.

One reason for recent advances in building construction is the steady improvement of machinery used in the construction of foundations. This example is a compact-sized drilling machine which can be used to construct in situ concrete bore piles ranging from 150 mm to 450 mm in a congested urban environment.

The reverse-circulation drilling machine, combined with a rig-like turntable mounted on top of the steel casing, requires a set of suction pumps and a de-sanding machine to facilitate drilling. Soil or gravel is pumped up from the excavated trench by ground water circulation. At the same time, the de-sanding machine removes soil particles from the ground water and recycles it in the drill hole.

Most recent curtain wall systems used in Hong Kong are the unitised system: The wall is composed of identical panel units and attached to the main structure directly without a main bearing frame. The photo shows the installation of curtain wall at the Lee Gardens Redevelopment project.

Difficulties encountered in the installation of curtain wall are often due to irregular building shape and awkward angles. The picture illustrates these problems (The Centre).

Modern construction strives to provide an attractive, energy-efficient, weather-tight external envelope. Curtain wall is one of the most popular options for commercial and office buildings. This example depicts the main skeleton of a building before curtain wall units are attached to its outer face.

Another new machine, the reverse-circulation trench cutter or hydrofraise, is very efficient for the construction of diaphragm wall. Working similar to the principle of reverse circulation drilling machine, it requires bentonite slurry as the recycling medium instead of ground water. Several pairs of drum cutters at the tip of the hydrofraise do the actual cutting. The box-sectioned cutter rack produces a section of uniform thickness for the diaphragm wall panel.