Central Plaza (Hong Kong)

Central Plaza
中環廣場
Central Plaza by day in April 2003
General information
Status	Complete
Type	Commercial offices
Architectural style	Postmodern
Location	18 Harbour Road Hong Kong
Coordinates	22°16′48″N 114°10′25″E / 22.28000°N 114.17361°E / 22.28000; 114.17361Coordinates: 22°16′48″N 114°10′25″E / 22.28000°N 114.17361°E / 22.28000; 114.17361
Construction started	1989
Completed	1992
Height
Architectural	373.9 m (1,227 ft)
Roof	309 m (1,014 ft)
Top floor	299 m (981 ft)
Technical details
Floor count	78 3 below ground
Floor area	172,798 m2 (1,859,982 sq ft)
Lifts/elevators	39
Design and construction
Architect	Dennis Lau & Ng Chun Man Architects & Engineers (HK) Ltd.
Developer	Ryoden Development Sino Land Sun Hung Kai Properties
Structural engineer	Arup
Main contractor	Manloze Ltd
References
[1][2][3][4]

Central Plaza is a 78-storey, 374 m (1,227 ft) skyscraper completed in August 1992 at 18 Harbour Road, in Wan Chai on Hong Kong Island in Hong Kong. It is the third tallest tower in the city after 2 International Finance Centre in Central and the ICC in West Kowloon. It was the tallest building in Asia from 1992 to 1996, until the Shun Hing Square in neighbouring Shenzhen was built. Central Plaza surpassed the Bank of China Tower as the tallest building in Hong Kong until the completion of 2 IFC.

Central Plaza was also the tallest reinforced concrete building in the world, until it was surpassed by CITIC Plaza, Guangzhou. The building uses a triangular floor plan. On the top of the tower is a four-bar neon clock that indicates the time by displaying different colours for 15-minute periods, blinking at the change of the quarter.

An anemometer is installed on the tip of the building's mast, at 378 metres (1,240 ft) above sea level. The mast has a height of 102 m (335 ft). It also houses the world's highest church inside a skyscraper, Sky City Church.

Design

Main Lobby

Central Plaza is made up of two principal components: a free standing 368-metre-high (1,207 ft) office tower and a 30.5-metre-high (100 ft) podium block attached to it. The tower is made up of three sections: a 30.5-metre-high (100 ft) tower base forming the main entrance and public circulation spaces; a 235.4-metre-tall (772 ft) tower body containing 57 office floors, a sky lobby and five mechanical plant floors; and the tower top consist of six mechanical plant floors and a 102-metre-tall (335 ft) tower mast.

The ground level public area along with the public sitting out area form an 8,400 m² (90,000 sq ft) landscaped garden with fountain, trees and artificial stone paving. No commercial element is included in the podium. The first level is a public thoroughfare for three pedestrian bridges linking the Mass Transit Railway, the Convention and Exhibition Centre and the China Resource Building. By turning these space to public use, the building got 20% plot ratio more as bonus. The shape of the tower is not truly triangular but with its three corners cut off to provide better internal office spaces.

Design constraints

The Sky Lobby

Triangular shaped floor plan

The building was designed to be triangular in shape because it would allow 20% more of the office area to enjoy the harbour view as compared with a square or rectangular shaped buildings. From an architectural point of view, this arrangement provides better floor area utilisation, offering an internal column-free office area with a clear depth of 9 to 13.4 m (30 to 44 ft) and an overall usable floor area efficiency of 81%. Nonetheless, the triangular building plan causes the air handling unit (AHU) room in the internal core to also assume a triangular configuration. With only limited space, this makes the adoption of a standard AHU not feasible. Furthermore, all air-conditioning ducting, electrical trunking and piping gathered inside the core area has to be squeezed into a very narrow and congested corridor ceiling void.

Super high-rise building

As the building is situated opposite to the HKCEC, the only way to get more sea view for the building and not be obstructed by the neighbouring high-rise buildings is to build it tall enough. However, a tall building brings a lot of difficulties to structural and building services design, for example, excessive system static pressure for water systems, high line voltage drop and long distance of vertical transportation. All these problems can increase the capital cost of the building systems and impair the safety operation of the building.

Maximum clear ceiling height

As a general practice, for achieving a clear height of 2.6 to 2.7 m (8.5 to 8.9 ft), a floor-to-floor height of 3.9 to 4.0 m (12.8 to 13.1 ft) would be required. However, because of high windload in Hong Kong for such a super high-rise building, every increase in building height by a metre would increase the structural cost by more than HK$1 million (HK$304,800 per ft). Therefore, a comprehensive study was conducted and finally a floor height of 3.6 m (12 ft) was adopted. With this issue alone, an estimated construction cost saving for a total of 58 office floors, would be around HK$30 million. Yet at the same time, a maximum ceiling height of 2.6 m (8 ft 6 in) in office area could still be achieved with careful coordination and dedicated integration.

Structural constraints

Sky City Church lounge area in the Apex

• The site is a newly reclaimed area with a maximum water table rises to about 2 m (6 ft 7 in) below ground level. In the original brief, a 6 storey basement is required, therefore a diaphragm wall design came out.
• The keyword to this project is time. With a briefing in a limited detail, the structural engineer needed to start work The diaphragm wall design allowed for the basement to be constructed by the top-down method. It allows the superstructure to be constructed at the same time as the basement, thereby removing time consuming basement construction period from the critical path.
• Wind loading is another major design criterion in Hong Kong as it is situated in an area influenced by typhoons. Not only must the structure be able to resist the loads generally and the cladding system and its fixings resist higher local loads, but the building must also perform dynamically in an acceptable manner such that predicted movements lie within acceptable standards of occupant comfort criteria. To ensure that all aspects of the building's performance in strong winds will be acceptable, a detailed wind tunnel study was carried out by Professor Alan Davenport at the Boundary Layer Wind Tunnel Laboratory at the University of Western Ontario.

Steel structure vs reinforced concrete

Steel structure is more commonly adopted in high-rise building. In the original scheme, an externally cross-braced framed tube was applied with primary/secondary beams carrying metal decking with reinforced concrete slab. The core was also of steelwork, designed to carry vertical load only. Later after a financial review by the developer, they decided to reduce the height of the superstructure by increasing the size of the floor plate so as to reduce the complex architectural requirements of the tower base which means a highstrength concrete solution became possible.

In the final scheme, columns at 4.6 m (15 ft) centres and 1.1-metre-deep (3.6 ft) floor edge beams were used to replace the large steel corner columns. As climbing form and table form construction method and efficient construction management are used in this project which make this reinforced concrete structure take no longer construction time than the steel structure. And the most attractive point is that the reinforced concrete scheme can save HK$230 million compared to that of steel structure. Hence the reinforced concrete structure was adopted and Central Plaza is now one of the tallest reinforced concrete buildings in the world.

In the reinforced concrete structure scheme, the core has a similar arrangement to the steel scheme and the wind shear is taken out from the core at the lowest basement level and transferred to the perimeter diaphragm walls. In order to reduce large shear reversals in the core walls in the basement, and at the top of the tower base level, the ground floor, basement levels 1 and 2 and the 5th and 6th floors, the floor slabs and beams are separated horizontally from the core walls.

Another advantage of using reinforced concrete structure is that it is more flexible to cope with changes in structural layout, sizes and height according to the site conditions by using table form system.

Current tenants

• Kroll Inc. (17th Floor)^[5]
• Pinsent Masons (50th Floor)
• Zoomlion Hong Kong 57th Floor
• Sun Microsystems (66th Floor)^[6]
• English Schools Foundation (67-72nd Floor)
• Royal Saudi Consulate Of Hong Kong (Suite 6401, 64th Floor)^[7]
• AFP (62nd Floor)^[8]
• Clyde & Co (58th Floor)^[9]
• Chevron (Caltex) 41st Floor & 42nd floor
• CB Richard Ellis (30th and 34th Floors)
• ExxonMobil (23rd Floor)^[10]
• Towers Watson (21st Floor)^[11]
• Plaskim (11th Floor)^[12]
• Nvidia (10th Floor)^[13]
• CNBC Asia (54th Floor)
• Daimler AG (59th Floor)
• New Zealand Consulate-General Hong Kong (Suite 6501, 65th Floor)^[14]
• The Economist (60th Floor)
• Swiss Reinsurance Company (37th and 67th Floor)
• Consulate General of the Swiss Confederation (Suite 6206-07)
• Consulate-General of Italy in Hong Kong (Suite 3201, 32nd Floor)^[15]
• Basell Asia Pacific Ltd. (15th floor)
• [Cardell] (20th floor)
• [Amgen] (35th floor)
• LORD Asia International Limited (7th floor)

Gallery

• 
  Central Plaza, 20 April 2003
• 
  Central Plaza and the Great Eagle Centre, 19 May 2007
• 
  Triangular shaped floor plan of Central Plaza, 20 April 2003
• 
  Vertical shot of Central Plaza, 20 April 2003
• 
  A view of Wanchai waterfront with Hong Kong Convention and Exhibition Centre in the foreground and Central Plaza behind it, August 2005
• 
  A view of Wanchai waterfront as seen from Central Pier 9, Nov 2007
• 
  Flags at half mast, at the foot of Central Plaza

See also

• List of tallest buildings in Hong Kong
• List of buildings and structures in Hong Kong
• List of skyscrapers
• List of tallest freestanding structures in the world
• List of buildings

References

External links

Wikimedia Commons has media related to Central Plaza, Hong Kong.

• www.centralplaza.com.hk Official home site of the building.
• Architectural study of the building
• Hong Kong's skyscrapers in comparison
• Satellite view of the site
• Central Plaza Elevator Layout