Editing Central Plaza (Hong Kong)

{{short description|Supertall skyscraper in Wan Chai, Hong Kong}}
{{Use Hong Kong English|date=December 2018}}
{{Use dmy dates|date=April 2020}}
{{Infobox building
|name                = Central Plaza
|native_name         = {{lang|zh-HK|中環廣場}}
|image               = Hong Kong Convention and Exhibition Centre 200906(cropped).jpg
|image_size          = 200px
|caption             = Central Plaza in June 2009
|location            = 18 [[Harbour Road]]<br/>[[Wan Chai]], Hong Kong
|coordinates         = {{coord|22|16|48|N|114|10|25|E|region:HK|display=inline,title}}
|status              = Complete
|start_date          = {{Start date and age|1989}}
|completion_date     = {{End date and age|1992}}
|building_type       = Commercial offices
|architectural_style = [[Postmodern architecture|Postmodern]]
|architectural       = {{convert|373.9|m|ft|0|abbr=on}}
|roof                = {{convert|309|m|ft|0|abbr=on}}
|top_floor           = {{convert|299|m|ft|0|abbr=on}}
|floor_count         = 78 <br/>3 below ground
|elevator_count      = 39
|cost                =
|floor_area          = {{convert|172798|m2|sqft|0|abbr=on}}
|architect           = Dennis Lau & Ng Chun Man Architects & Engineers
|structural_engineer = [[Arup Group|Arup]]
|main_contractor     = Manloze Ltd
|developer           = Ryoden Development<br>Sino Land<br>Sun Hung Kai Properties
|owner               =
|management          =
|references          = <ref>{{ctbuh|277}}</ref><ref>{{Cite web |url=https://www.emporis.com/buildings/120372 |archive-url=https://web.archive.org/web/20151102141744/https://www.emporis.com/buildings/120372 |url-status=usurped |archive-date=2 November 2015 |title=Emporis building ID 120372 |work=[[Emporis]]}}</ref><ref>{{skyscraperpage|112}}</ref><ref>{{structurae|20004050}}</ref>
}}
{{Chinese
|t=中環廣場
|s=中环广场
|showflag=y
|y=Jūngwàahn Gwóngchèuhng
|ci={{IPAc-yue|z|ung|1|.|w|aan|4|-|gw|ong|2|.|c|oeng|4}}
|j=Zung1waan4 Gwong2coeng4
|p=Zhōnghuán Guǎngchǎng
|w=Chung<sup>1</sup>-huan<sup>2</sup> Kuang<sup>3</sup>-chʻang<sup>3</sup>
}}

'''Central Plaza''' is a 78-[[storey]], {{convert|374|m|abbr=on}} [[skyscraper]] at 18 [[Harbour Road]], in [[Wan Chai]] on [[Hong Kong Island]] in [[Hong Kong]]. Completed in August 1992, it is the third tallest tower in the city after [[International Finance Centre (Hong Kong)|2 International Finance Centre]] (2 IFC) in [[Central, Hong Kong|Central]] and the [[International Commerce Centre]] in [[West Kowloon]]. It was the tallest building in [[Asia]] from 1992 to 1996, until the [[Shun Hing Square]] was built in [[Shenzhen]], a neighbouring city. Central Plaza surpassed the [[Bank of China Tower (Hong Kong)|Bank of China Tower]] as the [[List of tallest buildings in Hong Kong|tallest building in Hong Kong]] until the completion of [[International Finance Centre (Hong Kong)|2 IFC]].

Central Plaza was also the tallest [[reinforced concrete]] building in the world, until it was surpassed by [[CITIC Plaza]], [[Guangzhou]] in 1996. 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 {{convert|378|m}} above sea level. The mast has a height of {{convert|102|m|abbr=on}}. Central Plaza also houses the world's highest [[Church (building)|church]] inside a skyscraper, Sky City Church.

==History==
The land upon which Central Plaza sits was reclaimed from [[Victoria Harbour]] in the 1970s. The {{convert|77800|sqft|sqm}} site was auctioned off by the [[British Hong Kong|Hong Kong Government]] at [[Hong Kong City Hall|City Hall Theatre]] on 25 January 1989. It was sold for a record HK$3.35 billion to a [[joint venture]] called "Cheer City Properties", owned 50 per cent by [[Sun Hung Kai Properties]] and 50 per cent by fellow real estate conglomerate [[Sino Land]] and their major shareholder the [[Ng Teng Fong]] family.<ref name="record">{{cite news|last1=Chan|first1=Chi-keung|title=Site sold for record $3.35 billion|work=[[South China Morning Post]]|date=26 January 1989|page=1}}</ref><ref name="tocost">{{cite news|last1=Chan|first1=Chi-keung|title=Wan Chai site development to cost $1.8b|work=South China Morning Post|date=27 January 1989|page=47}}</ref> A third developer, Ryoden Development, joined the consortium afterwards.<ref name="arupjournal">{{cite journal|last1=Ayres|first1=Peter|last2=MacArthur|first2=John|title=Central Plaza, Hong Kong|journal=Arup Journal|date=1993|volume=28|issue=4|pages=16–21}}</ref> Ryoden Development disposed off its 5% interest for 190,790 square feet of office space in New Kowloon Plaza from Sun Hung Kai in 1995.<ref>{{cite news |title=Central Plaza sell-off boosts Ryoden |url=https://www.scmp.com/article/132204/central-plaza-sell-boosts-ryoden |access-date=29 February 2020 |work=South China Morning Post |date=21 September 1995 |language=en}}</ref>

The first major tenant to sign a lease was the [[Airport Authority Hong Kong|Provisional Airport Authority]], which on 2 August 1991 agreed to lease the 24th to 26th floors.<ref name="PAA">{{cite news|last1=Moreira|first1=Peter|title=Central Plaza draws airport authority|work=South China Morning Post|date=3 August 1991|page=21}}</ref> A topping-out ceremony, presided over by Sir [[David Ford (civil servant)|David Ford]], was held on 9 April 1992.<ref name="heady">{{cite news|last1=Wigan|first1=David|title=New tower lures a heady mix|work=South China Morning Post|date=1 April 1992|page=29}}</ref><ref name="newheights">{{cite news|last1=Thompson|first1=Nick|title=Central Plaza reaches new heights|work=South China Morning Post|date=10 April 1992}}</ref>

==Design==
[[Image:HK Central Plaza 60407 1st.jpg|right|thumb|Main Lobby]]
Central Plaza is made up of two principal components: a free standing {{convert|368|m|ft|adj=mid|-high}} office tower and a {{convert|30.5|m|ft|adj=mid|-high}} podium block attached to it. The tower is made up of three sections: a {{convert|30.5|m|ft|adj=mid|-high}} tower base forming the main entrance and public circulation spaces; a {{convert|235.4|m|ft|adj=mid|-tall}} tower body containing 57 office floors, a [[sky lobby]] and five [[Mechanical plant|mechanical plant floors]]; and the tower top consisting of six mechanical plant floors and a {{convert|102|m|ft|adj=mid|-tall}} tower mast.

The ground level public area along with the public sitting out area form an {{convert|8400|m2|abbr=on}} landscaped garden with a 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 [[MTR|Mass Transit Railway]], the [[Hong Kong Convention & Exhibition Centre|Convention and Exhibition Centre]] and the [[China Resources Building]]. By converting these space for public use, the building gained 20% more plot ratio. The shape of the tower is not truly triangular with its three corners truncated to provide better internal office spaces.

Central Plaza was designed by the Hong Kong architectural firm Ng Chun Man and Associates (since renamed Dennis Lau & Ng Chun Man Architects, or DLN) and engineered by [[Arup Group|Arup]]. The main contractor was a joint venture, comprising the contracting firms [[Sun Hung Kai Properties|Sanfield]] (a subsidiary of Sun Hung Kai) and Tat Lee, called Manloze Ltd.<ref name="arupjournal"/>

=== Design constraints ===

==== 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 to 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 {{convert|9|to|13.4|m|ft|abbr=on}} and an overall usable floor area efficiency of 81%.
Nonetheless, the triangular building plan causes the [[Air handler|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 the [[Hong Kong Convention & Exhibition Centre]], the best to maximise the [[Victoria Harbour|harbour]] views for the building and to not be obstructed by the neighbouring high-rise buildings was to design it to be tall enough to clear the height of neighbouring buildings. However, designing tall buildings bring several difficulties in structural and building services design. For example, excessive system [[static pressure]] in water systems, high line [[voltage drop]], and a long distance of vertical transportation (resulting in long waits for elevators). All these problems can increase the capital cost of the building systems and impair the safety operations of the building.

==== Maximum clear ceiling height ====
As a general practice, achieving a clear height of {{convert|2.6|to|2.7|m|ft|abbr=on}}, and a floor-to-floor height of {{convert|3.9|to|4.0|m|ft|abbr=on}} would be required. However, due to the high [[Wind load]] in Hong Kong for such a tall high-rise building, every increase in building height per 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 {{convert|3.6|m|abbr=on}} 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 {{convert|2.6|m|abbr=on}} in office area could still be achieved with careful coordination and dedicated integration.

==== Structural constraints ====
[[Image:Sky City Church Lounge.jpg|thumb|Sky City Church lounge area in the Apex]]
*The site was a newly [[Land reclamation|reclaimed]] area with a maximum [[water table]] rise of about {{convert|2|m|abbr=on}} below ground level. In the original brief, a 6-storey basement was required, therefore a [[diaphragm wall]] design was chosen.
*The diaphragm wall design allowed for the basement to be constructed by the top-down method. It allowed 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]] was another major design criterion as Hong Kong is often affected by [[Typhoon|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 would 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 structures are more commonly adopted in high-rise buildings. 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 composed of steelwork, designed to carry vertical loads 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 high strength concrete solution became possible.

In the final scheme, columns at {{convert|4.6|m|abbr=on}} centres and {{convert|1.1|m|ft|adj=mid|-deep}} 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.

==Trivia==
[[Image:Central Plaza Sky Lobby.JPG|right|thumb|The ''Sky Lobby'' on the 46th floor was visited by American TV show ''[[The Amazing Race 2]]''.]]
This skyscraper was visited in the seventh leg of the reality TV show ''[[The Amazing Race 2]]'', which described Central Plaza as "the tallest building in Hong Kong" (despite this being inaccurate). Although contestants were told to reach the top floor,<ref>{{cite web |title=Hidden in Plain Sight |url=http://www.cbs.com/primetime/amazing_race2/show/episode07/story2.shtml |website=[[CBS News]]|archive-url=https://web.archive.org/web/20020603144302/http://www.cbs.com/primetime/amazing_race2/show/episode07/story2.shtml |archive-date=3 June 2002}}</ref> the actual task was performed on the 46th floor.

==See also==
{{Portal|Hong Kong|Architecture}}

* [[List of tallest buildings in Hong Kong]]
* [[List of buildings and structures in Hong Kong]]
* [[List of tallest freestanding structures]]
{{clear}}

==References==
{{Reflist}}

==External links==
{{commons category|Central Plaza, Hong Kong}}
* {{official website|http://www.centralplaza.com.hk/}}
* [https://archive.today/20090601234410/http://courses.arch.hku.hk/IntgBuildTech/cases/centplaz/centplaz.htm Architectural study of the building]
* [http://www.skyscraperpage.com/diagrams/?c7 Hong Kong's skyscrapers in comparison]
* [https://web.archive.org/web/20090304062222/http://www.hku.hk/bse/bbse2001/lift-example03.gif Central Plaza Elevator Layout]
{{Wan Chai District}}
{{Buildings in Hong Kong timeline}}
{{Hong Kong Skyscrapers}}
{{Supertall skyscrapers | current}}

[[Category:Office buildings completed in 1992]]
[[Category:Skyscraper office buildings in Hong Kong]]
[[Category:Sun Hung Kai Properties]]
[[Category:Wan Chai North]]
[[Category:Ove Arup buildings and structures]]
[[Category:Triangular buildings]]
[[Category:1992 establishments in Hong Kong]]