International Commerce Center, Hong Kong
ICC totes up to skyline of Hong Kong
Hong Kong's skyline is considered one of the best in the world with its several tall structures around. One among the skyline is the International Commerce Center flanged by its appearance among the other structures in the surrounding region of the harbor area. Designed by Kohn Pedersen Fox of New York, the structure has excellently created an iconic image in the city of Hong Kong. At 118-storeys, International Commerce Centre (ICC), the newly completed mixed-use tower is the fourth tallest in the world and will redefine one of its most famous skylines. Rising 490 meters high from the peninsula of West Kowloon, the emergence of ICC reflects the rapidly developing financial district.
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It also works as a gateway into Hong Kong, along with the complementary International Finance Centre across the harbor. This shimmering tower serves as a beacon to the Hong Kong Harbor, creating the perfect gateway with its counterpart, 2 IFC. The way in which the scaled façade sweeps outward at the base into a grand canopy is beautiful and creates a strong relationship with the rest of the Kowloon Station Development. The building is an elegant silhouette and will be the fourth tallest in the world. Sited above Kowloon Station, ICC is integrated with a public transportation infrastructure that carries 11 million passenger journeys per day (Hong Kong Special Administrative Region 2009). ICC’s success as a development stems from is its seamless connections with Central, Hong Kong International Airport, and mainland China via a network of high-speed rail, subway, buses, and ferry terminals.
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Super Skyscraper
KPF won the commission to design ICC through an invited competition in 2000. For the competition entry, a partnership was formed with Leslie E. Robertson Associates to create a tower form that would combine the best possible structure with the best possible floor plate. For instance, a tower geometry based on a circular floor plate would perform well in the wind, but would be undesirable to Hong Kong's financial tenants, who prefer the efficient layout of square floors. Conversely, a perfectly square floor plate would perform poorly in the wind and lead to an increase in steel and concrete an unsustainable proposition. An analysis of preliminary wind tunnel studies indicated that a square with notched, or "re-entrant," corners would exhibit nearly the same wind response as that of a circle. The building is also designed to combine the best possible structure with the most efficient floor plate.
From this initial form, the massing was refined by gradually widening the re-entrant corners towards the top and inclining the upper third of the main façades by one degree to create the tower's elegant silhouette and improve its wind response. The tower's eight mega-columns splay out three degrees to widen the tower's dimension at its base, significantly reducing the tower's overturning moment, while providing longer clear spans for hotel and exhibition facilities. Design Principal William Pedersen sculpted the tower's curtain wall into a series of overlapping panels, each one-story high, which he likened to shingles on a roof or the scales of a dragon. The shingled curtain wall generates a kaleidoscopic play of light and shadow, as it mirrors different parts of the sky, de-materializing the tower's immense mass while relating to the viewer through the repetition of tangible human-scale elements.
Reminiscent Scales
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The architect collaborated with the façade engineers at ALT Cladding Consultants to break down the apparent complexity of the curtain wall system into a few highly repetitive components. Each shingled panel is rotated exactly five degrees with respect to the "smooth" geometric surface, yielding just three wall types consisting of 5, 6, and 8 degree panels from the base to the top. The catenary, or curve, of the dragon tail was approximated by three tangential arc segments of varying radii that, when subdivided, yielded panels of equal dimension which were similarly rotated five degrees from the defining geometry. According to Permasteelisa, who fabricated and installed the curtain wall, three-quarters of the total façade area was built up from only 134 panel types. Design Principal William Pedersen sculpted the tower's curtain wall into a series of overlapping panels, each one-story high, which he likened to shingles on a roof or the scales of a dragon. The shingled curtain wall generates a kaleidoscopic play of light and shadow, as it mirrors different parts of the sky, de-materializing the tower’s immense mass while relating to the viewer through the repetition of tangible human-scale elements. Viewed from below, the serrated profile formed by the underside of the shingled panels gives the impression of the building skin breathing like a giant bellows.
The Core
The ICC tower relies on a reinforced-concrete central core and an eight-mega-column structure for its square-donut plan, proposed by the structural engineer for the conceptual design. Outrigger trusses couple the central core to the mega-columns on four different floors in the tower, with the lowest one made of pre stressed concrete and the others constructed of structural steel. To deal with the soil and, below that, a cliff like bedrock, structural engineers for the execution of ICC, ARUP, turned to shaft-grouted friction barrettes for the foundation. As ARUP director Philip Lai explains, the barrettes rectangular concrete piles, with an average depth of 230 feet transfer loads on four sides to adjacent soil for stability. The lanky structure is constructed with 76m diameter cofferdam lined with 1.5m thick diaphragm wall panels was formed to facilitate the construction of the 9m deep foundation raft and core wall structure of tower using bottom up arrangement. Basement in 2 levels is constructed using semi bottom-up arrangement due to limited space and the existence of the MTR tunnel tube crossing within 6m on the side of the tower foot-print. Grade 90 concrete is used up to 60th floor.
Concrete Challenges
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Standing at 484 meters, and slated to be the fourth tallest building in the world, the ICC requires ultra high strength concrete of up to 90Mpa to support its massive structure. This concrete needs to be pumped up to over 400 metres, and have self-consolidating qualities to flow through highly congested steel formwork. Furthermore, the concrete for the foundation must have excellent slump retention for the pours down very deep bore piles. Hong Kong has never witnessed a development project of this scale and height and consequently, concrete solutions for this project were as yet untested. Grace also supplied MIRA RT69, a mid-range water reducer, used in developing tremie concrete mix for foundation work. Designed to provide concrete with extended slump life, superior water reduction and controlled retardation, MIRA RT69 was primarily chosen because of its excellent slump retention. This enabled the concrete to be poured into very deep bore piles and to maintain its workability and slump for five hours, the duration of each placement operation at the jobsite.
Fireproofing Challenges
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Additionally, the ICC has a tight fireproofing application cycle on each floor, for all steel beams and columns. With conventional fireproofing technology, meeting this tight schedule can be challenging, as every layer of fireproofing material, which can be only applied at approximately 15-18 mm thickness, requires four to six hours to set before subsequent layers can be sprayed.
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Hoists
Six Alimak construction hoists were being used to reduce tower crane lifting duties on the 118-story International Commerce Center. Three Alimak dual construction hoists with a total of six cars are being used for the transportation of personnel and materials during the construction. Alimak Hek has supplied a three-unit hoist configuration with each unit having two cars, for a total of six cars. The installation includes two of the largest cars the company has ever installed on a single mast, both measuring 2 m x 5 m. The hoists have been installed on a common tower secured to the front of the ICC building, which is part of the Union Square multi-tower complex. Each of the three units operates on its own mast attached to the common tower. In addition to the building materials, the hoists are also used to transport large numbers of the 2,000-plus working personnel to the various levels of the building. The two largest cars are part of an Alimak Scando Super FC 33/50C TD dual-car hoist. Two Alimak Scando Super FC 28/27 C TD dual-car hoists provide another four cars in total, each of them measuring 1.5 m x 3.7 m in car size.
Apart from facing extreme challenges during the tenure of construction, this lanky structure has made a fresh statement in the skyline of Hong Kong. Moreover it was christened as the fourth tallest structure in the world among the other rulers of the sky and most importantly the sparkling façade on the structure will attract the onlookers travelling to the city through sea. Thus this dazzling structure situated closer to the sea port of Hong Kong is the new landmark and enchantment of the city.
Box Item:
- Gross floor area: from 31,182 sq ft to 38,864
- Span from core to façade: from 11.76m to 17.30m
- Floor to ceiling height:2.85m in zone 1 & 2, and 3.15m for zone 3 to 5
- Raised floor for typical floor: 150mm
- Double glazed with low E-coating curtain wall
- Thirty 21-person local passenger lifts in 5 zones, fourteen shuttle lifts to high zones and two VIP lifts
- Dual power supply feed
- 80 VA/m2 load distribution for typical floor
- 20 VA/m2 standby generators for essential back-up power on typical floor
- Twelve generators for essential chiller back-up, tenants' essential supply and fire services
- VAV ceiling ducted system with intellegent Direct Digital Control via BMS
- 24-hr chilled water supply with generator back up
- Dual tenant risers for power, telephone and data
- Wireless aerial provision for mobile phones in premises' ceiling, lifts and common areas
- Aerial broadcast and satellite TV receptions
- 24-hr access and security control systems
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