BANKING CORPORATION HEADQUARTERS, HONG KONG

The building has four basement levels and 43 storeys above ground to the top of the highest steel masts, with a helipad structure rising above this giving the building an overall height of 179 m. The structure consists of only eight masts, some of which are visible on elevation. The masts consist of four round vertical tubes and plan cross-bracing connecting them together at the storey-height intervals of 3.90 m. There are four lines of masts running in the east-west direction, the two masts on each line supporting, at intervals in the building's height, a pair of double-storey height suspension trusses which span 33.60 m between the masts and cantilever 10.80 m beyond them. In the three bay areas between the outer column lines, the floors terminate at levels 30, 37 and 43 in the south, north and central bays respectively. There are suspension trusses at all these three levels, as well as further down at levels 11 and 20. The trusses effectively divide the building over its height into five independent structures.

The floors in each of these five horizontal zones are supported by vertical hangers attached to the suspension trusses above. All the trusses have a similar form but the trusses on the exposed north and south faces do not have the top boom in the central span that is included in the others. At the suspension truss levels, the masts are also connected in the north-south direction, at each side of the building by cross-bracing two-storey high running on the inner line of the mast tubes only. Three-storey high cross-bracing, in the same plan position, is provided across the two central columns of the atrium between levels 5 and 8. The floor structure consists of 900 mm deep plate girder primary beams in the east-west direction running along the mast tube lines, supported between the masts and the hangers. These support secondary beams at 2.40 m centres which support 54 mm deep metal decks with 100 mm of concrete topping. Each mast is taken down to the lowest basement level where it is supported, vertically, by four 3 m diameter caissons taken to rock, one under each leg. Horizontal support is provided by the basement floor structure one level below ground. The masts, suspension trusses, hangers and any other exposed or important elements are given corrosion protection by a 12 mm thick sprayed cement coat containing a polymer additive and 5% by weight of stainless steel fibres.

The external skin of the building consists of aluminium cladding and mainly glass curtain walls and is unusually complex. All visible structural elements are clad. There are four main types of cladding. The first type, for office areas, is a glass curtain wall, seen particularly on the north and south elevations. It comprises aluminium mullions at 1.20 m centres with sill rails at storey heights into which are fixed 12 mm thick toughened (tempered) glass sheets. A steel T-section anchor, attached to the floor through vertically slotted holes and to an aluminium bracket with horizontally slotted holes, allows the aluminium bracket, which supports the sill and mullions to be precisely positioned. The glazing, therefore, only needs to allow for tolerances.

An inner wall of lightly tinted glass is provided inside the external glazing. A horizontal joint at each storey allows for floor deflections and thermal movements. The second type of cladding consists of glass panels in a metal grid cladding the stairs on the east and west sides. The panel size is 2.40 m wide by a storey height consisting of four panes of 12 mm toughened (tempered) glass attached to the aluminium sub-frame by a structural silicon sealant. The third type consists of laminated panels of the same size, for the service modules and ‘risers’ (здесь - ступени) on the east and west sides. The panel is 25 mm thick and consists of aluminium sheets. The panel is glued and riveted to an aluminium sub-frame which interlocks with adjacent panels. The fourth type consists of the curved and flat sheet metal panels which clad the structure; they are 6mm thick aluminium sheets welded to aluminium edge sections.

Notes:

atrium n. атриум

helipad n. вертолётная площадка

pane n. оконное стекло

plate girder primary beam стальная составная основная балка

rivet v. заклёпывать

service module инженерный отсек

silicon sealant силиконовый герметик

sill rail нижняя направляющая остекления

sub-frame n. обрешетина (под облицовку)

suspension truss висячая ферма

T section однотаврового сечения/ Т-образного сечения

Ответьте на вопросы к тексту

1. What does the structure consist of?

2. What is a mast made of?

3. How is each mast support provided?

4. How do suspension trusses function?

5. What does the floor structure consist of?

6. How are important elements of the building protected against corrosion?

7. What makes the external skin of the building unusually complex?

8. How are office areas clad?

9. What does the cladding of the stairs on the east and west sides feature?

10. How are the service modules and ‘risers’ clad?

11. What is the fourth type of cladding?