July_1971 — Page 18

Fint B

O

Flat A

Typical floor plan

a severe shortage of flats, the super- structure contract was negotiated on a cost plus basis with the same contractor to take full advantage of the overlap between sub-structure and super-structure contracts.

The tower super-structure which controlled the critial path, was thus started while the site formation and approach road were still being formed. The entire building was completed on 25th May, 1971.

Structurally, the building may be considered as three separate structural

Exit to pool area

T

Cross section

units: (a) the 35-storey tower; (b) the 3-storey podium; and (c) the swimm- ing pool structure. The podium and pool structures are separated from the tower by an expansion joint.

The tower structure consists essen- tially of a system of flat plate floor slabs spanning between the central core and the outer spandrel beam. Gravity loads are taken by the core and columns, while the lateral loads from wind are resisted by the combin- ed action of core, slab and the beam/ column frame system.

It was considered that a building of this magnitude and slender propor tions should not be designed to take typhoon force winds with the core only. A more elaborate elastic analysis was therefore carried out to achieve an optimum solution with maximum structural economy.

The basic wind pressures conform with the requirements of the Hong Kong Building Ordinance Office Build- ing Construction Regulations, but the shape factor has been increased from 0.65 to 0.8 to allow for eddies and buffeting from hills and possible fu- ture development in the area.

The stiffness analysis of the system as a whole was carried out in the fol- lowing steps: -

An investigation was made of the bending rigidity of the annular floor slabs. Solutions to the differential equation of bending of an annular plate when subjected to a moment applied at the centre were found for differing boundary conditions. From the known rigidity of the slabs these were replaced, for the purpose of the analysis, with "connecting beams" of like properties.

Hence the structure was reduced to a shear wall and coupled frame. By determining the wall slope at each floor level design moments and shears could be found throughout.

It was found that 60 per cent of the total wind loading was resisted by frame action, leaving 40 per cent to be taken by the shear core. In order to allow for some latitude the core and

Far East BUILDER, July 1971

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