November_1970 — Page 17

ed cost of constructing this building is said to set favourably against both rein- forced concrete and precast pre-ten- sioned structures.

Flexible space

The Ngau Tau Kok building is a polyclinic and social welfare centre built with funds provided by social welfare organisations and a donation from the HK Government Lottery Fund. An advantage of using prestress- ed construction was that it provided a completely column-free interior space which may be flexibly utilised as needs change.

Elevator and stair core walls are located at the two ends of the building to resist laterial loads. Between these, 48 ft. span post-tensioned 14 in. x 27.5 in. beams form a six-storey single bay rigid frame. The beams, are spaced at 20 ft. centre to centre with a 6 in. post-tensioned continuous floor slab spanning between them.

The floors are designed for a 100 lb. per sq. ft. live load, including parti- tions. Post-tensioned tendons required in the slab amount to only 0.75 lb. per sq. ft. and there is no mild steel in the slab.

Shear walls above the roof level are connected by reinforced concrete vierendeel trusses with precast roof channels for the upper roof.

A further advantage of this type of structure is the saving in raw materials and labour. Normally too there is a saving in construction time, though at the time of design for this particular building (1967), no unbonded tendons for floor slabs were available in Hong Kong and the tendons had to be fabri- cated on the erected formwork, which caused some delay.

Fair face

On the finished building the two lift and stair towers are left fair-faced, the rectangular formwork and uniform. placing of the tie-pins being clearly marked. To contrast with these the side walls are finished in Shanghai plaster with the framework emphasis- ed in bands of grey. From third floor to sixth floor levels, six vertical sun- breakers between columns protect narrow window units.

The welfare centre/clinic provides a service to the 100,000 refugees from mainland China living in high density resettlement estates in the Ngau Tau Kok area. It accommodates a day nursery and kindergarten, club, recrea- tion and handicraft rooms and library

Far East BUILDER, November 1970 Page 17

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Section

for youth groups, classrooms for voca- tional training, a community hall and district social workers offices. The clinic has a dental surgery and consult- ing rooms for three doctors and nurses, a pharmacy and a small labora- tory.

The total cost of the building, ex- professional fees. was

cluding

ROOF

6TH

FL

STH FL

4TH FL

JRO

FL.

2ND FL.

UPPER LIST FL

IST FL.

GAD FL.

Detail of fairface stair tower

HK$1,125,467. This total was made up as follows: Site formation building

HK$ 6,967 920,000

plumbing and sanitary fitments 50,000 electrical wiring and installation 50,000 fire service installation elevators

7,300 91,200 1,125,467

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