February_1970 — Page 12

The space requirement was appro- ximately 30,000 sq.ft. and a car park capable of holding 35 cars was also needed.

As the exchange is a protected area, tight security was an essential re- quirement. All walls out of view of the security guard were to be solid, with- out openings, and only one guard- controlled entrance into the car park was called for.

Design concept

The building is situated at the junc- tion of Exeter Road and Devonshire Road. These are two feed roads which link to Orchard Road. As most tele- phone cables in Singapore run below ground along public carriageways, a corner site was of particular advantage, allowing underground cables to enter the building from various directions.

At the earliest stage the architects were instructed to prepare a report on the feasibility of accommodating the board's requirement on this site. The original site was a near rectangular lot of about 20,000 sq.ft. This was subse- quently enlarged to 33,000 sq.ft. by the acquisition of adjoining properties by the board after piling work had been completed.

The restricted site necessitated the design of a compact building, with the car park within it at ground floor. Column spacing at 24ft. centres was found to be suitable for both the car park as well as the telephone equip-

ment.

Heavy exchange equipment is ac- commodated on the three lower floors immediately above the car park, with an area of 12,000 sq.ft. each. The lighter offices are accommodated on the fourth, fifth and sixth floors. The distribution frame room is located on part of the ground floor and has direct connections with the exchange floors above.

Free, uninterrupted floor spaces have been achieved by placing the ver- tical circulation elements such as lifts and staircases in detached vertical towers. Placed in front of the building, the towers also contain toilet facilities at ground, fourth, fifth, sixth and roof levels, and equipment unloading plat- forms at exchange floors. A rear tower contains an escape staircase and rub- bish chute.

The equipment floors, where tight security and strict temperature control are necessary, are enclosed in solid pre- cast wall panels with bands of recessed top lights all round. Fourth and fifth office floors are recessed to shelter from rain and sun and are enclosed with glazed timber walls; these are also shaded by a specially designed alumi- nium sunscreen.

The sixth floor which accom- modates the accounts department, is enclosed with specially designed pre- cast wall units, some of which incor- porate aluminium windows.

During the course of construction, some adjoining properties were acquir ed by the board. It was then decided

that the carpark be moved out of the building and the ground floor used as a sales enquiry area. Certain minor changes of the other areas were also made at this stage.

Superstructure

The building overlies soft ground to about 40ft. depth where a uniform stiff sandy clay layer from 8ft. to 27ft. thick is underlain by sandstone.

The main structure is supported on 14in. x 14in. precast reinforced con- crete piles, 60ft. to 70ft. long, each supporting a working load of 60 tons. Pile caps are integral with the base- ment floor. Boundary walls and other light structures are supported on 40ft. long bakau timber piles.

The main cable trench was cast within steel sheet piles which were left in, and waterproofed by a grouted membrane. The floor was subsequent- ly tested under hydrostatic head of 15ft. and the few damp spots that ap- peared were grouted up.

The superstructure is an in-situ reinforced concrete waffle slab struc- ture with columns at 24ft. centres each way. Precast inverted troughs are used to form floor ribs at 4ft. centres each way. The staircase and lift towers are constructed in in-situ concrete.

Structural depth of the floors is generally 20in. including 11⁄2in. in-situ topping, decreasing at some middle strips to 10in. overall to accommodate air-conditioning ducts. The column heads are 8ft. square and 20in. deep.

14

CAR

PARK

EXETER

R

o

·

B

SALES DEPARTMENT

•

CASHUR

Ground floor plan

GROUND FLOOR PLAN

POVER

MAIN ENTRANCE

W.D.F

DEVONSHIRE

ROAD

Far East BUILDER, February 1970

1st flo