October_1967 — Page 12

GEORGE STREET

BOND STREET

SCULPTURE

ப

UPPER PLAZA

VENT

VENT

MACAR PARKING

ENTRY

FOUNTAIN

LOWER PLAZA

LOBBY

PITT STREET

LITTLE GEORGE STREET

0 5 10 20 30 40 50 60

sufficient head room for trucks to drive in and unload within the build- ing adjacent to goods lifts and storage areas. The ventilation to these un- derground floors is by means of two circular shafts extending up above the upper plaza.

A circular form was derived at for the tower building by a process of elimination. Starting with any rec- tangular building of such height and dimension on this site it would be unavoidable to create objectionable "canyon-type" spaces against adjacent buildings which follow the rectangular street pattern. This would result in poor lighting and crowded appear- ance. By placing a square or rec- tangular building on the diagonal much better open space would result in front of the facades.

It was considered that these con- ditions lead logically toward a cir- cular, or as in this case, polygonal- shape, or faceted building which creates ideal space relationships to- ward adjacent properties and allows a maximum of light into surrounding streets. Wide, open spaces result out- side the window facades of such a building which comes close to ad- jacent structures at one tangential point only.

Rigid Contruction

Building regulations were also a contributing factor in arriving at a circular form, which was the only plan shape enabling full development of the allowable floor area of 720,000 sq. ft. for the project. Required set- backs from boundaries to the face of a rectangular building are measured to the average point of a curved building facade. The maximum allow- able rectangular tower plan area of 120 ft. x 100 ft. (12,000 sq. ft.) was thereby extended to a 134 ft. dia- meter with 14,000 sq. ft. of plan area, which coincided with the limit of 25 per cent of the site area.

36

LITTLE GEORGE STREET

51st floor

35th floor

514 ft.

86 ft.

19th floor

Section. Dense concrete is used to 86ft. level.

A circular shape for a very tall building is an ideal form structurally, since it lends itself to very rigid con- struction to resist wind pressures. The core of the building contains the two interlocking "scissor-type" fire stairs, air conditioning ducts, a goods lift and toilets.

Surrounding these are the 17 pas- senger lifts accommodated within an inner and outer concrete shaft extend- ing the full height of the tower. These two tubes of concrete braced by divi- sion walls between the lifts give great rigidity and wind resisting stiffness to

Site plan

the tower simply by their shape, al- though using comparatively little ma- terial.

From this rigid core the floors span without any interior columns to the 20 external columns projecting from the facade. The open free spanning office space is a continuous area of 36 ft. width.

The round form of the building and its circular core of services main- tains the economical ratio of less than 20 per cent for service space to 80 per cent useable office space. This is more favourable than would have

Far East Architect & Builder October, 1967

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