PwC Tower is PwC’s new head office in Johannesburg. The floor plates of the 28-storey building rotate by 1.2 degrees per floor, which results in a doubly-curved surface for the building’s façade and the structural line behind. The reception is housed in a triple volume lobby area at ground floor. This triple volume space flows into the adjacent meeting centre, and is used as a café and informal meeting space.
A steel and glass atrium roof covers the link between the tower and the meeting centre, whilst a steel link bridge with glazed balustrades connects the two floors at first floor level with a steel feature stair forming the principal link up to the second floor of the meeting centre. Whilst the majority of the tower floors are post-tensioned concrete, the first and second floors of the tower are formed in steelwork with bondek slabs and are hung from the third floor, to increase the column-free space in the lobby below. The northern part of the lobby features a triple volume steel and glass façade, gently following the twist of the tower. Within the atrium and outside the glass façade the sloping and spiralling columns of the building are encased in steel tubes to act compositely with the concrete inside; this increases the capacity of the reinforced concrete columns where they are unrestrained over the three floors and means that the overall section sizes can be similar to the rest of the tower which allows us to achieve the preferred architectural aesthetic. All of these components feature the use of steelwork in a complex geometric form and in the majority of cases the painted steel is exposed to form the finished surface.
Rectangular hollow sections were used on the skylight. The suspended floors were built out of BOND-DEK on cellular beams, with curved edge beams rolled horizontally. The hangers are circular hollow profiles. The bridge and stair are predominantly formed from welded plate with concealed connections and preformed slots for the cantilevered glazed balustrades. The façade mullions, spanning over three floors are I-sections, and are laterally restrained by circular hollow profiles. Rolled square hollow profiles are used over the main entrance doors. The structural columns in the tower are encased in large diameter circular hollow tubes.
The geometry of all this steelwork was generated by parametric scripts. The steel profiles were explicitly modelled in 3D by the design team. Conventional plans with all setting out information were produced for use on site but the 3D steelwork model was also issued to the contractor to use as the basis of their steel shop model and then later used to check the steel shop model.
|Tons of structural steel used||250t|
|Structural profiles used||RHS, CHS, UB, UC and plates|
|Project Team Role||Company|
|Quantity Surveyor||Brian Heineberg & Associates|
|Cladding Manufacturer||Geustyn & Horak (G&H Aluminium)|
|Cladding Supplier||Geustyn & Horak (G&H Aluminium)|
|Cladding Contractor||Geustyn & Horak (G&H Aluminium)|
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