Architect and Builder November/December 2015

WINNER ARCHITECTURAL CATEGORY & WINNER CLADDING CATEGORY: Multichoice City Multichoice City is a large expansion to the east of the current Multichoice/MNET campus on the eastern side of Bram Fischer Drive in Randburg. The primary purpose of the building is for offices and a call centre but the building has been developed as the flagship to the current campus. The judges said that the use of steel played a vital role in emphasising the filigree detail that completes the building. A visitor entering the building is immediately greeted by a grand volumetric atrium space with a wonderfully elegant tubular strutted arch structure supporting air inflated ETFE cushion cladding. The strutted arch spans 24m and its form is ideal for resisting the more dominant uplift wind forces of such a structure, whilst being quite slender in form as a result of the very light (in mass) ETFE cushions. The atrium space is further complemented by beautifully detailed structural steel staircases. The front of the building facing west on Bram Fischer Drive has a very large cantilever ‘peak cap’ roof that cantilevers out towards the street. Structurally, the roof comprises fabricated box girders tapered in sections cantilevering generally 12m (maximum cantilever being 13.5m). The closed box form is further stabilised by a tubular bracing network ensuring, despite the large cantilever, that the structure remains stable. The back edge of the roof allows free flow of wind under it to ensure wind uplift forces are minimised. Also facing Bram Fischer Drive is a ‘jelly bean’ shaped portion of the building which is clad in active glass louvres that open and close automatically to shade the interior from the late afternoon sun whilst leaving uninterrupted views for most of the day. Tubular steel arms cantilever out from the slab behind to support a curvilinear tubular member that supports the glass louvres and mechanical actuators. The project team said that the early involvement of the two steelwork contractors played a major role in achieving the end result. The judges said that the mechanised glass louvres, ETFE cushion roof and dramatic cantilever ‘peak cap’ roof, along with all the other filigree steelwork, go a long way towards achieving the architect’s vision for a crisp, modern and elegant office. “A practical and beautiful structure thoroughly deserving this award,” they concluded. Steel Awards Cladding: The underslung cladding to the ‘peak cap’ feature on Multichoice City, winner of the Global Roofing Solutions Cladding category, must be one of the most visible cladding solutions in SA. The judges said that this project was a clear winner. “Hanging underslung cladding is a process not for the fainthearted. It is exceptionally difficult to do well, especially with the hidden fixing type cladding used on this project,” they said. The cladding is to a 12m cantilever which follows its structural shape requirements tapering from width at the support end to a narrow tip. The project team said that the installation procedure was a challenge due to the length of the sheet and the fact that the und \

Architect and Builder November/December 2015 | Page 65