Construction World November 2015

PROJECT PROFILE

2015 WINNERS

Winner – architectural 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. 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 24 metres 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 beau- tifully detailed structural steel staircases. Structurally the roof comprises fabricated box girders tapered in section cantilevering generally 12 metres (maximum cantilever being 13,5 metres). 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.

STEEL AWARDS

LSFB category commendation: Kuruman Casino Façade The judges commented that local architects and engineers have in the last few years recognised the insulating values and architec- tural flexibility offered by the Light Steel Frame Building (LSFB) and External Thermal Insulation Composite System (ETICS) systems. The 300 m² Kuruman Casino facade is supported on a light steel framed structure which was factory built. Sheathing comprising OSB board was fixed to the frame and covered by a vapour permeable membrane which was in turn fixed to the sheathing, followed by EPS insulation boards. The EPS board was then primed and sealed with a decorative acrylic resin topcoat. The external insulation results in a ‘warm frame’ which prevents condensation on the steel frame adding to the durability of the structure.

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Winner – mining and industrial category: Medupi Power Station-Air Cooled Condenser In 2007, GEA approached A. Leita and Kentz to submit a bid for the Medupi air cooling structures, some 26 000 tons of steel. Leita teamed up with Cadcon and Boksan Projects and formed the ABC Joint Venture with Leita leading the fabrication team with Kentz doing the on-site work. According to the judges, when one visits the site, because of the enormous boiler houses which stand close to the air cooling units, one is surprised to learn that each unit has over 4 000 tons of steelwork. “To grasp just how big a project the air cooling actually is, it was necessary for us to drill down into what makes these units tick,” they said. There is an air cooling unit for each of the six boilers; the radiators sit on a structural steel support structure; floor beams are covered with 4 mm floor plates; an A-frame structure is fabricated out of heavy H beams; and the fan bridges span between the main girders.

CONSTRUCTION WORLD NOVEMBER 2015