2018 SAPOA Awards | Page 15

CORPORATE DEVELOPMENTS: WINNER PwC Tower, Waterfall City, Johannesburg The new head office for PwC at Waterfall City is an iconic addition to the Johannesburg skyline. The tallest structure by far in the Waterfall and Midrand area, the building is home to 3,500 employees in over 47,000m 2 of ultramodern offices. Its distinctive twisting façade is an expression of innovative architectural and structural collaboration in creating a world class building. The construction process saw the core of the structure going up first to the full height of the building, prompting curious early onlookers to ask the question, why is the building so thin? It was only once the rest of the floor space on each storey was added from the bottom up, that a fuller picture emerged of the silhouette of this eye- catching building, with its dramatic twist design. The core of the building was constructed using a method called slip forming, where the concrete is poured continuously within the steel shutters. By erecting the core in one operation early in the project, it speeds up construction of the rest of the building, since you can then just build the floors and columns, rather than waiting for construction of the walls. Internationally this method is relatively common for buildings over ten storeys, but in South Africa it has most recently only been used for forming chimneys and cooling towers. The spiralling geometry of the building creates unusual forces on the tower. Rather than putting all of this load on the central core which would be very inefficient, the columns were sloped along the façade of the building in the opposite direction. This generates two twisting forces, SAPOA Awards which cancel each other out. The structural engineers reviewed many iterations to get the optimal balance and to ensure that this was closely coordinated with the overall geometry and the façade design. The unique façade of the building creates a striking first impression. The 3D geometry and unique aluminium profiles. The frames are warped to accommodate the twisting imposed by the rotation of each floor relative to the floor below. Arup believes that this is the first curtain wall in South Africa with twisted unitised panels. The building is designed to conform to the internationally recognised LEED Silver Standard rating, emphasising its environmental performance and sustainable design. The tower is connected, social and dynamic in form and arrangement of spaces, with occupiers benefiting from its proximity to a 1.2 hectare park, the Mall of Africa and several residential areas. The PWC Tower is a worthy inclusion among the best spiral buildings in the world. Developer: Attacq; Atterbury Owner: Attacq Architects & Project Managers: LYT Architecture Quantity Surveyors: Brian Heineberg & Associates Civil & Structural Engineers: Arup Electrical Engineers: Claassen Auret Mechanical Engineers: WSP Green Consultants: Ecocentric Fire Consultant: SFT Main Contractor: WBHO Construction 71