SKYLIGHT CONSTRUCTION REPORT At the centre of the Mall there is a 4,300m 2 undulating, free-form skylight, running 170m in the north-south direction. Novum Structures was appointed as the design-build specialist sub-contractor for the design and installation of the skylight. Aurecon designed the perimeter concrete support structure.
Design Overview The 3D surface and grid development of the skylight was a multi-stepped iteractive process which aimed to balance the overall architectural intent, the spanning capacity of the cladding, drainage, cost and other structural considerations. To create a single-layer steel structure, the overall skylight was designed as three independent thrusting skylights, separated by two building expansion joints.
The structural design was carried out using the direct design method, considering both local and global imperfections and considering lateral movements in the perimeter concrete upstand beams. Due to the large spans at the central region of the skylight, tree columns were added to ensure that the same overall rectangular tube sizes could be used throughout the skylight.
Logistics A combination of 1,352 unique rectangular steel beams with custom end castings and 577 machined nodes were used to create the free form structural grid. To increase the accuracy and speed of installation, the beams were site-bolted to the disk-shaped nodes using the Novum FFsystem.
The cladding consists of 1,352 unique aluminium extrusions which support 846 ETFE pillows. In order to efficiently manage the fabrication, transportation and installation of these components, each part was marked with a unique number and the orientation was stipulated in the installation drawings. The structure and cladding were fabricated by a combination of various in-house Novum entities and local suppliers. Due to site constraints, materials were stored off-site and delivered to site as required to meet the installation sequence.
Steel Installation The steelwork for the skylight was installed using a combination of a self-erecting crane standing on the level three slab and an eight-ton mobile crane on the level five slab. The structure was assembled by lifting pre-bolted three-arm spider
38 Mall of Africa