Civil Engineering March 2021 | Vol 29 No 2

Civil Engineering March 2021 45 WINNER IN THE ASTPM TUBULAR CATEGORY Menlyn Maine West Atrium Skylight Park Lane West is a new premium grade commercial development in Menlyn, Pretoria. At the centre of the 7-storey building there is a 26 m × 17 m atrium skylight which brings natural light into the building. The architectural brief was to create a modern skylight, with lightweight steel members and a very clean geometry, that would bring the right balance of heat and light into the atrium below. Due to the need for a lightweight structure that could support large glass lites, steel was the obviously material of choice. Structural Framing Rectangular hollow sections were selected for the main beam to concealed connec- tions. In addition, since the structure was designed as a braced three-pin pitched roof, the hollow sections efficiently car- ried the bending and compression forces. Small diameter round tubes were used for longitudinal apex bracing. Due to the accuracy of the steelwork and efficiency of the glazing installation team, up to 16 glass panels could be installed in one day – this equates to the weight of the full steel structure in glass panels per day. To reduce the number of steel beams, large point supported glass panels were used. Each panel was 2.2 m × 3.3 m and weighed approximately 350 kg. Challenges Since all the glass lites were fully tem- pered and prefabricated, the steelwork needed to be installed to a very high degree of tolerance to ensure each glass lite would fit. Extensive QAQC checks were carried out both in the factory and on site before the cladding was installed. The benefits of steel The high yield strength of the S355 tubes enabled small beams to be used, while the hollow sections enabled neat hidden connection details. In addition, due to the stringent deflection requirements of the glass, both during installation and over the long term, the high stiff- ness of the structure enables the joints between each glass panel to be sealed with a neat strip of silicone. No mullions were required. Once completed, the low pitch ridged roof, consisting of neatly fabricated hollow steel sections and large glass panels, created a simple but bespoke looking skylight.  KEY PLAYERS Client/Developer Menlyn Maine Architect Boogertman and Partners Structural engineer LEAF Structures Main contractor Barrow Construction Steelwork contractor Tass Engineering Cladding manufacturer & contractor LEAF Structures