Title: Development of a Novel Concrete Walling System using Permanent Steel Formwork Panels

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Publication: CIA

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Date: 2/13/2011

Abstract:
Conventional steel decking was introduced into Australia approximately 40 years ago as a dual formwork and reinforcement system primarily to construct one-way slabs supported on steel beams in steelframe buildings. Owing to recent significant advances in the level of understanding about its structural behaviour in hardened concrete, it is now confidently used to construct many types of floors in concrete-frame buildings. A unique steel formwork system comprising ultra long-spanning cellular panels has been developed, and has been used in the construction of slabs up to 600 mm deep. This system has recently been adapted to construct vertical ground-retaining walls in excess of 6 metres high, where the wet concrete pressures can be very much larger, utilising the exceptionally high strength of the panels. Ground pressure on the final concrete wall can also be very high, requiring careful design. A temporary shoring system allows the light steel panels to be preassembled manually on site into wide wall panel modules, which are lifted vertically into position around the excavation boundary and propped. Full-scale laboratory testing validated the design of critical connections. The wall panels acted as vertical formwork and were transversely reinforced for crack control. The sequence of pour lifts is synchronized with the set-time of the concrete, partial removal of the temporary propping system, and construction of the final structure within the confines of the excavation.