Importance of Interlocking Profile Features, and Development of a Unique Australian Steel Deck for Use in Long-spanning Composite Slabs in Concrete-frame Building Construction

Structural steel decking acts as form-work until the concrete reaches sufficient compressive strength for the slab to be loaded. At this stage, modern steel decks are expected to act as effective main reinforcement, and develop significant bond (or longitudinal slip resistance) with the concrete and sustain large axial forces to primarily resist bending effects in the composite slab. High-tensile galvanised steel has historically been used in Australian steel decks, and strong longitudinal slip resistance is required to develop the large tensile capacity of the steel, resulting in significant economic benefits, often eliminating the need for additional bottom steel. Australian concrete-frame building construction is also advanced by international standards with extensive use of steel decking as an alternative to conventional temporary form-work systems. However, these structures are characterised by long-spanning slabs, and if the steel decking is to develop strong longitudinal slip resistance it must have interlocking profile features regularly distributed over its surface designed to prevent the steel from de-laminating. A novel trapezoidal steel deck incorporating distinct interlocking features and complementary corner embossment has been specially developed for use in long-spanning slabs in concrete-frame buildings. The decking ribs are shallow (only 40 mm high), thus minimising their intrusion into a slab soffit. The design of the steel deck is fully explained, and results are presented from composite slab and bond tests that highlight its very strong resistance to de-lamination. In comparison, results of tests on composite slabs incorporating steel decks with poor interlocking features are presented, and important general design advice is given on this topic to assist design engineers.