Innovative Floor Truss Top Chord for Achieving Long Spans

Steel and concrete composite systems are generally used as major structural components in multi-storey buildings. Composite construction in buildings is more popular with steel decking since it serves as a working platform to support the construction loads and also as permanent formwork for concrete. To achieve large column free spans (in the range of 8m-12m), as often demanded for multistorey office buildings, "steel and concrete composite floor trusses" may form economical solutions since they provide the facility to accommodate various service ducts within the structural zone. The concept of introducing a concrete filled steel tube (CFST), instead of the conventional open flanged steel section, as the top chord of these floor trusses has been discussed. However, the viability of this new concept should be ensured by experimental evidence on the longitudinal shear transfer capacity at the composite stage. This paper discusses the experimental results of a series of push-off tests conducted on CFST embedded composite slab panels. The effect of providing different concrete top cover and effect of different concrete strength have been investigated, and the results are compared with existing practice related to headed shear studs.