A composite floor truss top chord using concrete-filled steel tube (CFST)

Abstract

Steel and concrete composite systems are generally used as major structural components in multi-storey buildings. Steel decking is a more common composite system in buildings since it serves as a working platform to support the construction loads and also acts as a permanent formwork for concrete. To achieve large column-free spans (in the range of 8m-12m), as often demanded in multi-storey office buildings, steel and concrete composite floor trusses may form economical solutions since they are able 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 with 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 covers and the effect of different concrete strengths were investigated and the results compared with existing guidelines for headed shear studs.