Composite one-way concrete slabs with profiled steel decking as permanent formwork are commonly used in the construction industry. The steel decking supports the wet concrete of a cast in situ reinforced or post-tensioned concrete slab and, after the concrete sets, acts as external reinforcement. In this type of slab, longitudinal shear failure between the concrete and the steel decking is the most common type of failure at the ultimate load stage. Design codes require the experimental evaluation of the ultimate load capacity and longitudinal shear strength of each type of steel decking using full-scale tests on simple-span slabs. There is also no procedure in current design codes to evaluate the ultimate load capacity and longitudinal shear strength of continuous composite slabs and this is often assessed experimentally by full-scale tests. This paper presents the results of three full-scale tests up to failure on continuous composite concrete slabs cast with trapezoidal steel decking profile (KF70) that is widely used in Australia. Slab specimens were tested in four-point bending at each span with shear spans of span/4. The longitudinal shear failure of each slab is evaluated and the measured mid-span deflection, the end slip and the mid-span steel and concrete strains are also presented and discussed. Redistribution of bending moment in each slab is presented and discussed. A finite element model is proposed and verified by experimental data using interface element to model the bond properties between steel decking and concrete slab and investigate the ultimate strength of continuous composite concrete slabs.