Longitudinal shear stress and bond–slip relationships in composite concrete slabs

• Short term test results in eight composite slabs using four profiles are presented.
• The slabs were tested with shear spans of either L′/4 or L′/6.
• The measured bond–slip relationship of each slab is presented.
• A finite element model utilizing interface element to model bond property is used.
• The numerical model is shown to reliably predict the measured responses of the slabs.

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 longitudinal shear capacity of each type of steel decking using full scale tests.This paper presents the results of the short term testing up to failure of four types of profiled decking that are widely used in Australia. Full-scale, simply-supported slab specimens were tested in four-point bending with shear spans of either span/4 or span/6. The bond–slip relationship of each slab was determined during the testing and the values of maximum longitudinal shear stress calculated using different methods are described and compared. 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 composite slabs.