Shear resistance of concrete dowels in composite slim‐floor beams

Abstract

Slim‐floor beams offer the significant advantage of shallow floor depths. When combined with deep profiled steel sheeting, for example, being able to route services in‐between the troughs provides flexibility. Despite their advantages, composite slim‐floor solutions are rarely used in buildings, partly due to the lack of codified rules and detailed design guidelines. One of the objectives of the recently completed, European research project SlimAPP, was to investigate the structural behaviour of slim‐floor composite beams through experimental and numerical studies. Furthermore, design guidance for both the construction and the normal stage was developed. Particular focus was given to the shear connection between the steel section and the concrete slab. As an innovation compared with the conventional use of headed studs, concrete dowel type connectors were considered, where reinforcing bars are passed through openings in the web of the steel section. The findings from push‐out tests and subsequent finite element analyses on concrete dowel connectors are presented. From these results the load resisting mechanisms have been identified. Furthermore, the effect of certain parameters such as the concrete strength, the diameter of the rebar and the size of the web opening on resistance and ductility are evaluated. Analytical models are developed to predict the shear resistance for this type of connectors considering the various load resisting mechanisms. The models are validated against numerical and experimental results from the SlimAPP project and previous research. Comparisons are also presented against results obtained from the back‐analysis of beam tests which were also performed in the SlimAPP project.