Influencing parameters on the load-bearing behaviour of composite dowels positioned close to the free surface of concrete slabs

Abstract

Composite dowels are an economic alternative to headed studs, the conventional shear connectors. Modern concrete slabs are dimensioned increasingly thinner and often include several additional functions. For those applications, composite dowels can be positioned horizontally in the concrete slab leading to a small space between the dowel and the free concrete surface. Existing investigations on composite dowels describe different failure modes such as splitting of the concrete, pry-out of a concrete cone or plasticizing of the steel. At University of Kaiserslautern composite dowels with positions close to the free surface of the concrete slab were investigated experimentally by push-out-tests within a joint research project with RWTH Aachen. In the process further failure mechanisms were inspected which are not covered by the existing design approach for conventional positioned composite dowels (in sufficient distance from free concrete surfaces). Within this paper, the influence of the parameters concrete strength, slab thickness and reinforcement position are presented.