Investigations on the load bearing behavior of composite dowels in slender webs of ultra-high performance concrete

Ultra-high performance fibre-reinforced concrete (UHPFRC) is now being used more and more in the construction industry. Due to the current development of national and international guidelines and standards, it is to be expected that this trend will continue, and more and more constructions will be realised with this modern building material. This also applies to the field of composite construction. Composite girders with external reinforcement, in which the steel flange lies outside the concrete as a pure tension member, represent an interesting application possibility. The shear-resistant connection between the external reinforcement and the UHPFRC-web, which is as thin as possible, is then made using composite dowels. However, these then only have a very low lateral concrete cover, which is why the determination of the shear load-bearing capacity of composite dowel bars is of particular importance in this case. This present paper describes the results and findings gained from experimental and numerical investigations on Push-out specimens, which were used to investigate the load-bearing and deformation behavior of composite dowels in thin UHPFRC webs. In a follow-up article, proposals for appropriate design models are presented and both the experimental setup and the results of composite beam tests are explained and consequently discussed.