Design of composite dowels as shear connectors according to the German technical approval - Economical Bridge Solutions based on Innovative Composite Dowels and Integrated Abutments - page 46

Figure 1: Application examples for composite dowels [3]

Figure 2: Comparison of longitudinal shear capacity between headed studs and com-

posite dowels (left), comparison of moment capacity and stiffness between
conventional composite section with headed studs and upper flange less steel
section and composite dowels (right)

Up to now, the lack of technical rules for composite dowels led to delays in the approval
process and to retention of clients. However, due to economic and technical advantages in
more and more often composite dowels are used for road and railway bridges in Germany
with approvals in the individual case. For example, the specific prefabricated composite
bridge type VFT-Rail ® with a composite dowel in clothoid strip was approved by the Ger-
man railway authority (EBA) and applied e. g. in the railway bridge Simmerbach, Germany
(“Fig. 3”).
The starting point in the development of composite dowels can be traced back to re-
search of Andrä and Leonhardt, which led to the development of the Perfobond strip [2],
[11]. At the same time Bode developed the Kombidübel [1], [6]. Both design concepts are
based on the mechanical model for shear failure of the concrete dowel. In the following
years important knowledge about the bearing behavior of composite dowels was gained at
the University of German Armed Forces [12], [13]. From this, mechanical models for the
exceedance of the partial area pressure of concrete in the opening and concrete pry-out for
composite dowels next to the concrete surface were obtained. The development of composite
dowels with puzzle strip were pushed by research projects at RWTH Aachen University [8]