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 50

therefore a reduction of concrete strength, which causes a secondary concrete pressure fail-
ure. This failure mode is ductile.

(2)

Figure 6: Failure mode pry-out: test specimen (left) and schematic illustration (right)

For composite dowels, where the distance in longitudinal direction is below e x < 4,5 h po ,
the bearing capacity is reduced due to an overlapping of the concrete cones. In this case P po,k
has to be reduced by c x .

(3)

The same effect occurs in the case of parallel arrangement of composite dowels with a
distance smaller than e y < 9 × h po . For this the following reduction factor is used:

(4)

In plate type sections, stirrups ø8 mm have to be used to guarantee for a ductile behavior.
A maximum spacing of 4.5 ∙ h po and 300 mm has to be kept to ensure that at least two rein-
forcing bars are in each concrete cone (“Fig. 7”).
The design against concrete pry-out can be neglected, if the concrete is covered by a
steel flange and confinement stirrups are applied (e. g. beam type sections with external re-
inforcement).