Civil Engineering Reference
In-Depth Information
tion is assumed at 90 % shear connection. This criterion is applied to evaluate the condition
of the composite joint in cyclic beam tests (acceptable or not acceptable). Afterwards the
condition of the composite joint is correlated with the partial area pressure at the concrete
dowel. Therefore, the partial area pressure ratio E
cd,3D
for upper and lower load from beam
tests are plotted into a Goodman diagram, which is often used for concrete fatigue design
(“Fig. 15” left). Tests with a residual shear connection of more than 90 % are located in the
green area (acceptable), while tests with an unacceptable degradation are plotted outside.
This behavior is shown in “Fig. 15” (middle and right). The strain distribution in test series 7
shows a relatively large strain discontinuity De compared to test series 8, where the loss of
rigid shear connection was not that distinctive. The evaluation of the tests shows that the
available concrete compressive strength under multi axial stress condition is up to 7.5 times
higher than the uniaxial compressive strength. Based on the assumption that at least 10 % of
the total loads are dead loads, the upper load is limited to 55 % of the available multi axial
compression strength.
Figure 14:
Deformation behavior and strain distribution of composite girder with intact
shear connection (left) and damaged shear connection (right)
P
cyc
= 3,1∙
t
w
∙
h
D
∙
f
ck
(11)
Figure 15:
Fatigue strength of cyclic loaded beam tests as a function of partial area pres-
sure ratio
E
cd,3D
for upper and lower load
6. Fabrication and construction
Composite dowels have to be fabricated by gas cutting or a cutting-process, which is similar
in terms of strength and fatigue. The nominal geometrical values are given in Fig. 4, where
tolerances of +2/-4 mm are acceptable (“+” is an enlargement of the steel shape). The cutting
quality has to be in accordance with EN 10901 and EN 10902 and depends on the execution
class. For fatigue loading the quality has to meet the requirements for detail category 125,
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