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Edge distance and fastener spacing
If fasteners are placed too close to the concrete
edge, pull-out load capacity will be
reduced. Minimum edge distances are
therefore published with a view to reducing
the effect edges have on pull-out strength.
The corresponding data has been obtained
from tests and analysis and is published in
the product information manual.
The typical edge distance for reinforced
concrete is 80 mm and for non-reinforced
concrete it is 150 mm.
Additional provision is made for fastener
spacing when positioned in pairs or where
fasteners are placed in rows along a concrete
edge.
These edge distances and spacing also
Concrete base material
50 60
Edge distance (mm)
70 80
11 / 2007 1.61
Pullout strength (kN)
8
7
6
5
4
40
3.7 mm shank diameter
B15/55
minimum
have the purpose of helping to prevent concrete
spalling and/or cracking due to fastening.
However, spalling has generally only an
insignificant influence on pull-out strength.
6.3 Effect of time on pull-out resistance
The effect of age on pull-out strength has been investigated in comprehensive tests.
The main concern is, in fact, the effect of concrete relaxation in the area around the driven
fastener.
The graph provides an overview of tests performed
with DX-Kwik fasteners. Since standard
DX fastenings have the same anchoring
mechanism, this statement is also valid
for standard DX fastenings. The test results
indicate very strongly that relaxation of the
concrete has no detrimental effect on the
pull-out resistance of DX fastenings.
The test data also shows that sintering and
keying are the dominant anchorage mechanisms
because they do not rely on friction
between the fastener and the concrete.
Nu,m [kN]
Time [Years]