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Steel base material
Fasteners tested
The primary fastener used in the tests was the Hilti ENP3-21 L15, the predecessor of the
ENP2-21 L15. The difference is in the head shape, which has no effect on interaction with
the base steel. Tests were also performed with the ENP2-21 L15, ENP3-21 D12 and the
EM8-11-14 threaded stud, all of which have 4.5 mm diameter knurled shanks.
ENP3-21 L15 ENP2-21 L15 ENP3-21 D12 EM8-11-14 P8
The data has now been replotted
in S-N curves with
stress range as the independent
variable. The purpose of
comparison, the AWS-C,
AWS-D, AWS-E and AWS-
DEn F2 as well as EC3-90
and EC3-100/m = 5 curves
have been plotted in all the
diagrams. There are 22 S-N
diagrams for St 37 (similar to
A36) and 36 for St 52 (similar
to A572 Grade 50). An example
with stress ratio R = 0.5 is
shown in following S-N
graph.
Stress Range [ksi]
Effekt of Hilti PAFs on Fatigue Strength of Structural Steel
Comparison of Fatigue Test Data with AWS S-N curves
Cycle Life
Conclusions
• The effect of driving a power-actuated fastener into structural steel is predictable.
• The effect of power-actuated fasteners on the fatigue strength of steel is well known.
In comparison with most weld details, power-actuated fasteners have a smaller stress concentration
effect. This is shown by the fact that all power-actuated fastener results were
above the AWS category C curve.
• Fatigue curves according to Eurocode 3 allow fatigue design of steel members in which
power-actuated fasteners have been driven.
1.54 11 / 2007
Stress Range [N/mm 2 ]