User Guide

6
LET’S GO ON-SITE AND DISCUSS A FEW SCENARIOS
Scenario A
(a
1
) Anchors approved for masonry installed in a non-standard masonry brick
(a
2
) Anchor or a post-installed rebar approved for concrete to be installed in
concrete where the concrete strength class is not known.
Is that the right scenario for Hilti on-site testing?
The answer is a clear “yes”
Why?
No technical data for the design of the anchor is available or the technical data for the
specific fastening solution is incomplete. This is based on the fact that – as
mentioned above – the base material is not sufficiently well known and not covered
adequately by an approval but it’s within the category (similarity) and therefore
comparable with the base material of the approval.
Why is the “similarity” of the base material so important?
We know very well the influencing parameter on the concrete cone failure load of
anchors anchored in normal weight concrete or masonry. The main parameters for
concrete cone failure are embedment depth (h
ef
) and concrete compressive strength
(f
c
). However, we have no indication how an anchor performs in a base material like
ice or butter. Even if the on-site testing would give us “results” we are still not able to
design, because we do not know the decisive parameters on the failure load,
consequently the base material should be similar to the one in the scope of the
approval
Necessary information or questions which should be stated for Scenario A:
Is the structure sensitive to possible damage or are there other architectural
appearance issues?
If the answer is “no”, damage from testing can be accepted and destructive on-site
tests may be conducted to determine the resistance of the fastening solution.
It is important to note that in such a case a simplified or statistical evaluation can be
performed. In that case we may need fewer tests.
If the answer is “yes”, damage from testing cannot be accepted. You need to rely on
non-destructive on-site tests to determine the resistance of the fastening solution. A
higher number of tests is required when only a simplified evaluation is possible.