o_19jdnovcg1eh21852116govv1lgra.pdf

afterwards "hung dead". This "dead-hanging" should also only
be carried out vertical.
Sometimes it is necessary to suspend inclined (bridle). At an
inclined suspension not only vertical but also horizontal forces
are generated at the attachment points. Depending on the
angle these horizontal forces are equal to or even higher than
the vertical component. They have to be examined
seperately. Often these forces can not be absorbed by the
construction of the hall.
Depending on the angle the forces in the ropes of the bridle
can be a multiple of the suspended load.
Suspended load: 1.0 kN (100 kg) see table
Suspending a rigg partially from the ceiling and
supporting it with pillars
Suspending and in the same time supporting a system is only
possible under certain conditions. It has to be ensured that
the deformation of the roof and the ceiling is very small or
due to the system without influence.
Otherwise the deformation leads to unintentional redistribution
of the loads as described above for uneven hoisting motors.
In the following another example for further explanation:
For the construction shown above it has to be ensured that a
deformation of the roof has no negative influence on the system.
There are roofs and ceilings of halls that are lifted and
lowered several centimetres. For roofs reasons for that can be
a change of temperature (day and night) or loading from
snow and wind, at ceilings live loads can occur which were
not applied when the truss construction was installed.
Securing persons at a truss rigg
Securing persons at a truss rigg with PPE has to be proofed
seperately. If a fall impact absorber is used a fall load of 6.0
kN has to be absorbed. Without fall impact absorber (with
much higher resulting loads) it is unlikely that there are systems
that do not fail at those loads. Many systems can not
even absorb the 6.0 kN! Especially riggs of so called 'decoration
trusses' should be carefully checked and verified that the
attachment of PPE is admissible.
Now we are back at the beginning of our article. Truss riggs are
complex constructions that can be installed only with proper
knowledge. Sufficient structural knowledge is absolutely necessary
for long term damage- and accident-free constructing.
SUSPENDED TRUSS
Autors:
Frank Bastians, Stefan Krasenbrink, Jan Keppler, Ralf-Harald vom Felde.
Further informationen of the autors:
www.krasenbrink-bastians.de sowie www.vom-felde.de
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