o_19jdnovcg1eh21852116govv1lgra.pdf

EVENT TECHNOLOGY I
Trusses in event technology according to Eurocode
... to continue
framework. This is why the interaction of axial force and
bending moment is eventually decisive for the main chord.
Based on these values load charts can be compiled. As
described above attention should be paid to the included
safeties on the loading side.
Application of load charts
Almost every truss manufacturer provides load charts of his
trusses for the user. In these charts permissible loads are
given in the form of uniformly distributed loads (UDL) or
single point loads.
But how can these charts be evaluated, how can I use them
and are the given values binding? The user faces a lot of
questions. With this article we would like to try to facilitate
the application of the load charts, resp. explain some basics.
The load charts are supposed to make the bearing capacities
of the trusses clear to the user. For this purpose usually the
system of a single span beam is chosen since it is the simplest
system.
Furthermore the following fundamental basic conditions apply:
• truss is only vertically loaded
• load introduction at the nodes of the bracings and the
main chords
• support at the nodes
• uniform distribution of the loads on two chords
Since these requirements are almost never completely
fulfilled (especially the load introduction at the nodes and the
uniform distribution of the loads) BGI-310-3 recommends to
reduce the given bearing capacity by 20 %. Of course it is
generally possible to utilize the given values completely if all
requirements are fulfilled. If a system is utilized that heavily a
structural analyst should always be consulted.
In which cases can I use the load charts?
Since the load charts are usually calculated for a single span
beam they can only be used for such a system. For all other
systems the charts are actually invalid.
In practice often other conditions are found. In the following
requirements for an approximate pre-dimensioning of often
used systems are given. The major problem of the transfer of
the given loadings of a single span beam to other systems is
the interaction of axial force and bending moment at the
coupler, since the combinations of shear force and bending
moment differ from system to system. Because of that it is
demanded to arrange no couplers in critical zones or to
reduce the permissible loads additionally by 25 %.
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