o_19jdnovcg1eh21852116govv1lgra.pdf

PA-TOWER
PA-Tower
PA-Towers are used indoor and outdoor; normally the decisive factor for the dimensioning
in both cases is not the size of the vertical pay load but of the horizontal loading.
The horizontal loads are substantially wind loads for outdoor
constructions and compensation loads for inclination,
stabilization loads and/or loads for impact of persons for
indoor use. (In the meantime for some exhibition halls a
proof of stability for limited hall wind loads is required.
These loads have to be understood as horizontal compensation
loads.)
The horizontal loads generate tilting moments. Depending
on the position of the pay load to the basement this tilting
moment is enlarged additionally by the pay load.
Decisive for the stability of a PA tower therefore are usually
the dimensions of the basement and the self weight of the
complete construction.
Only for very solid basements the weak point is the tower
itself. In this case the failure of the system results from buckling
combined with bending due to the horizontal loads. For
the corresponding calculations the deformation of the
system has to be taken into account (equilibrium at the
deformed system). These calculations should only be performed
by a structural engineer.
Especially for highly utilized systems caution is required because
an exceeding of the permissible loads can lead to
sudden failure of the system (without advance notice).
Further down it will be explained how the load limit of a
tower can be estimated.
In this article simple dependences between tower height,
pay load, surface area exposed to the wind, necessary
dimensions of the basement and ballast will be explained.
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Please note:
the calculations and examples shown in this article are intended
for estimation. For more precise structural verifications
further points are of importance, respectively more
precise calculations are necessary. But normally the results
of this calculations are similar to the estimation.