o_19jdnovcg1eh21852116govv1lgra.pdf

case, which is why usually a limiting of
the wind force in operation mode is not
possible.
LED display 5 x 3.0 m erected
Base a = 3.0 m
For wind force > 8
required ballast at A → 960 kg
required ballast at B → no ballast
A further comparison shows the influence
of a reduced base on the ballast:
LED display 5 x 3.0 m erected
Base a = 1.50 m
required ballast at A → 1920 kg
required ballast at B → 820 kg
Indoor riggs
For indoor use horizontal compensation
loads for inclination, stabilization
loads and/or loads for impact of persons
have to be taken into account for
the bracing. (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 systems correspond to the outdoor
riggs.
Furthermore it should be noted that a
frame construction only with ‘sleeveblocks’
is not sufficient indoor, too. The
guiding pulleys usually have so much
clearance that they only have contact
after tilting of the column. Additionally
the stress of transverse bending would
have to be verified, that results from
the contact of the guiding pulleys to
the truss under bending.
For these riggs the minimum horizontal
load for unintentional inclination is:
H = V / 200 and
V / 100 simplified as V / 50
It should be kept in mind that columns
on base plates with small dimensions
stand on their own but get already
instable at a slight addition of horizontal
loads.
Example
Columns: truss w= 35 cm on base
plate 40 x 40 cm:
with h = 3.50 m
average height of the rig
by crowd:
Hs > 0.5 kN at h = 1,0 m
payload and self weight:
V = 2.0 /2 = 1,0 kN per column
with H = 1.0 / 50 = 0.02 kN
A. → Mtilt = 3.5 x 0,02 = 0.07 kNm
by crowd
Hs > 0.5 kN in Höhe h = 1.0 m
B. → Mtilt = 0.5 x 1.0 = 0.50 kNm
the tilting moment has to be smaller
than the stablity moment
with safety of 1.3:
Mtilt x 1.3 < V x 0.18 m
A: 0.07 x 1.3 = 0.091 < 1.0 x 0.18 = 0.18
B. (0.07+0.5) x 1.3 = 0.74 >> 0.18
Four times below the safety!
Conclusion: Columns that are restrained
at the base have to be designed
with sufficiently stable basement with
outriggers or with the possibility of ballasting
or with a plugged and ‘strong’
base plate.
GROUND SUPPORT
Autoren:
Frank Bastians, Stefan Krasenbrink, Jan Keppler, Ralf-Harald vom Felde.
Weitere Informationen gibt es von den Autoren unter:
www.krasenbrink-bastians.de sowie www.vom-felde.de
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