o_19jdnovcg1eh21852116govv1lgra.pdf

That shows that besides the horizontal force there is also a
vertical force component. The more the plane is stretched respectively
the less it is expanding under load the higher is the
membrane force. Hence the windforce results in a vertical
load that is higher than the horizontal load.
Operating conditions
Stage roofs in the entertainment industry are usually temporary
structures whose construction takes place at different
places i.e. the DIN EN 13814 (standard for temporary structures)
can be applied. For the “Operating state” the wind
loads may be reduced if it is ensured that the canvas is unrigged
from wind force 8. “Out of operation” the remaining
part, i.e. everything that cannot be unrigged or removed,
has to be dimensioned for full wind loads.
The requirements for dismantling for the state “out of operation”
have to be determined with care. For example a requirement
as “from wind force 8 stop operation and let
down the roof” is exactly what you should not do because
a stage roof is usually braced with crossed ropes. If the roof
is let down the ropes lose their tension and the complete
construction becomes unstable.
Another example is the removal of the wall canvas. This can
be quite a problem if the height of the stage is 10 m or
more. The climbing the roof and cutting of the fixations is
life threatening.
Unrigging possibilities
It has to be possible to remove the target areas for wind loads
(usually the wall canvas) which are only taken into account
up to wind force 8 in a short period of time. 10 – 15 minutes
seems to be an appropriate period to us. The unrigging of the
canvas has to be possible from the ground.
Examples for that are:
• Wall canvas in piping profiles
• Detachable connections such as Velcro fastener
• Knotting techniques with untying mechanisms
Day- and night stand-by duty with contact to
a meteorological office
It has to be ensured that at all times staff is on site to take
measures. The current forecasts and storm warnings can be
requested for example of the Deutscher Wetterdienst
(www.dwd.de).
1. Bending resistant corners
Each corner has to be verified.
The bending load bearing
capacity of the corners
is usually smaller than the
load bearing capacity of the
truss. This bracing is normally
only used for indoor constructions.
2. Diagonal bracing
3. Cross bracing
Cross bracings are always necessary for stage constructions
with sleeveblocks, because the bending resistance of the sleeveblock
is very low. To brace a building four bracing planes
are required.
For example stage constructions: cross bracings are placed
in the roof, the back and the side walls.
Hoisting and securing of the roof
This bracing is used for indoor
constructions or outdoor
constructions with small loads
This bracing can be used for
all constructions and is by far
the best alternative.
Common roof systems are assembled at the ground and hoisted
with sleeveblocks. After reaching the end position the
roof has to be secured. For the securing there are different
systems available, for example interlocking systems or the so
STAGEROOFS
Wind speed measurement
The wind speed has to be monitored for every construction
with wind speed limit. For that purpose a wind velocity indicator
should be attached at the highest point of the construction
respectively for constructions with overall height lower
than 8 m the place and the wind speed to be measured
should be agreed with the stress analyst of the construction.
Of course the measures for example for stages whose side
canvas has to be removed at wind force 8, should be taken
precautionary at an early state (before/at reaching measured
wind force 7), particularly in regard to the unrigging time.
Bracing
Every building has to be braced to achieve a sufficient stability
of the construction. This can be achieved in different ways:
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