3.2. Wind conditions
The force of the wind causes stress on the structure independently of its direction.
The main factors that have an effect on the strength of the wind acting on the crane/load are:
1. Wind speed
2. Load shape
3. Working height
NOTE
For further information, refer to the tables at the end of the chapter:
• TABLE A shows the Beaufort scale and the permitted wind average speed over
10 minutes at a height of 10 metres.
• TABLE B shows the permitted wind speed for operating heights over 10 metres
related to the wind gust speed in 3 seconds.
3.2.1. Wind speed
The permitted wind conditions depend on the position of the boom system.
Operation with the boom system above 45º (X area):
• The maximum Beaufort grade is 5a.
• The maximum average wind speed (in 10 minutes) is 36 km/h.
• The maximum wind gust speed (in 3 seconds) is 50 km/h.
Operation with the boom system below 45º (Y area):
• The maximum Beaufort grade is 5.
• The maximum average wind speed (in 10 minutes) is 38 km/h.
• The maximum wind gust speed (in 3 seconds) is 53 km/h.
NOTE
Use an anemometer for crane operation over 20 m height.
3.2.2. Load shape
The downwind area of the lifted load can cause an unwanted effect on the behaviour of the crane.
Also, the shape and weight of the lifted load can have a greater effect on the forces involved.
Shape: different shapes have different wind effects. For example, a cylindrical shape load has a
different wind resistance than a rectangular panel shape load.
Weight: a heavy load has a smaller effect by the wind force compared to a lighter load.
The main factors that have an effect on the operating conditions are:
• Cw - Drag factor
This factor is related to the wind effect on the lifted load shape. The factor changes depending on
the real lifted load shape:
Safety precautions and warnings
22 EFFER 265-315-395-525 Progress 2.0 CE
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