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wind zone 1
Kiel Rostock
wind zone 2
wind zone 3 Hamburg Schwerin
wind zone 4
air-termination Bremen
rod with air-
termination tip Berlin
Hannover
Potsdam
Magdeburg
Essen Halle
Dortmund
Leipzig
Düsseldorf Dresden
Erfurt
Köln Chemnitz
brace
Bonn
Frankfurt
Wiesbaden
Würzburg
Nürnberg
Saarbrücken Mannheim
Stuttgart Regensburg
Augsburg
Freiburg
hinged München
tripod

Figure 5.1.11.3 Self-supporting air-termina- Figure 5.1.11.4 Division of Germany into wind zones; source: DIN EN 1991-1-4/NA:
tion rod with hinged tripod Actions on structures – Part 1-4: General actions – Wind actions

This method creates a protected volume where direct lightning therefore basically meet the same requirements concerning
strikes cannot occur. their mechanical stability as set out in EN 1993-3-1, Eurocode 3:
To achieve the largest possible protected volume or to protect Design of steel structures – Part 3-1: Towers, masts and chim-
large roof-mounted structures against direct lightning strikes, neys – Towers and masts.
individual air-termination rods of sufficient height should be Germany is divided into four wind zones (Figure 5.1.11.4).
installed. To prevent self-supporting air-termination rods from When calculating the actual wind load stress to be expected,
tilting and breaking, a suitable base and additional braces are apart from the zone-dependent wind load, the height of the
required (Figure 5.1.11.3). building and the local conditions (detached building in open
However, the requirement that the self-supporting air-termina- terrain or embedded in other buildings) must also be observed.
tion rods should be as high as possible leads to a higher stress Figure 5.1.11.4 shows that about 95 % of Germany´s surface
resulting from the wind loads. At the same time, a lightweight area is situated in wind zones 1 and 2. Therefore, air-termi-
“self-supporting air-termination rod” is required to facilitate nation rods are generally designed for wind zone 2. The use
transport and installation. The stability of air-termination rods of self-supporting air-termination rods in wind zones 3 and 4
must be verified to ensure safe use on roofs. must be examined for each individual case to take into account
the stresses which arise.
Stress caused by wind loads
Since self-supporting air-termination rods are installed at ex- When designing self-supporting air-termination rods, the follow-
posed locations (e.g. on roofs), mechanical stress occurs similar ing requirements must be met with regard to the wind load stress:
to the stress on radio towers due to the comparable place of in- ¨ Tilt resistance of the air-termination rods
stallation and wind speeds. Isolated air-termination rods must ¨ Bending resistance of the rods

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