Zum Tragfähigkeitsnachweis für horizontal belastete Pfähle für die Grenzzustände GEO-2 und GEO-3

On the capacity proof for horizontally loaded piles for GEO-2 and GEO-3 limit states.

Horizontally loaded piles are often used in offshore applications, recently in particular as foundation elements for offshore wind energy converters. Here open-ended steel pipe piles are used, which have diameters between around 2 m and more than 5 m. The bearing behaviour of such piles is calculated with subgrade reaction methods, and these methods are also used in the ULS check regarding pile capacity. Internationally, the design is usually done for the GEO-3 limit state, whereas in Germany a design proof for the GEO-2 limit state is compulsory according to DIN 1054. In the paper, parametric studies on that matter are carried out for flexible and stiff or almost rigid piles. It is shown that both methods lead to totally different results for flexible piles. However, this is not relevant since for such piles the limitation of bending stresses in the pile is design-driving. For very stiff piles, both methods give similar results when the usual partial safety factors for offshore structures are applied. For monopiles it is shown that, using the usual safety factors and in particular the same load factor as for GEO-2, the GEO-3 proof usually gives conservative results.