Berechnung der Rammschädigung an Flanschen von Monopile-Gründungen

Determination of pile-driving fatigue at flanges of monopile foundations.

Cost-efficient design concepts of monopile foundations for offshore wind turbines have recently focused on bolted ring flange connections. The bolted connection between the monopile and transition piece implies that the pile-driving operation by means of a hydraulic hammer is directly performed on the flange. The highly dynamic pile-driving loads may lead to substantial pre-damages at the flange structure and weld. For the determination of pile-driving fatigue, the initial hammer strike as well as an induced oscillation has to be considered. In this paper, the main parameters defining a pile-driving analysis are presented. Basic pile-driving effects are investigated by application of a one-dimensional wave equation analysis. The results are used to validate a detailed finite element (FE) model which simulates the initial hammer strike as well as the dynamic response of the pile-soil interaction. Based on the calculation results, recommendations for design optimizations and evaluation methods of pile-driving fatigue are provided.