For Offshore wind turbines , Grout connections between Monopile (MP) and Transition Piece (TP) have so far been used to ensure power transmission between the steel pipes. Recent developments show that a ring flange connection with high-strength pretensioned bolts can be used instead of a grout connection, whereby the MP must already be manufactured with an RFL.
The ram energy is applied directly via the ring flange. This process requires a high degree of precession so that the flange of the TP can be attached later on without any problems.
The dynamic laoding caused by the pile-driving process causes high stress amplitudes in the ring flange and the weldseam. In this respect,"pile driving fatigue" must be taken into account when accumulating the operating load collectives in order to be able to make statements about the service lifetime . Imperfections of the ring flange can lead to stress increases in individual sections, so that these influencing variables must also be taken into account when fatigue checks is performed. In this respect, knowledge of the pile driving process as an interaction between hammer, pile and soil on the one hand and the quantitative effects of the parameters on local stress conditions on the other hand are important. SKI's engineers are able to dynamically simulate the pile-driving process and check the corresponding dimensions.