![]() ![]() The largest EAC movement within all models can be measured at the tip of the jacket leg. A sensitivity study is then performed by increasing the contact area. These configurations are designed with respectively two, three and four brackets yielding the same contact area. This is achieved by investigating three phases: 1) simulating a number of load cases on a global jacket model and extracting interface forces near the seabed, 2) using these interface forces to assess the EAC movement on a detailed pile-leg reference model with a full circular stopper 3) analysing this reference stopper by testing three modified configurations. The objective of this research is to gain insight into the modelling approach and the magnitude of EAC movements and investigate how they can most efficiently be minimized. ![]() The strict regulation forces companies to use expensive EAC mitigation concepts of which the real effects are a debated issue. The DNV GL has restricted this relative movement to a conservative 1 mm within the first 24 hours due to a research gap on the subject. This movement, which is called Early Age Cycling (EAC), can cause crack formation in the cured grout therefore decreasing the shear capacity of the connection. As a result, the jacket leg will move relative to the foundation pile. During the curing period of grout, generally taken as 24 hours, environmental loads cause the jacket to oscillate in various directions. In order to rigidly fix the connection, grout is pumped into the annulus between the pile and leg. The jacket is then lowered on top until the legs are resting on the foundation piles through friction-based stopper connections. The most common installation method for a jacket structure nowadays starts by driving the foundation piles in the seabed through a pre-piling template. The yearly installed percentage of offshore wind jacket substructures is rising. Norwegian University of Science and Technology (NTNU) Van der Veen, Maarten (graduation committee) Early age cycling in the grout connection of an offshore wind jacket structureīoogaart, Lukas (TU Delft Mechanical, Maritime and Materials Engineering) ![]()
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