JaBaCo optimises modular jacket design

Aim of JABACO is to develop a Modular Jacket concept composed by components of pre-qualified quality, for cost reduction of offshore wind farms. The concept is based on an integrated design considering water depths 30-80 m, turbine sizes 5-10 MW, in the North Sea and the Mediterranean.

The EU funded project JABACO aims to develop a Modular Jacket concept composed by components of pre-qualified quality. The aim of this project is to reduce offshore wind costs by inplementing prefabrication of substructures, via the development of prefabricated standard components, scalable in a significant range of environmental conditions.

The concept is based on an integrated design considering water depths 30-80 m, turbine sizes 5-10 MW, in the North Sea and the Mediterranean.

The project includes the design of six cases, tests and numerical simulations of structural components conducted together with a sensitivity analysis.

Partners in the project are CSM, Ramboll, National Technical University of Athens (NTUA), IDESA, University of Thessaly (UTH) and OCAS. In this project, OCAS is responsible for fatigue testing on large-scale components performed at high frequency. This includes detection of crack initiation, non-destructive testing to monitor crack growth and post-mortem analysis of the fracture surfaces.

Results

Four X-joints with brace diameter of 711 mm were tested until failure. The failure location differs between specimens, indicating that the manufacturing has an influence on the construction’s weak points.  The fatigue resistance of these tubular joints was compared to the fatigue design curve. The experiments have also proven that the component had a significant part of its fatigue life after crack detection.

“JaBaCo is an important step at optimising jacket foundations and validating their design by unique and accelerated fatigue testing of critical full size jacket joints.”

Philippe Thibaux, Senior Structural Integrity Specialist, Applications and Solutions department, OCAS