Offshore wind turbines are subjected to severe loads from wind, waves and saline water.
Source: BAM
The construction of wind turbines is an important part on the way to climate neutrality and decarbonization of the energy sector. Compared to similar wind turbines on land, offshore wind turbines operate more efficiently. However, these offshore facilities are also exposed to harsher environmental conditions such as higher wind pressure, waves, and aggressive salt water. Within the scope of an internally funded research project for Service life extension and service loading fatigue of wind turbines (LeBeWind), BAM investigated potential damage sources and developed technical solutions for repair concepts. Besides rotor blades and components that are susceptible to corrosion, grouted connections were investigated.
Grouted connections are connections between the pile foundation and the upper tower of the wind turbine. These connections are formed by filling the annulus between two members with dissimilar dimensions with a high-strength grout, where the infill acts as a load transfer medium. These grouted connections of offshore wind turbine structures are susceptible to degradation due to repetitive adverse bending moments in conjunction with axial loading. Therefore, cracks can be formed in the grouted connections during system operation. With the scope of the research project LeBeWind, BAM developed a mineral-based repair grout that can be injected in cracks of damaged grouted-connections. Laboratory tests revealed that a repaired grouted connection achieves comparable peak load and load-displacement behaviour than an undamaged connection.
Potential of a Repair System for Grouted Connections in Offshore Structures: Development and Experimental Verification
Götz Hüsken, Md Shamsuddoha, Stephan Pirskawetz, Detlef Hofmann, Matthias Baeßler, Hans-Carsten Kühne
published in Marine Structures, Vol. 77, page 102934 , 2021
BAM Division Buildings and Structures, Division Technology of Construction Materials, Division Fibre Optic Sensors