Experimental investigation of offshore crane load during installation of a wind turbine jacket substructure in regular waves. (1st December 2021)

• Record Type: Journal Article
• Authors: Aliyar, Sithik; Meyer, Jannik; Sriram, V.; Hildebrandt, Arndt
• Is Part Of: Ocean engineering. Volume 241(2021)
• Publication Date: 2021-12-01
• Subjects: Jacket structure -- RAO -- Upending -- Motion response -- Offshore crane operation -- Experiments -- Buoyancy tank; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2021.109979
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Installation of offshore structures for harvesting energy or oil and gas industries is still burdensome because of the rough sea state. Unless a calm water condition prevailing, installing any substructure or floating structure at offshore sites is very difficult. Hence, there has been great potential for research to investigate offshore structures' installation for normal and more energetic wave conditions. To understand and develop the methodology for the installation, the hydrodynamic response of the structure and impact received by the offshore crane is vital. In this context, the present study focuses on installing a heavy concrete jacket foundation sub-structure (Equivalent steel jacket) of an offshore wind energy structure. Due to the heavyweight and the temporary buoyancy tanks, the structure's response during installation is different from the tubular steel structures predominantly used for jacket structures. In this work, the structure's response in regular waves at different positions of upending is analysed. Also, the peak force received by the crane at different sea states is measured for different positions of upending. Finally, the forces to be expected while upending the jacket in waves is quantified, and a suitable weather window is suggested. Furthermore, the critical positions in upending are established. Highlights: The upending of the heavy concrete jacket structure in regular waves is reported. The responses for three upending positions 16, 45 and 90 deg are investigated. The peak force experienced by crane at 16 deg is 1.5 to 2 times higher than the rest. Max. peak force was found to be 3 times the weight of the jacket in initial position. RAOs of all motions decreases by 2 to 2.5 times, when jacket is connected to crane. Differences in free-floating and crane rope connected conditions are reported.