Monitoring based condition assessment of offshore wind turbine support structures

....................................................................................................................... 3 ZUSAMMENFASSUNG ........................................................................................................ 5 1 INTRODUCTION ........................................................................................................... 11 1.1 AIM OF THE THESIS ................................................................................................. 11 1.2 SCOPE .................................................................................................................... 12 1.3 RELEVANCE ........................................................................................................... 13 1.4 STATE OF THE SCIENTIFIC AND TECHNOLOGICAL KNOWLEDGE ............................... 14 1.4.1 Reliability analysis ........................................................................................ 14 1.4.2 Assessment of existing structures .................................................................. 16 1.5 OUTLINE ................................................................................................................ 20 2 ASSESSMENT AND MONITORING OF RELIABILITY AND ROBUSTNESS OF OFFSHORE WIND ENERGY CONVERTERS (PAPER I) ......................................................................... 23 ABSTRACT ..................................................................................................................... 24.................................................................................................................... 24 2.1 INTRODUCTION ...................................................................................................... 24 2.2 DESIGN OF OFFSHORE WIND ENERGY CONVERTERS ................................................ 25 2.3 ASSESSMENT OF OFFSHORE STRUCTURES ............................................................... 26 2.4 MONITORING AND ASSESSMENT OF WIND ENERGY CONVERTERS ........................... 27 2.5 ASSESSMENT AND MONITORING FRAMEWORK ........................................................ 27 2.5.1 Monitoring ..................................................................................................... 30 2.6 APPLICATION OF THE FRAMEWORK ........................................................................ 30 2.6.1 Structural model and loading ......................................................................... 30 2.6.2 Limit state functions ...................................................................................... 31 2.6.3 Uncertainties .................................................................................................. 32 2.6.4 Analysis of structural reliability .................................................................... 33 2.6.5 Monitoring data ............................................................................................. 35 2.6.6 Robustness index for ultimate limit state ...................................................... 35 2.7 CONCLUSION AND OUTLOOK ................................................................................. 36

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