Construction of a Real-Time Hybrid Simulation Testing Facility and Validation for Offshore Wind Turbine System Behavior under Realistic Wind and Wave Loading Conditions

Wind, wave, 1P, and 3P loading subject the offshore wind turbine (OWT) structure to multidirectional long-term cyclic loads that have varying amplitudes, frequencies, and patterns. Therefore, studying the soil-foundation-structure interaction (SFSI) under realistic loading is required to understand the response of the entire OWT during the service life of the structure. This paper presents the establishment and capabilities of a new large-scale multidirectional offshore wind SFSI testing facility at the Advanced Technology for Large Structural Systems (ATLSS) research center at Lehigh University. The new testing facility has unique multidirectional loading capabilities that allow for simultaneous application of realistic wind, wave, gravity loads, and their induced moments at the top of the OWT foundations (i.e., mudline). The capabilities of the new testing facility also include large-scale real-time hybrid simulation (RTHS) testing. These capabilities provide the ability to evaluate the response of the whole OWT structure under loading. In addition to presenting the design, concepts, and framework of the facility, this paper presents validation results for the RTHS framework of OWTs using small-scale tests. These small-scale RTHS tests are used as a first step to prepare for conducting large-scale RTHS tests.