Probabilistic combination of earthquake and operational loads for wind turbines

摘要: This paper provides a probabilistic basis for appropriate resistance and partial load factors to facilitate design and installation of resilient wind turbines in seismically active regions. This study subjects a 5-MW wind turbine model to stochastic wind loads and historical records of earthquake motions, and simulates dynamic structural responses using the National Renewable Energy Laboratory (NREL) FAST code. The simulation takes into account the aeroelastic behaviour of the turbine. The research develops structural demand models and employs probabilistic load modelling and modern reliability-based load combination techniques to assess load combination requirements involving operational and earthquake loads. The study compares different load combination alternatives for meeting different performance objectives. With the target annual reliability index β= 2.5 with a 0.6% failure probability, the investigation observes that partial load factors of 1.1 and 1.4 should be applied to computed mean operational and seismic loads, respectively, when combining these loads for a running wind turbine. Furthermore, the nominal strength of the tower should be reduced by a resistance factor of 0.7. As presented, the load factors are not directly applicable to seismic load effects computed based on design values from current codes of practice. However, the analysis and reliability-based approach offer a rational basis to improve future load combination criteria in provisions for wind turbine design.