A Two-Stage Optimization Design of Jacket Structures for Offshore Wind Turbines with Integrated Parallel System Verification

This paper presents a novel two-stage optimization framework for offshore wind turbine jacket structures that integrates gradient-based optimization with comprehensive system verification. The methodology addresses the challenge of balancing structural efficiency with reliability through sequential optimization and validation phases. Applied to a 5 MW reference turbine, the framework achieved a 34% reduction in steel mass while maintaining all structural performance requirements. The optimized structure preserves its fundamental natural frequency at 0.294 Hz within the required soft–stiff frequency band, effectively avoiding resonance with rotor excitations. Structural verification demonstrates significant improvements in joint performance, with a 42.35% reduction in the Maximum unity check value of joint shear. Dynamic analysis confirms consistent performance of OWT under the operational cases before and after optimization, with particular sensitivity to structural modifications observed during parked conditions due to absent operational damping.