An Equivalent Wind State Method for Efficient Fatigue Screening Assessments

Abstract A dedicated wind induced fatigue analysis using full scatter diagram is desirable for reducing the design uncertainties in the assessment, even though it is demanding regarding engineering efforts, especially for large structural engineering projects that require the wind buffeting fatigue calculation for many different substructures. To conquer this challenge, the current paper proposes a method by condensing wind scatter diagrams to much fewer wind states for calculating wind induced fatigue damage, which can dramatically reduce the calculation efforts. By adopting a nonlinear time domain dynamic analysis method and applying the proposed method into the fatigue damage calculation of two types of structures, with different dynamic characteristics from each other, the obtained fatigue damage using the proposed method is compared with that using full wind scatter diagram. The comparisons show that the proposed method can reach a satisfied engineering accuracy and efficient for concept and preliminary engineering design. To further reduce the assessment efforts, by adopting the equivalent wind state method, a method to calculate the fatigue damage based on a static analysis is proposed. The method is especially suitable for relevant engineering projects requiring a large amount of screening assessment efforts for wind induced fatigue.