Long term simulation of wind-induced fatigue loadings

This paper deals with the fatigue analysis of slender structures subjected to the wind action. A 50-year conditioned Monte Carlo simulation of the bending moment at the base of a steel lighting pole is performed. Long-term simulations of the static part of the bending moment, related to the mean wind speed, are combined with short-term fluctuations due to the turbulence. Multiple time series of the stress at the base of the pole, with length ranging between 10 min and 3 days, are generated and processed by means of the Rainflow counting algorithm. The resulting large size data set of the fatigue damage is analyzed in order to clarify some cloudy issues related to the fatigue analysis: the contribution to the damage of the low-frequency, large-amplitude cycles in the stress-time series; the contribution of the transition cycles between consecutive wind states; the length of the stress-time series necessary to get a reliable stress cycle histogram in the framework of the classical state approach; the variability of the damage resulting from a given mean wind speed; the variability of the annual damage.