Simplified Fatigue Assessment for Slender Structures using adjusted Damage Equivalence Factors

摘要

Wind excited stress range spectra may lead to structural failures caused by fatigue. Therefore, a proper determination of the expected gust induced vibrations and a subsequent stress analysis including a Rainflow cycle counting is needed. Whereat for the former spectral methods are well established, for the latter various simplifying suggestions have been made in recent years. In the present paper, the Dirlik Equation is used for the counting of short termed structural responses. Convolving with site related wind statistics, realistic predictions of the lifetime related distribution of stress cycles are enabled. Based on the presented methodology, an extensive parameter study has been perfomed in order to discover the dependencies between structural and aerodynamic properties on the resulting stress range distributions. Finally, a simplified approach is presented, which suggests damage equivalence factors, taking into account an individual and realistic shape of the cycle count distribution.