Closed form solution of the alongwind-induced fatigue damage to structures

Wind-induced fatigue is a crucial topic in the design of several structural types. Despite this, the methods proposed in the literature have been developed mainly for research purposes. As a consequence, reliable engineering and standard methods for wind-induced fatigue analyses are still very limited and mainly addressed to the crosswind-induced fatigue caused by vortex shedding. Based on these considerations, this paper proposes a novel approach to evaluate the alongwind-induced fatigue of slender structures and structural elements. Starting from the procedure recently proposed by the authors, a hierarchy of hypotheses is introduced and critically discussed, which leads to a progressive simplification of the basic formulation. Two levels of formulae are derived, namely a closed form solution and an approximated closed form expression of the wind-induced damage; these represent a solid base from which to derive suitable methods for engineering calculations and standards. Application of the proposed solutions shows good agreement with numerical results.