Steel tower structures fatigue analysis taking into account the influence of wind vortex shedding

In this work, the aspects of solid cross-section steel tower structures fatigue analysis, taking into account vortex shedding, are considered. In scientific and regulatory literature on the design of building structures, as well as in design practice, it is customary to take into account the influence of frontal wind on buildings and structures as a whole, as well as their structural elements. At the same time, tower structures are characterized by a special phenomenon - vortex shedding, when under the action of a frontal wind due to the successive breakdown of vortices, the structure oscillates in a plane perpendicular to the wind. Oscillations from vortex shedding occur according to their own oscillation frequencies at wind speeds higher than critical values, which, as will be shown, can be in the range of already moderate winds and higher. There is a question of assessing the number of oscillation cycles and the stress-deformation state of construction structures and their details for the entire period of operation in order to determine their durability. Analytical studies of the effect of vortex wind shedding were conducted in four tower structures with a continuous cross-section from 12 m to 48 m in height, which showed that most often in structures with vortex excitation, oscillations at the first natural frequency of oscillations are manifested, and the effect of vortex shedding increases significantly with an increase in the height of the structure. The time of winds with a speed higher than the critical speed was determined in one randomly selected year for the city of Kyiv from the weather archive published on the Internet resource, which showed that the number of oscillating cycles per year for the structures under study exceeds 1 million. This indicates the need to limit stresses in systems to the limit of endurance. Also considered is the aspect of the influence of the shape of the cross-section of structures on the stress-strain state, taking into account vortex shedding.