Abstract:
The aim of this research is to study the fatigue performance of the high-mast lighting
towers made up of steel under various thicknesses of the mast-arm wall subjected
to along and vortex shedding wind action. For these kinds of wind sensitive
structures, it is necessary to predict the total damage induced by the wind action. In
order to estimate the vortex shedding induced forces on the high-mast steel arm, the
fundamental basic wind velocity was obtained for zone 3 of wind zonation map of
Sri Lanka. In this study, total damage was estimated, when the wind motions
occur simultaneously in along-wind and vortex shedding wind mode. Fatigue
study was carried out using S-N Curve with consideration of the stress acting at
the base of the mast-arm which was obtained from the simple beam bending
theory. Palmgren-Miner theory of cumulative fatigue damage method was used to
study the cycles to failure for each band in the spectrum and the total damage
due to wind action. It can be concluded that, the thickness of the mast-arm wall
is a key parameter for the fatigue performance of the high-mast lighting towers
and this method allows for the selection of the most cost-effective mast-arm wall
thickness with consideration of fatigue life of the mast-arm system.
