Fig. 3 Calculated tower deflection and stress distribution inthe tower in the case of characteristic wind load (a) thedeflection of tower vs. the height of the tower (b) thecomparison of the axial stress distribution in the shell wall.Stress associated with the buckling is the axialcompressive stress in shell. Axial stress distribution at acritical position, e.g. in the lower portion near the base of thetower, and at the middle portion of the tower height isillustrated in Fig. 3b. Little difference in stress amplitude canbe observed on the graph for both positions. Similar stresscharacteristic is that the positive axial stress can be found inthe tower wall which is against the wind. On the oppositesurface, shell wall is subjected to the compression asindicated as the negative stress values on the graph. Adiscontinuous stress distribution in the lower portion from135 to 225 degree is occurred since this portion locates nearthe opening door.Impulsive wind force due to the extreme gust is aninstantaneous situation that can take place during theoperation of a wind turbine power plant and it is vital toverify its effect on the structural damage.
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