RELIABILITY OF MICROWAVE TOWERS AGAINST EXTREME WINDS

The reliability of antenna tower designed for a n-year design wind spe ed is determined by considering the variability of the strength of the component members and of the mean wind speed. For obtaining the n-yea r design wind speed, maximum annual wind speed is assumed to follow Gu mbel Type-1 distribution. Following this distribution of the wind spee d, the mean and standard deviation of stresses in each component membe r are worked out. The variability of the strength of members is define d by means of the nominal strength and a coefficient of variation. The probability of failure of the critical members of tower is determined by the first order second moment method (FOSM) of reliability analysi s. Using the above method, the reliability against allowable stress fa ilure of the critical members as well as the system reliabilities for a 75 m tall antenna tower, designed for n-year design wind speed, are presented.