Stability Study of Guyed Tower Under Ice Loads

The effect of ice accumulations on the stability of a special type of tall guyed communications tower is examined under conditions of light wind. The 1500-ft high tower is guyed at seven levels. The top-most level, which comprises the primary signal-transmitter, consists of 24 cables, spaced 15° apart. At all other levels, three cables are used, spaced 120° apart. Design provisions for considering ice on towers, and tower failures under icing conditions are briefly examined. The technique used to determine the ice thickness at which collapse is imminent (critical ice thickness) is described. Results of applying the approach are presented, and the effect on critical ice thickness and relative cost of making certain modifications is investigated. The modifications considered include increasing guy initial tensions, stiffening of the web and guy system, and increasing the face width of the tower shaft.