Abstract
The stress distributions of the member, the deflections of typical points of the full sized model of a transmission tower which was damaged and overturned by the typhoon-ISEWAN on 26 Sept. 159 were measured by loading test. The applied loads were equal to the actual dead load by angle effect of line tensions, the dead weight of tower. and the wind pressure on the wires and the tower. The tests were made by two cases (a) and (b). In the test (a), the wind direction was assumed to be normal to the transmission line, and the loading was limited in elastic range alone, and in the test (b), the wind direction was assumed to be inclined as 45° to the line, and the loading was applied up to the failure. The ultimate load reached up to 2.2 times of the desingn load, and this load was equivalent to the wind pressure due to its velocity 70m/sec when the reduction factor of the velocity pressure on wires was assumed as 0.6 to that on the tower itself. The actual wind velocity at the site to the destroyed tower was supposed to be about 65m/sec from some investigations. The collapse is considered to be caused by the dynamic effect of the wind together with the static wind pressure.
