STUDY ON COLLAPSE STATES OF TRANSMISSION TOWERS BY WIND-TUNNEL TESTS OF TOWER-LINE SYSTEMS

In order to study the coupling mechanism of transmission tower-line systems and explore failure modes and mechanisms of ultimate states, an aeroelastic model of transmission tower-line systems considering ultimate states was designed based on a 220 kV transmission tower-line system in Guangdong province. The wind tunnel tests of a single tower and a tow-line system in the turbulent wind field were carried out, and the phenomenon of tower collapese under the ultimate wind load of transmission tower-line systems was reappeared. The comparisons of the results between the finite element analysis and the tests showd that:1) Based on the equivalent design of stable stress, the model of the transmission tower under ultimate states could be simulated the structive failure well in the wind tunnel test. 2)In the case of strong wind, the coupling vibration caused by the tower line system made vibration caused by the tower-line system made vibration of the tower-line system more complicated than that of a single tower in the same environment. The failure might be related to the occurrence of nonlinear internal resonances and local responses to be amplified, and the elastic-plastic instability failure would occured. 3) designing of transmission tower structure, the stable bearing capacity of the middle of the tower along the direction perpendicular to the conductor direction should be strengthened, and the contribution of the across-wind vibration response should not be ignored.