Experimental Study On Tower-Lines System Of Ultra-High Voltage Glass-Shaped Transmission Under Multiple Array Shaking Tables

Ultra-High Voltage transmission(UHVT)tower-line system is one of the most important infrastructures in our society.It has a great practical significance of UHVT tower-wire system both on safety and effective operation.However,it is found that the damage of the UHVT tower-lines system is serious during earthquake according to the investigation on several large earthquakes around the world in recent years.Therefore,it is necessary and meaningful to conduct the seismic research on UHVT tower-line system.This report was based on the background of one million Volt AC UHVT engineering suspension tower of Ximeng-Shandong Project.Shaking table tests of UHVT tower-line system with the geometric similarity ratio of 1:15 scale were carried out analyzing the seismic response of model under seven and eight degrees with basic intensity,frequent intensity as well as rare intensity.The influences of bidirectional excitation’s effect and traveling wave effect on the dynamic response of model at 0.21g were analyzed and compared.The main conclusions are as follows:1.The UHVT tower-line models were designed and manufactured,and the shaking table test method for UHVT tower-line system was improved.The frequency similarity ratio between model and prototype was analyzed and the rationality of the design model was verified through the test.The 1 st and 2nd nature frequencies of the single tower without added mass are 16.388Hz and 17.412Hz separately,which agree with the similarity design.The 1st and 2nd nature frequencies of the single tower with added mass are 7.202Hz and 7.568Hz separately compliant with mass similarity design.However,damping is obvious different that lines can significant increase the system’s damping.2.The results of one-tower and two-line model show that its 1st and 2nd frequencies are 0.82%decrease and 4.23%decrease than that of one-tower.It can be known that the nonlinear vibration of line can reduce the tower’s frequency,which is benefit to the seismic performance of model tower.Moreover,the influence of the line to model tower in vertical direction(Direction Y)is greater than that in the longitudinal direction(Direction X).By analyzed the amplification factor of structure,the coupling effect between line and tower and nonlinear shake have great effect on response of Direction Y.though the amplification factor of cross arm can be reduced and the seismic response is decreased in bidirectional excitation,the seismic response of low part of the tower is increased.3.The model of there-towers and four-lines testing results show that the models are still under the elastic stage during the whole process of the test,and nonlinear response characteristics for towers are not obviously observed.The model(there-towers and four-lines)is basically in the elastic stage under the effect of 8-degree of rare intensity and no damage or crack was occurred,which show a good anti-seismic property.However,strain response and amplification factor of the model indicates that the bidirectional excitation can be more adverse to the seismic response of tower body.The seismic response of the structure is affected by the type of input wave under traveling wave effect,which may increase or decrease the seismic response of structure.