Study On Wind Load Spectrum Research Of UHV Transmission Tower Based On High Frequency Dynamic Balance Test

As a kind of high flexible and highly sensitive structure,the wind effect of UHV transmission tower is the main factor to control the safety of the structure,and the wind load spectrum is the precondition in the wind effect,and there is still a great uncertainty in the existing research.When the first order mode of vibration is considered and the first order mode of vibration is assumed to be linear,the rigid model base bending moment obtained by the high frequency force balance test is the first order generalized load in this direction.The wind vibration response of the towering flexible structure of the transmission tower is generally only considered by the first order mode,and it can basically satisfy the assumption of the first order linear mode when the stiffness of the model is large,so the wind load spectrum of the transmission tower can be obtained by the high frequency dynamic balance wind tunnel test.In this paper,a high-precision transmission tower model is designed based on a certain 800 thousand volt high voltage transmission tower,combined with 3D printing technology.In the B geomorphic turbulent wind field,the dynamic balance test of the high frequency dynamic balance of the whole tower and the tower section is completed in a segment by section,and the typical tower section three force coefficient and wind load spectrum in the turbulent flow field are studied.The work and conclusions are as follows:(1)Design and fabrication of fine wind tunnel test model for transmission tower.Based on the 3D printing technology and the line cutting technology,the nodes and components of the wind tunnel test model of the transmission tower are refined,and the wind tunnel test model of the transmission tower with strict geometric similarity is made.The measured results of the model show that the stiffness of the model is large enough to meet the requirements of the high frequency dynamic balance test.(2)In order to consider the influence of the upper and lower adjacent towers of the transmission tower section,the balance test of the tower section at different heights is gradually completed from top to bottom by the way of truncation by section by section,and the three component coefficient of the different sections of the turbulent flow field in different conditions is calculated on the basis of the three force coefficient formula.The results show that the tower head,the tower foot and the adjacent lattice have a higher figure coefficient,and the lift coefficient increases gradually with the increase of the wind angle;the drag coefficient presents a parabolic trend and the maximum at 15 degrees;the square root coefficient of the lift is monotonically increasing with the increase of the angle,and the square root coefficient of resistance is present.There is a small degree of first increase and later decreasing trend,the maximum of the existence coefficient at 15 and 30 degrees,and the larger torsion of the connection between the tower head and the tower body and the connection between the tower foot and the tower body.(3)For the system composed of the model and the balance is not completely rigid,the bending moment spectrum measured by the balance has a more obvious resonance effect,and the filter formula is filtered through the derivation of the filter formula.According to the unified formula of Davenport pulsating wind power spectrum,the wind velocity spectrum of wind tunnel is obtained by fitting corresponding parameters.Then,the formula of generalized load spectrum is fitted by the relationship of load spectrum and load spectrum based on the quasi constant assumed wind spectrum and load spectrum obtained from the balance test,and the fitting formula of the conversion function is obtained.