Research On Wind Load And Wind-induced Responses On Long Span Steel Tubular Tower

The current development trend of transmission towers is higher altitude and longer span,which make the long span transmission tower and tower line system more sensitive to wind loads.Therefore,accurately obtaining the aerodynamic and wind load parameters of the transmission tower and tower line system is an important guarantee for the transmission tower design.The long span steel tubular tower is higher in height and longer in span than the conventional tower,and the wind load of the steel tubular tower is affected by many factors and is difficult to calculate.It is of great engineering significance and economic value to carry out comprehensive wind load research on transmission tower and tower line system.This paper took the Zhoushan large-span transmission tower and tower line system as the research object,combining wind tunnel test,numerical simulation and theoretical analysis,the following studies were carried out:1.Aerodynamic coefficient and Reynolds number effect of circular section members:Mainly for the smooth cylinder of 0.3m diameter,pressure-measuring wind tunnel test were carried out under different wind speeds in uniform flow and three turbulent flows respectively.The average wind pressure and pulsating wind pressure on the cylindrical surface under different Reynolds number and flow turbulence were obtained in the tests.The wind pressure symmetry of the cylindrical surface was analyzed,and the characteristic parameters of the wind pressure distribution curve under different turbulences were compared with the various Reynolds number.The correlation between the wind pressure coefficients of the cylindrical surface under different turbulences was studied,and the average and pulsation values of the drag coefficient and lift coefficient under different Reynolds number and turbulence were calculated.The lift coefficient spectrum,the drag coefficient spectrum and the change of Storoha number under different Reynolds number and turbulence were analyzed.Meanwhile,the pressure test and force test were carried out on various cylinders to study the effect of surface roughness on the Reynolds number effect.Finally,the experimental results of the Reynolds number effect were compared with the national norms,and the reasonable Reynolds number effect conversion coefficient of the circular section member was given.2.Aerodynamic coefficient of cross-arm and tower body of long span transmission tower:High-frequency balance force test for three types of cross-arms,tower body and the whole long span tower of 380 m height were carried out and the drag coefficients was calculated which was compared with the norms.A verification method for wind tunnel test results by comparing the load calculated by the drag coefficient of cross-arms and tower body and the force measurement of the whole tower is proposed.3.Systematic analysis of aerodynamic coefficient of conventional steel oole cross-arm:The effect of solidity ratio and aspect ratio on the two types of cross-arm was studied by using integrated cross-arms.The change rules of drag coefficient with the various solidity ratio and aspect ratio at vrious wind angle were studied and the results were compared with the norms.Finally,according to the results of the wind tunnel test,the recommended calculation formulas for the angular distribution coefficients of the two types of cross-arms were given which were compared with the norms as well4.Wind-induced response and equivalent wind load of transmission tower based on HFFB test:For the high-frequency balance test of the long span tower,the three-dimensional design wind load of the long span tower was obtained according to the assumption of the linear mode,and the wind load accumulating value based on the base shear force and the base bending moment of the long span tower and the wind vibration coefficient of the whole tower were given5.Wind vibration characteristics and wind vibration coefficient of the long span tower:A finite element modeling of long span transmission tower was built by using ANSYS,and then time domain calculation of wind-induced response was performed.The frequency domain calculation of the long span tower was performed througth a modal decomposition method including CQC method and SRSS method,and a background-resonance calculation method.An aeroelastic model of a long span tower with a geometric scale ratio of 1:200 was designed and a wind tunnel test was conducted.The wind-induced response results obtained by various methods were discussed and the calculated wind vibration coefficients were compared with the norms.6.Wind-induced response characteristics and coupling of tower-line systems:The aeroelastic model wind tunnel test and finite element calculation of tower-line svstem were used to study the natural vibration characteristics,wind-induced response,wind vibration coefficient and tower-line coupling effect of the long span tower-line system.The wind-induced response of the tower-line system in finite element simulation and wind tunnel test was compared,and the wind-induced response of the single tower and tower-line systems was compared as well.Finally,the tower-line coupling system and the non-coupling system are designed by ANSYS.The similarities and differences of wind-induced responses of the two systems are analyzed by finite element calculation.7.Characteristics of wind field on a ideal hill and its effect on the wind-induced response of the transmission line:A wind tunnel test of a hill with cosine-type shape was conducted,and the mean and pulsation values of downwind and vertical wind speed were analyzed.The speed-up ratios in the down wind direction were compared with the vaious norms.Finally,the wind load of the long span tower and the wind deviation of jumper cable were calculated under the condition of hilly wind field,and compared the results with these in the flat wind field.At the same time,in addition to considering the downwind wind speed,the wind deviation of the jumper cable was calculated considering the vertical wind speed.