Research On Critical Problems In The Design Of Narrow-base Steel Pipe Tower

Small root span tower is the height to the Tower of the root opening ratio greater than 10, Small root span tower not only save land resources, reduce the width line corridor, saved young athlete compensation, and as with ordinary steel towers, processing, transportation, Assembly, convenient maintenance and so on. Because of the small root the root drive of Small root span tower, characteristic of internal forces, there are many problems in the design, such as wind-induced response and wind-induced vibration coefficient of determination, Eiffel effect of Small root span tower geometrical nonlinear analysis of structure stress effects and so much needed in-depth study.Based on the engineering background of a double-circuit 220kV narrow base transmission tower, a precise finite element model was established and the vibration characteristics of structure have been obtained. The time history of fluctuating wind load was accurately simulated by considering the spatial correlation of Kaimal wind spectrum. Combination of dynamic time-integration method, the wind-induced vibration responses of the tower were obtained in the time domain. The characteristics of Mean displacement,Rms displacement and Rms acceleration at different layer of transmission tower have been analyzed in a detailed. Meanwhile, the wind-induced vibration coefficient at different layer of transmission tower were also studied and compared, respectively. Through research, some characteristics of wind-induced vibration of narrow base transmission tower were revealed and the procedure and the results presented in this paper can be used as reference for the design of narrow base transmission tower.The Eifel effect and nonlinear analysis of narrow base transmission tower have been analyzed at the same time.And Some conclusions differ to linear analysis were also obtained.The results can also be used as reference for the design of narrow base transmission tower.This main conclusions are:1) Loads of wind-induced vibration coefficient of Small root span steel pipe Tower in numerical distribution along the height differential, small at the bottom, the upper and wind vibration coefficient of displacements along the height values on basically the same, if the entire Tower of wind-induced vibration coefficient of wind vibration coefficient of displacements are recommended when the same values as the design reference value is more appropriate.2) for a Small root span tower, without considering the effect of Eiffel effect; to consider, from time-domain method evaluates the statistical analysis we can see, oblique internal force basic material in the appropriate section of main materials within the internal forces of 3%.3) on Small root span tower for nonlinear analysis found, Tower body main material of internal force changes and is unlikely to. stress than growth value are is less than 4%; Tower body oblique material stress than growth range for 5%～15%; cross across material of stress than growth maximum is located in variable slope; beam unit analysis and Rod unit get of rod pieces of rally and pressure basic consistent, beam unit calculation of numerical slightly is less than Rod unit of numerical.