Nonlinear Analysis On Static And Dynamic Characteristics Of UHV Guyed Transmission Tower

Guyed tower maintain its banlance by flexibility guy cables which will lead to the nonlinear characteristic of small strain and large displacement in guyed tower, and it is quite different with self-supporting tower’s. Whether the guyed tower can satisfy engineering demand becomes a new subject. So, nonlinear analysis on static and dynamic characteristics of UHV guyed transmission tower is very important for the design and safety of guyed transmission lines.In this paper the guy cable’s static and dynamic characteristics is analyzed, finite element method on guy cable’s static and dynamic characteristics is presented, the static and dynamic characteristics, and the wind-induced response of UHV single-mast guyed tower is obtained. The contents of this paper as follow:(1) The relation equation of guy cable’s elongation and stress is derived, the quantitative description of guy cable’s support stiffness to mast is presented, and the guy cable’s static characteristics are analyzed. The guy cable’s dynamic model is built, the free vibration equation is solved, and the guy cable’s dynamic characteristics are analyzed.(2) In consideration of the characteristics of UHV transmission tower’s guy cable, the guy cable’s accurate finite element model based on bilinear bar elements is analyzed, and a new guy cable’s whole simplified model based on one mutiple linear bar element is presented. Result shows:The whole simplified model based on one multiple linear bar element has high accuracy and efficiency, and it is suitable for guy cable’s analysis on static characteristics.(3) The guy cable is modeled by the whole simplified model based on one mutiple linear bar element, the UHV guyed transmission tower model is built, and the guyed tower’s characteristics under wind forces are analyzed, the definition of guy cable’s critical initial prestress is presented, the influence of guyed tower’s characteristics subject to guy cable’s initial prestress is discussed. Result shows:Under the condition of high wind, the mast’s downwind rigid body rotation around bottom is the major factor caused downwind displacements of the mast’s nodes; the definition of guy cable’s critical initial prestress has contributed to understanding and describing the guyed towers’s characteristics subject to guy cable’s critical initial prestress.(4) The guy cable is simulated by accurate finite element model base on bilinear bar element, the guy cable’s dynamic characteristics are analyzed. The guyed tower’s finite element model for dynamic characteristics is built, the influence of guyed tower’s dynamic characteristics subject to guy cable’s initial prestress is discussed, the mechanism of UHV single-mast guyed tower’s torsional vibration is presented. Result shows:The first mode of the UHV single-mast guyed tower is torsional vibration; the UHV single-mast guyed tower’s torsional model of two degree of freedom has high accuracy.(5) The model of UHV guyed single-mast transmission tower-line system is built by modeling the wires and guy cable in the middle tower with accurate finite element model base on bilinear bar element, and the guy cable in other tower with the whole simplified model based on multiple bilinear bar element. The time history’s charateristics of wind-induced response is analyzed by simulating the wind with linear filtering method, and computing wind-induced response by Newmark method. Result shows:guyed tower produced torsional resonance around the axis of the mast; wind-induced response of displacements of nodes, the max values of leg members and diagonal members are all larger than corresponding values under static equivalent wind loads.