NUMERICAL APPROACH TO THE GALLOP OF ICED CONDUCTOR

A finite element method is presented to analyze the gallop characterized by the high amplitude vibrations of iced transmission line conductors. The iced conductor is modeled by a three-node isoparametric cable element with a parabolic shape function. The insulator strings and remote spans are also modeled as equivalent springs. Besides a steady wind flow, the turbulence is simulated by a harmonic superposition method. A time marching algorithm using Newmark-β method in conjunction with Newton-Raphson iteration is adopted to integrate the dynamic equilibrium equation involving geometric nonlinearities and nonlinear wind loads. The factors influencing the gallop are discussed in detail.