Computational analysis of aeolian conductor vibration with a Stockbridge-type damper

An iterative finite-difference scheme is derived to predict the vertical, s teady-state, monofrequent, aeolian vibration of a single conductor span wit h a Stockbridge-type damper attached. This numerical scheme is based on emp irical models developed to represent the vortex-induced lift force from the wind as well as the forces of dissipation associated with the conductor se lf-damping and the damper. The scheme has the capability to account for mor e than one spatial mode of conductor vibration, travelling-wave effects, co nductor flexural rigidity, and damper mass. A two-part numerical analysis i s performed in which the finite-difference scheme is applied to simulate ae olian vibrations of a typical conductor with and without a Stockbridge-type damper. The computed results are employed to investigate (a) the steady-st ate form of conductor vibration, (b) the conductor bending amplitudes near each span end as a function of the vibration frequency and damper location, and (c) the influence of conductor flexural rigidity and damper mass. In a ddition, results from the finite-difference scheme are compared with soluti ons from the widely used energy balance method as well as field data on aeo lian conductor vibrations. The numerical scheme predicts that, with a Stock bridge-type damper attached near a conductor span end, a travelling wave co ntinually propagates towards that span end during steady-state aeolian cond uctor vibration. It also predicts that, with no dampers attached to a condu ctor, steady-state aeolian conductor vibration is essentially in the form o f a standing wave. (C) 2000 Academic Press.