Abstract
The models have been derived for the computation of the dynamic
stiffness of guy cables.Both the complete mathematical model and the
simplified spring-mass model can be used in a linear three-dimensional dynamic
analysis of guyed masts in connection with the frequency response method and
a substructure technique where frequency dependent springs and dashpots are
substituted for the guys.The mathematical model can also be used in the design
of linear guy dampers which are included in the model.The analytical formulas
for the static configuration of the guy evolve in both models from the
assumption of uniformity of the guy.The three-dimensional motion of the guy
attachment point to the mast and the two-dimensional sectional guy motions
under the influence of mechanical and aerodynamic damping are considered.The
computational procedure incorporates a variety of mechanisms of aerodynamic
instability, which may result in galloping oscillations.These mechanisms
include the lift and drag instabilities as well as the wake galloping
phenomenon.Examples of the dynamic and aeroelastic behaviour of guys are
computed in terms of the complex dynamic stiffness.The cross-over behaviour of
the natural frequencies is shown to exert significant effects on the guy
action.The dynamic sensitivity of a guy can be assessed using a single
stiffness parameter which depends both on gravity and wind load.The results
disclose that the direction and intensity of the mean wind force have a marked
influence on the dynamoc behaviour of Light guys.Further examples show
various effects of the aerodynamic instabilities on iced and non-iced guy
cables.The mechanism of a galloping phenomenon of guys, which carry an ice
banner below the cable, is explained referring to reported wind tunnel
results.It is shown that mitigation of the galloping problem entails
additional damping in a broad frequency range.The result indicate also that
measures taken to arrest galloping of guy cables should not rely on any single
mechanism of aerodynamic instability.
| Original language | English |
|---|---|
| Qualification | Doctor Degree |
| Awarding Institution |
|
| Award date | 26 Oct 1984 |
| Place of Publication | Espoo |
| Publisher | |
| Print ISBNs | 951-38-2005-X |
| Publication status | Published - 1984 |
| MoE publication type | G4 Doctoral dissertation (monograph) |
Keywords
- guys
- vibration
- aeroelasticity
- mathematical models
- ice
- wind pressure
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Cite this
Kärnä, T. (1984). Dynamic and aeroelastic action of guy cables: Dissertation. VTT Technical Research Centre of Finland.