Theoretical and experimental study of coupled rocking-swivelling model of guyed mast shaft

0453087 - ÚTAM 2016 CH eng A - Abstrakt
Urushadze, Shota - Pirner, Miroš - Fischer, Ondřej
Theoretical and experimental study of coupled rocking-swivelling model of guyed mast shaft.
EVACES'15. International conference on experimental vibration analysis for civil engineering structures. Dübendorf: EMPA, 2015 - (Feltrin, G.). s. 27-27. ISBN N.
[International Conference on Experimental Vibration Analysis for Civil Engineering Structures. 19.10.2015-21.10.2015, Dübendorf]
Grant CEP: GA ČR(CZ) GC13-34405J
Institucionální podpora: RVO:68378297
Klíčová slova: guyed mast shaft * swivelling * wind-excited vibration
Kód oboru RIV: JM - Inženýrské stavitelství

Systematic monitoring of torsion (swivelling) of guyed mast shafts has been performed in ITAM since 2005. The occurence of this phenomenon is conditioned by the fact that the guy ropes are attached to the surface of the shaft, i.e. out of its axis. The simple static calculation model serves for making the proof of the occurence of the moment, affecting the shaft, which is guyed by three ropes. The exact theoretical solution of the real phenomenon assumes the introduction of dynamics of guy ropes, which vibrate in 3D shapes during the shaft's movement along the orbit and it's torsion (swivelling). As well as a detailed determination of the aerodynamic characteristic of the shaft cross-section with respect to the conditions of aerodynamic instability. In more detail and more stable aerodynamic conditions was the phenomenon of swivelling of the mast shaft examined on simple model. The shaft was a tube of hardened PVC, of an outer diameter of 75 mm, supported by a point at the bottom guyed by three wires in one level. The out of axis was changed for its influence estimation. The flexural rigidity of the shaft is not modelled; the bending is substituted by the tilting. That is why there are no higher shapes of tilting and the orbit is always close to ellipse. The torsion was verified in a wind tunnel. The experiment have been performed in the new aerodynamic tunnel (ITAM- Telč). Wind tunnel section size enabled experiment with model shaft up to 1500 mm high, anchored by three ropes at a height of 1000 mm. The top end of the shaft was equipped with a horizontal arm two accelerometers attached on its ends; the distance between the accelerometers in 380 mm. Accelerometers 1 and 2 sense the motion ion the direction perpendicular to the horizontal arm. Besides the two accelerometers on the horizontal arm there is also the third accelerometer at the upper end of the shaft, which senses the motion perpendicular to the direction of the above pair of accelerometers.
Trvalý link: http://hdl.handle.net/11104/0253977