An investigation of rain-wind induced vibrations on stay cables in a novel range of operating conditions
Notice bibliographique
Résumé
The large-scale rain-wind induced vibration (RWIV) dynamic test rig at the National Research Council Canada (NRC) was used in the current work to evaluate the vibration characteristics of a 0.218 m diameter smooth stay cable, for two cable inclinations and a wide range of yaw-angle conditions. The structural damping ratio was in the range of 0.05% to 0.11% and the heave frequency was approximately 1.23 Hz for a cable with a moving mass of 217 kg. The presence of RWIV was investigated at an inclination angle of 30° from the horizontal over a yaw-angle range of 25° to 45° and for an inclination angle of 55° over a yaw-angle range of −40° to ＋45°. An upper rivulet was present when vibrations were observed. For positive yaw angles, the upper rivulet was characterized by a thin line of water, approximately 5 to 10 mm wide, running along the entire length of the inclined cable on the windward side and moving along the cable span with a serpentine motion. For negative yaw angles, the upper rivulet was located near top of the cable or on the leeward sector of the cable, was wider than the rivulets observed for positive yaw angles, and was not observed to move in a serpentine motion. RWIVs were observed for each yaw angle that was investigated, including at negative yaw angles, with a maximum amplitude of motion of ±150 mm (∼0.7D). The direction of the rain impingement was an important factor affecting the formation and characteristics of the upper rivulet at the surface of the cable and, for the onset for vibrations. RWIVs were observed for wind speeds between 5 and 12 m/s. The Reynolds number corresponding to the onset of RWIV tended to increase with larger yaw angles in the positive yaw-angle range. At an inclination angle of 30°, the onset of RWIV ranged from 1.2×105 at a yaw of 25° to 1.4×105 at a yaw of 45° while at a cable inclination angle of 55°, the onset of RWIV ranged from 1.08×105 at a yaw of 25° to 1.25×105 at a yaw of 40°. The onset of vibrations for a yaw angle of 0° was at 0.77×105 for a cable inclination of 55°. RWIV was initiated at lower Reynolds numbers at an inclination angle of 55° for negative yaw angles, with vibrations observed at wind speeds as low as 5 m/s (Reynolds number of 0.7×105). The results confirmed the presence of RWIV in well-understood conditions and have effectively expanded the range of conditions over which RWIV has been observed in a wind tunnel. The expanded range over which RWIV was observed includes vibrations at an inclination angle of 55°, vibrations at a yaw angle of 0°, and vibrations at negative yaw angles from −10° to −40°.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».