Safety of power transmission line structures under wind and ice storms

Kudzys, Antanas

doi:10.1016/j.engstruct.2005.09.026

Cited by 42 publications

(23 citation statements)

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“…For the telecommunication and power line industry, cables are usually of very small diameter. Furthermore, even though several studies involving real and simulated ice accretions on circular power lines have been reported (Nigol and Clarke 1974, Hack 1981, Nigol and Buchan 1981, Jamaleddine et al 1993, McComber and Paradis 1995, Chabart and Lilien 1998, Gurung et al 2002, Phuc 2005, Shimizu 2005, Kudzys 2006, Fo-chi et al 2009, Dalle and Admirat 2010, Wang et al 2010, the meteorological conditions associated with these cases differ from the situations in which large bridge cable vibrations have been reported.…”

Section: Introductionmentioning

confidence: 81%

An evaluation of iced bridge hanger vibrations through wind tunnel testing and quasi-steady theory

Gjelstrup¹,

Georgakis²,

Larsen³

2012

Wind and Structures An International Journal

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Abstract. Bridge hanger vibrations have been reported under icy conditions. In this paper, the results from a series of static and dynamic wind tunnel tests on a circular cylinder representing a bridge hanger with simulated thin ice accretions are presented. The experiments focus on ice accretions produced for wind perpendicular to the cylinder at velocities below 30 m/s and for temperatures between −5°C and -1°C. Aerodynamic drag, lift and moment coefficients are obtained from the static tests, whilst mean and fluctuating responses are obtained from the dynamic tests. The influence of varying surface roughness is also examined. The static force coefficients are used to predict parameter regions where aerodynamic instability of the iced bridge hanger might be expected to occur, through use of an adapted theoretical 3-DOF quasi-steady galloping instability model, which accounts for sectional axial rotation. A comparison between the 3-DOF model and the instabilities found through two degree-of-freedom (2-DOF) dynamic tests is presented. It is shown that, although there is good agreement between the instabilities found through use of the quasi-steady theory and the dynamic tests, discrepancies exist-indicating the possible inability of quasi-steady theory to fully predict these vibrational instabilities.

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Section: Introductionmentioning

confidence: 81%

An evaluation of iced bridge hanger vibrations through wind tunnel testing and quasi-steady theory

Gjelstrup¹,

Georgakis²,

Larsen³

2012

Wind and Structures An International Journal

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“…Because of the stochastic nature of ice storms and difficulties in predicting their occurrence, most past investigations of freezing rain and ice across this region have been done for (1) case studies of major storms (e.g., Bruederle and Stearns 1985;Rebertus et al 1997;Rhoads et al 2002), (2) assessment of the risk of icing to specific facilities such as buildings, wires, or aircraft (e.g., Hoffmann 1984;Jones 1996Jones , 1998Kudzys 2006), and (or) (3) research relating to the forecasting of freezing-rain conditions (e.g., Changnon 2003;Cheng et al 2004Cheng et al , 2011. Few studies have had the opportunity to focus on a robust suite of ecological effects in natural ecosystems.…”

Section: Ice Stormsmentioning

confidence: 99%

A novel ice storm manipulation experiment in a northern hardwood forest

Rustad

Campbell

2012

Can. J. For. Res.

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Ice storms are an important natural disturbance within forest ecosystems of the northeastern United States. Current models suggest that the frequency and severity of ice storms may increase in the coming decades in response to changes in climate. Because of the stochastic nature of ice storms and difficulties in predicting their occurrence, most past investigations of the ecological effects of ice storms across this region have been based on case studies following major storms. Here we report on a novel alternative approach where a glaze ice event was created experimentally under controlled conditions at the Hubbard Brook Experimental Forest, New Hampshire, USA. Water was sprayed over a northern hardwood forest canopy during February 2011, resulting in 7-12 mm radial ice thickness. Although this is below the minimum cutoff for ice storm warnings (13 mm of ice) issued by the US National Weather Service for the northeastern United States, this glaze ice treatment resulted in significant canopy damage, with 142 and 218 g C·m -2 of fine and coarse woody debris (respectively) deposited on the forest floor, a significant increase in leaf-on canopy openness, and increases in qualitative damage assessments following the treatment. This study demonstrates the feasibility of a relatively simple approach to simulating an ice storm and underscores the potency of this type of extreme event in shaping the future structure and function of northern hardwood forest ecosystems.Résumé : Les tempêtes de verglas sont la cause d'une perturbation naturelle importante dans les écosystèmes forestiers du nord-est des États-Unis. Les modèles actuels indiquent que la fréquence et la sévérité des tempêtes de verglas pourraient augmenter au cours de la prochaine décennie en réaction aux changements climatiques. Parce que les tempêtes de verglas sont par nature aléatoire et que leur occurrence est difficile à prédire, la plupart des travaux de recherche passés portant sur les effets écologiques des tempêtes de verglas dans cette région ont été basés sur des études de cas à la suite de tempêtes majeures. Cette étude porte sur une approche alternative originale qui consiste à produire expérimentalement dans des conditions contrôlées un épisode de verglas à la forêt expérimentale de Hubbard Brook, au New Hampshire, É.-U. La canopée d'une forêt de feuillus nordiques a été arrosée avec de l'eau en février 2011 provoquant la formation de glace dont l'épais-seur radiale a atteint 7 à 12 mm. Bien que cela soit sous le seuil minimal (13 mm de glace) pour que le Service météorolo-gique nationale des États-Unis lance un avis de tempête de verglas pour le nord-est des États-Unis, ce traitement a provoqué des dommages importants entraînant le dépôt sur la couverture morte de respectivement 142 et 218 g C·m -2 de débris ligneux fins et grossiers, une augmentation significative de l'ouverture de la canopée feuillue et des augmentations dans les évaluations des dommages qualitatifs à la suite du traitement. Cette étude démontre la faisabilité d'une approche r...

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“…Since 1950, to handle the frequent ice storm, experts and scholars from both institutions and companies have carried out special studies on ice melting for transmission lines and a lot of models for solving IMT have been established [2], [5], [6].…”

Section: Introductionmentioning

confidence: 99%

Simulation and Experimental Investigation of DC Ice-Melting Process on an Iced Conductor

Jiang

Fan

Zhang

et al. 2010

IEEE Trans. Power Delivery

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Ice melting with dc is one of the key technologies to prevent the Chinese power grid from ice storms. Especially after the severe ice storm in the southern part of China in early 2008, dc ice-melting technology has drawn more attention than ever before. However, there are few satisfactory methods to select correct parameters so the ice-melting project rarely achieves desired effects in some cases when applied in Hunan, Guizhou, and other provinces in China. Therefore, it is of great significance to develop a method to estimate parameters which is applicable in the practical situation for dc ice melting. To handle this, the factors, such as wind velocity, ambient temperature, current density and ice-layer thickness were analyzed and then a dc ice-melting model is put forward in this paper. Both the results of simulations and experiments show that the ice-melting process can be divided into three stages composed of temperature rising, ice melting, and ice shedding, among which the ice melting is the key stage consuming most of the ice-melting time. In this stage, an elliptic airgap is formed and widened gradually with an influence on the ice-melting time and the temperature of the conductor. The experiments in the artificial climate chamber demonstrate that the results of the presented model are consistent with those of the experiments generally, so it can be employed to estimate the parameters of ice melting in practical engineering as reference.

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Safety of power transmission line structures under wind and ice storms

Cited by 42 publications

References 1 publication

An evaluation of iced bridge hanger vibrations through wind tunnel testing and quasi-steady theory

An evaluation of iced bridge hanger vibrations through wind tunnel testing and quasi-steady theory

A novel ice storm manipulation experiment in a northern hardwood forest

Simulation and Experimental Investigation of DC Ice-Melting Process on an Iced Conductor

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