Effect of icing on the free vibration of guyed antenna towers

Wahba, Yohanna M. F.; Madugula, Murty K. S.; Monforton, Gerard R.

doi:10.1016/s0169-8095(97)00048-3

Cited by 10 publications

(6 citation statements)

References 2 publications

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“…The effect of rain associated with wind has been studied mostly in the cables of long bridges [ 18 ], but in a short bridge it could have played a minor role only. Ice plays an important role various structures because it tends to reduce their modal frequencies [ 19 ], but in the study bridge, which is in a location in which temperatures are always above 2–3 °C (and hence various structures are unprotected to ice effects), the role of an icing event may be critical.…”

Section: Possible Causes Of Asymmetric Damagementioning

confidence: 99%

Wind-Induced Fatigue and Asymmetric Damage in a Timber Bridge

Thalla

Stiros

2018

Sensors

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The transformation of a 30 m long timber pedestrian bridge into a wobbly (laterally swaying) bridge with a dramatically reduced first lateral modal frequency has been monitored by seven annual, multi-sensor surveys. This evidence, in combination with analysis of the wind record, observations of local damage and evidence of wind-induced excitations from other bridges, is used to present a multi-stage scenario of the extraordinary structural weakening of our study bridge in only a few years. Our analysis is constrained by observations of asymmetric damage (longitudinal splitting cracks around metallic connections along the south side of the deck, not explained by ordinary, essentially symmetric lateral oscillations) and over-threshold analysis of strong northerly wind events, including gusts. The proposed scenario is that an unexpected for the area icing event took advantage of construction vicissitudes and produced damage that reduced the lateral stiffness of the bridge, especially of the arch superstructure. In addition, strong winds sharing common direction with gusts produced a combination of semi-static lateral bending and of dynamic oscillations, leading to numerous cycles of asymmetric high amplitude lateral deflections producing tensile stress normal to grain, cracks localized in connections, and fatigue. The vertical stiffness of the bridge was only slightly affected.

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Section: Possible Causes Of Asymmetric Damagementioning

confidence: 99%

Wind-Induced Fatigue and Asymmetric Damage in a Timber Bridge

Thalla

Stiros

2018

Sensors

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“…It is fair to ABCM mention the investigations made by: Kitipornchai 1993 and2003;Albermani et al 2004;Carril Júnior 2000;ElGhazaly and Al-Khaiat 1995;Kahla 1994, Kitipornchai and Albermani 1992Madugula and Wahba 1998;Menin 2002, Rao andKalyanaraman 2001;Saxena et al 1989;Wahba et al 1996. Kahla 1994, numerically modelled the dynamical effects present in guyed steel towers including the cable galloping effects.…”

Section: The Structural Modellingmentioning

confidence: 99%

Structural analysis of guyed steel telecommunication towers for radio antennas

Oliveira¹,

Silva²,

Vellasco³

et al. 2007

J. Braz. Soc. Mech. Sci. & Eng.

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“…The Structural Modeling by Several authors have contributed with theoretical and experimental investigations to access the best modeling strategy for steel transmission and telecommunication towers. It is fair to mention the investigations made by: Albermani et al 2004 [10]; Carril Junior 2000 [11]; El-Ghazaly and Al-Khaiat 1995 [12]; Kahla 1994[13] and 2000 [14], Kitipornchaiand Albermani 1992[15]; Madugula and Wahba 1998[16]; Menin 2002[17], Raoand Kalyanaraman 2001 [18]; Saxena et al 1989 [19]; Wahba et al 1996 [20] andWahba et al 1998 [21]. Kahla 1994[13], numerically modelled the dynamical effects present in guyed steel towers including the cable galloping effects.…”

Section: Introductionmentioning

confidence: 99%

“…Later the same author, Kahla 2000[14], dynamically modelled the rupture of acable present in guyed steel towers. The analysis indicated that the guyed steel towers cable rupture, disregarding the wind actions, was one of the most severe critical load hypotheses for the investigatedstructures .Wahba et al 1996 [20], considered the dynamical nature of the load acting in guyed steel towers like wind, earthquakes and cable gallop.…”

Section: Introductionmentioning

confidence: 99%

Numerical solution of base shear in high tensioned cable antenna

Sadrnejad

2016

NMCE

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A finite element solution based on equevalent elements is proposed for the static and dynamic analysis of tallhigh tensioned cable antennas. To reduce high number of degrees of freedom in space frame body of a structure, a simple equivalent beam element is defined for each simulative substructure. This numerical procedure is applicable to analyze complex three dimensional assemblies of substructures of such similar complex structures. In this analysis wind pressure effects accompanied by change of postentioning loads in nonlinear cable elements, earthquake effects, and any other arbitrary loads on the substructures. Accordingly, the restriction of the loads on the cable elements to gravity and thermal loads can be applied. The algorithm is developed upon an efficient cable elements depending on the given position and curved geometry of the cable, its end forces, and its tangent stiffness matrix. The employed formulation scheme permits any magnitude of deformation for straight or curved elements. The postensioning stresses in cables were considered as initial stresses. To simulate the equevalent elements, both ends stiffness, damping and mass components are calibrated to present the same static and dynamic responses as the selected substructure. To simulate dynamic responses, the equevalent single mass matrix and its adjusted position are carried out to obtain the same frequencies in equevalent elements. The static solution of a complete structure compared well with the results presented by simulated model. This paper proposes an alternative structural analysis modeling strategy for guyed steel towers design, considering all the equivalent structural forces and moments, by using threedimensional beam finite elements. Comparisons of the above mentioned design models with an alternative, that models the main structure and the bracing system with 3D beam finite elements, are made for existing guyed steel telecommunication towers (325m high). The comparisons are initially based on the towers static and dynamic structural behavior later to be followed by a linear buckling analysis to determine the influence of the various modeling strategies on the tower stability behaviour. d

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Effect of icing on the free vibration of guyed antenna towers

Cited by 10 publications

References 2 publications

Wind-Induced Fatigue and Asymmetric Damage in a Timber Bridge

Wind-Induced Fatigue and Asymmetric Damage in a Timber Bridge

Structural analysis of guyed steel telecommunication towers for radio antennas

Numerical solution of base shear in high tensioned cable antenna

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