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Behavior of self supported transmission line towers under stationary downburst loading
Darwish, Mohamed M.,El Damatty, Ashraf A. Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.5
During the past decade, many electrical transmission tower structures have failed during downburst events. This study is a part of a research program aimed to understand the behaviour of transmission lines under such localized wind events. The present study focuses on assessing the behaviour of self supported transmission line towers under downburst loading. A parametric study is performed to determine the critical downburst configurations causing maximum axial forces for various members of a tower. The sensitivity of the internal forces developing in the tower's members to changes in the downburst size and location was studied. The structural behaviour associated with the critical downburst configurations is described and compared to the behaviour under 'normal' wind loads.
Behavior of self supported transmission line towers under stationary downburst loading
Mohamed M. Darwish,Ashraf A. El Damatty 한국풍공학회 2011 Wind and Structures, An International Journal (WAS Vol.14 No.5
During the past decade, many electrical transmission tower structures have failed during downburst events. This study is a part of a research program aimed to understand the behaviour of transmission lines under such localized wind events. The present study focuses on assessing the behaviour of self supported transmission line towers under downburst loading. A parametric study is performed to determine the critical downburst configurations causing maximum axial forces for various members of a tower. The sensitivity of the internal forces developing in the tower’s members to changes in the downburst size and location was studied. The structural behaviour associated with the critical downburst configurations is described and compared to the behaviour under ‘normal’ wind loads.
Mohamed M. Darwish,Ashraf A. El Damatty,Horia Hangan 한국풍공학회 2010 Wind and Structures, An International Journal (WAS Vol.13 No.4
During the past decade, many electrical transmission tower structures have failed during downburst events. This study is a part of a research program aimed to understand the behaviour of transmission lines under such localized wind events. The present study focuses on the assessment of the dynamic behaviour of the line conductors under downburst loading. A non-linear numerical model, accounting for large deformations and the effect of pretension loading, is developed and used to predict the natural frequencies and mode shapes of conductors at various loading stages. A turbulence signal is extracted from a set of full-scale data. It is added to the mean component of the downburst wind field previously evaluated from a CFD analysis. Dynamic analysis is performed using various downburst configurations. The study reveals that the response is affected by the background component, while the resonant component turns to be negligible due large aerodynamic damping of the conductors.
Darwish, Mohamed M.,El Damatty, Ashraf A.,Hangan, Horia Techno-Press 2010 Wind and Structures, An International Journal (WAS Vol.13 No.4
During the past decade, many electrical transmission tower structures have failed during downburst events. This study is a part of a research program aimed to understand the behaviour of transmission lines under such localized wind events. The present study focuses on the assessment of the dynamic behaviour of the line conductors under downburst loading. A non-linear numerical model, accounting for large deformations and the effect of pretension loading, is developed and used to predict the natural frequencies and mode shapes of conductors at various loading stages. A turbulence signal is extracted from a set of full-scale data. It is added to the mean component of the downburst wind field previously evaluated from a CFD analysis. Dynamic analysis is performed using various downburst configurations. The study reveals that the response is affected by the background component, while the resonant component turns to be negligible due large aerodynamic damping of the conductors.
Atef S. Darwish,Mohamed A. Mekewi,Tarek M. Madkour,Youmna M. Hashish 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.30 No.-
This work focused on designing three-categorized polymeric forms; carboxylic-enriched, amideenrichedand equi-rationed amide-carboxylic hydrogels. Such hydrogels were analyzed using swelling,Monte-Carlo simulations, TGA, zeta-potential measurements, SEM and AFM. Their adsorption behaviorswere examined using methylene blue dye. Effect of pH, adsorption isotherms, kinetics, temperature andadsorbent reproducibility were deliberated. All adsorption processes described by Dubinin–Radushkevichmodel following pseudo-second order kinetics. Carboxylic-enriched hydrogel showed negativelychargedsmooth surfaces with unusual ulcer-like holes, which played the chief role in dyeing removalfrom wastewater with superior reproducibility. Increasing amide ratios in hydrogels encouragedelectrostatic and chemical interactions with dye molecules and deteriorated adsorbent reproducibility.