Documents disponibles écrits par cet auteur

Anatomy of turbulence effects on the aerodynamics of an oscillating prism / Haan, F. L. Jr. in Journal of engineering mechanics, Vol. 135 N° 9 (Septembre 2009) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 135 N° 9 (Septembre 2009) . - pp. 987-999 Titre : Anatomy of turbulence effects on the aerodynamics of an oscillating prism Type de document : texte imprimé Auteurs : Haan, F. L. Jr., Auteur ; Ahsan Kareem, Auteur Article en page(s) : pp. 987-999 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Aerodynamics  Prism  Aeroelasticity  Flutter  Turbulence  Fluid-structure  interaction  Bridges  Load  factors. Résumé : Turbulence-induced changes in aerodynamic force characteristics on an oscillating rectangular prism were investigated in this study. It encompassed examination of aeroelastic quantities, i.e., flutter derivatives, and the buffeting components of the integral forces. A forced-vibration system was employed to extract the aerodynamic characteristics of an oscillating prism using a model instrumented with multiple pressure transducers for synchronous scanning of the pressure field. Chordwise distributions of self-excited pressure amplitudes were measured and associated phases were derived to examine the anatomy of turbulence effects on the aerodynamics of the prism rather than simply discern the influence of turbulence on the integrated forces. The resulting changes in flutter derivatives were traced back to a turbulence-induced upstream shifting of the regions of maximum pressure amplitudes. This upstream shifting was consistent with earlier research showing that turbulence increases the radius of curvature of separated shear layers and moves reattachment upstream. In this study, turbulence was found to have a stabilizing effect on the aerodynamics of the prism. The broad band character of the buffeting forces was found to be quite similar to that of stationary prisms with body motion slightly increasing energy content. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...] [article] Anatomy of turbulence effects on the aerodynamics of an oscillating prism [texte imprimé] / Haan, F. L. Jr., Auteur ; Ahsan Kareem, Auteur . - pp. 987-999. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 9 (Septembre 2009) . - pp. 987-999 Mots-clés : Aerodynamics  Prism  Aeroelasticity  Flutter  Turbulence  Fluid-structure  interaction  Bridges  Load  factors. Résumé : Turbulence-induced changes in aerodynamic force characteristics on an oscillating rectangular prism were investigated in this study. It encompassed examination of aeroelastic quantities, i.e., flutter derivatives, and the buffeting components of the integral forces. A forced-vibration system was employed to extract the aerodynamic characteristics of an oscillating prism using a model instrumented with multiple pressure transducers for synchronous scanning of the pressure field. Chordwise distributions of self-excited pressure amplitudes were measured and associated phases were derived to examine the anatomy of turbulence effects on the aerodynamics of the prism rather than simply discern the influence of turbulence on the integrated forces. The resulting changes in flutter derivatives were traced back to a turbulence-induced upstream shifting of the regions of maximum pressure amplitudes. This upstream shifting was consistent with earlier research showing that turbulence increases the radius of curvature of separated shear layers and moves reattachment upstream. In this study, turbulence was found to have a stabilizing effect on the aerodynamics of the prism. The broad band character of the buffeting forces was found to be quite similar to that of stationary prisms with body motion slightly increasing energy content. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...]

Tornado-induced wind loads on a low-rise building / Haan, F. L. Jr. in Journal of structural engineering, Vol. 136 N° 1 (Janvier 2010) 

Public ISBD [article]  in Journal of structural engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 106-116 Titre : Tornado-induced wind loads on a low-rise building Type de document : texte imprimé Auteurs : Haan, F. L. Jr., Auteur ; Vasanth Kumar Balaramudu, Auteur ; P. P. Sarkar, Auteur Année de publication : 2011 Article en page(s) : pp. 106-116 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Tornado  Wind  engineerin  Low-rise  buildings  Bluff-body  aerodynamics  Wind  hazards Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Current design wind loads for buildings and other structures are based upon model tests in low-speed boundary-layer wind tunnels that generate straight-line winds. Winds resulting from tornadoes that can occur during extreme weather events such as thunderstorms or hurricanes differ greatly from conventionally conceived atmospheric boundary-layer winds. This paper presents transient wind loads on a one-story, gable-roofed building in a laboratory-simulated tornado and compares them with the provisions of building standards. Tornadoes were simulated in smooth, open terrain with vortex core diameters from roughly five to twelve times the plan dimension of the building model (0.46 to 1.06 m). A 1:100 scale model of a building with dimensions of 9.1 m×9.1 m×6.6 m and gable roof angle of 35° was used for this study. Comparisons of peak loads measured in this study showed that tornado-like vortices can generate load coefficients greater than those prescribed by ASCE 7-05 for straight-line wind over open terrain. For lateral forces, these coefficients were found to be as much as 50% larger than the standard provisions. Vertical uplift coefficients were found to be two to three times the provisions most likely due to the effect of a large negative static pressure generated at the core of the vortex. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i1/p106_s1?isAuthorized=no [article] Tornado-induced wind loads on a low-rise building [texte imprimé] / Haan, F. L. Jr., Auteur ; Vasanth Kumar Balaramudu, Auteur ; P. P. Sarkar, Auteur . - 2011 . - pp. 106-116. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 106-116 Mots-clés : Tornado  Wind  engineerin  Low-rise  buildings  Bluff-body  aerodynamics  Wind  hazards Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Current design wind loads for buildings and other structures are based upon model tests in low-speed boundary-layer wind tunnels that generate straight-line winds. Winds resulting from tornadoes that can occur during extreme weather events such as thunderstorms or hurricanes differ greatly from conventionally conceived atmospheric boundary-layer winds. This paper presents transient wind loads on a one-story, gable-roofed building in a laboratory-simulated tornado and compares them with the provisions of building standards. Tornadoes were simulated in smooth, open terrain with vortex core diameters from roughly five to twelve times the plan dimension of the building model (0.46 to 1.06 m). A 1:100 scale model of a building with dimensions of 9.1 m×9.1 m×6.6 m and gable roof angle of 35° was used for this study. Comparisons of peak loads measured in this study showed that tornado-like vortices can generate load coefficients greater than those prescribed by ASCE 7-05 for straight-line wind over open terrain. For lateral forces, these coefficients were found to be as much as 50% larger than the standard provisions. Vertical uplift coefficients were found to be two to three times the provisions most likely due to the effect of a large negative static pressure generated at the core of the vortex. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i1/p106_s1?isAuthorized=no