Documents disponibles écrits par cet auteur

High-rise reinforced concrete structures / DongHun Yeo in Journal of structural engineering, Vol. 137 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1340-1349 Titre : High-rise reinforced concrete structures : Database-assisted design for wind Type de document : texte imprimé Auteurs : DongHun Yeo, Auteur ; Simiu, Emil, Auteur Année de publication : 2012 Article en page(s) : pp. 1340-1349 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Database-assisted  design  (DAD)  Mean  recurrence  interval  Reinforced  concrete  Time-domain  analysis  Wind  effects Résumé : Advances in wind pressure measurement and computer technology have made time-domain analyses of wind effects on high-rise structures possible in recent years. Time-domain solutions use aerodynamic and wind climatological databases and provide full phase information on wind-induced response that is lost in the frequency-domain approach; therefore, they can account rigorously for the superposed effects of any number of modes of vibration of any shape; for mode coupling; for wind directionality effects; and for the joint contributions of axial forces, bending moments, and shear forces in interaction equations used for structural design. Unlike the frequency-domain approach, in the time-domain approach, the process of determining wind effects and the structural design process, referred to jointly as database-assisted design (DAD), are integrated, transparent, and fully auditable. The objective of this study is to present the DAD approach as applied to high-rise reinforced concrete (RC) buildings. Given the time histories of pressures, measured in the wind tunnel at a sufficient number of taps on the exterior faces of the building envelope for a sufficient number of mean speed directions and a preliminary design of the building, the structural engineer can calculate, as functions of wind speed and direction: (1) demand-to-capacity indexes for any number of members and cross sections, (2) interstory drift, (3) and top floor accelerations. These responses are properties of the structure independent of the wind climate, and constitute response databases used in conjunction with a wind climatological database to obtain the requisite wind effects for any specified mean recurrence interval. The design, which accounts for both wind and gravity effects, is performed iteratively until the design specifications are satisfied. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i11/p1340_s1?isAuthorized=no [article] High-rise reinforced concrete structures : Database-assisted design for wind [texte imprimé] / DongHun Yeo, Auteur ; Simiu, Emil, Auteur . - 2012 . - pp. 1340-1349. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1340-1349 Mots-clés : Database-assisted  design  (DAD)  Mean  recurrence  interval  Reinforced  concrete  Time-domain  analysis  Wind  effects Résumé : Advances in wind pressure measurement and computer technology have made time-domain analyses of wind effects on high-rise structures possible in recent years. Time-domain solutions use aerodynamic and wind climatological databases and provide full phase information on wind-induced response that is lost in the frequency-domain approach; therefore, they can account rigorously for the superposed effects of any number of modes of vibration of any shape; for mode coupling; for wind directionality effects; and for the joint contributions of axial forces, bending moments, and shear forces in interaction equations used for structural design. Unlike the frequency-domain approach, in the time-domain approach, the process of determining wind effects and the structural design process, referred to jointly as database-assisted design (DAD), are integrated, transparent, and fully auditable. The objective of this study is to present the DAD approach as applied to high-rise reinforced concrete (RC) buildings. Given the time histories of pressures, measured in the wind tunnel at a sufficient number of taps on the exterior faces of the building envelope for a sufficient number of mean speed directions and a preliminary design of the building, the structural engineer can calculate, as functions of wind speed and direction: (1) demand-to-capacity indexes for any number of members and cross sections, (2) interstory drift, (3) and top floor accelerations. These responses are properties of the structure independent of the wind climate, and constitute response databases used in conjunction with a wind climatological database to obtain the requisite wind effects for any specified mean recurrence interval. The design, which accounts for both wind and gravity effects, is performed iteratively until the design specifications are satisfied. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i11/p1340_s1?isAuthorized=no

Multiple points-in-time estimation of peak wind effects on structures / DongHun Yeo in Journal of structural engineering, Vol. 139 N° 3 (Mars 2013) 

Public ISBD [article]  in Journal of structural engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 462–471 Titre : Multiple points-in-time estimation of peak wind effects on structures Type de document : texte imprimé Auteurs : DongHun Yeo, Auteur Année de publication : 2013 Article en page(s) : pp. 462–471 Note générale : structural engineering Langues : Anglais (eng) Mots-clés : wind  loads;  structural  response;  high-rise  buildings;  concrete  structures;  reinforced  concrete Résumé : One of the problems encountered in the estimation of wind effects on high-rise structures is the development of combinations of wind-induced translational responses in possible conjunction with rotational responses and/or of forces and moments that contribute to the wind-induced demand at various cross sections of individual structural members. In current wind engineering practice such combinations are developed in large part intuitively because phase information on the effects being combined is not readily available from frequency domain analyses. In contrast, full time series analyses can produce estimates of combined wind effects because they preserve phase information; however, such analyses can be overly time-consuming. In current wind engineering practice it is common to use the empirical point-in-time (PIT) procedure for the estimation of peaks of combined stationary stochastic processes. The procedure is applied to pairs of such processes, and consists of adding an estimate of the peak value of one of the processes to the estimated value of the second process at the time of the occurrence of that peak. Even if the full time histories of the two stochastic processes are used, errors inherent in PIT can be in some cases as high as 20% on the unconservative side. The purpose of this paper is to present the empirical multiple points-in-time (MPIT) procedure, which improves significantly upon the PIT approach. The MPIT procedure is illustrated by an application to a 60-story reinforced concrete structure. Results show that the MPIT approach produces remarkably accurate estimates of the peak combined wind effects by using a limited number of peaks from the time histories of the individual wind effects being combined. Those estimates are obtained far more economically in terms of computational time than conventional time domain estimates that use full time histories. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000649 [article] Multiple points-in-time estimation of peak wind effects on structures [texte imprimé] / DongHun Yeo, Auteur . - 2013 . - pp. 462–471. structural engineering Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 462–471 Mots-clés : wind  loads;  structural  response;  high-rise  buildings;  concrete  structures;  reinforced  concrete Résumé : One of the problems encountered in the estimation of wind effects on high-rise structures is the development of combinations of wind-induced translational responses in possible conjunction with rotational responses and/or of forces and moments that contribute to the wind-induced demand at various cross sections of individual structural members. In current wind engineering practice such combinations are developed in large part intuitively because phase information on the effects being combined is not readily available from frequency domain analyses. In contrast, full time series analyses can produce estimates of combined wind effects because they preserve phase information; however, such analyses can be overly time-consuming. In current wind engineering practice it is common to use the empirical point-in-time (PIT) procedure for the estimation of peaks of combined stationary stochastic processes. The procedure is applied to pairs of such processes, and consists of adding an estimate of the peak value of one of the processes to the estimated value of the second process at the time of the occurrence of that peak. Even if the full time histories of the two stochastic processes are used, errors inherent in PIT can be in some cases as high as 20% on the unconservative side. The purpose of this paper is to present the empirical multiple points-in-time (MPIT) procedure, which improves significantly upon the PIT approach. The MPIT procedure is illustrated by an application to a 60-story reinforced concrete structure. Results show that the MPIT approach produces remarkably accurate estimates of the peak combined wind effects by using a limited number of peaks from the time histories of the individual wind effects being combined. Those estimates are obtained far more economically in terms of computational time than conventional time domain estimates that use full time histories. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000649

Simplified wind flow model for the estimation of aerodynamic effects on small structures / DongHun Yeo in Journal of engineering mechanics, Vol. 139 N° 3 (Mars 2013) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 139 N° 3 (Mars 2013) . - pp.367–375. Titre : Simplified wind flow model for the estimation of aerodynamic effects on small structures Type de document : texte imprimé Auteurs : DongHun Yeo, Auteur ; Arindam Gan Chowdhury, Auteur Année de publication : 2013 Article en page(s) : pp.367–375. Note générale : Applied mechanics Langues : Anglais (eng) Mots-clés : Atmospheric  boundary  layer  Computational  wind  engineering  Flow  modeling  Low-rise  buildings  Wind  engineering  Wind  tunnel  tests Résumé : The reliable measurement of pressures on low-rise buildings in the atmospheric boundary layer (ABL) flow remains a challenge, as has been shown by the large discrepancies among results obtained in different wind tunnel facilities or even in the same wind tunnel. Two major causes of the discrepancies are the difficulty of simulating large-scale, low-frequency turbulent fluctuations uniformly across laboratories and the small scale of models in typical civil engineering wind tunnels. To address these issues, it was proposed that a simplified flow be used in laboratory simulations, rather than a conventional ABL flow. In the simplified flow the reference mean wind speed is larger than the mean wind speed of the ABL flow, and the low-frequency fluctuations present in the ABL flow are suppressed; that is, the peak energy of the missing low-frequency fluctuations is supplied in the simplified flow by the increment in the mean wind speed, which may be regarded as a flow fluctuation with zero frequency. High-frequency turbulent fluctuations, which typically affect flow reattachment, are approximately the same in the ABL and the simplified flow. Because, over small distances, low-frequency fluctuations are highly coherent spatially for small low-rise buildings with dimensions of up to approximately 20 m (e.g., single-family residential homes), the peak aerodynamic effects of the two flows may be hypothesized to be approximately the same. Preliminary experimental results obtained in University of Western Ontario’s ABL wind tunnel facility and Florida International University’s small-scale Wall of Wind facility are shown to support this hypothesis. The use of the proposed simplified flow is currently being tested by the authors for application to computational wind engineering (CWE) applications. Such use eliminates the need to simulate the lower frequency fluctuations of the boundary layer flow and thus makes it possible to achieve practical CWE calculations, and it is advantageous in experiments from the points of view of measurement accuracy, model scaling, repeatability of the simulations, and computational efficiency. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000508 [article] Simplified wind flow model for the estimation of aerodynamic effects on small structures [texte imprimé] / DongHun Yeo, Auteur ; Arindam Gan Chowdhury, Auteur . - 2013 . - pp.367–375. Applied mechanics Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 139 N° 3 (Mars 2013) . - pp.367–375. Mots-clés : Atmospheric  boundary  layer  Computational  wind  engineering  Flow  modeling  Low-rise  buildings  Wind  engineering  Wind  tunnel  tests Résumé : The reliable measurement of pressures on low-rise buildings in the atmospheric boundary layer (ABL) flow remains a challenge, as has been shown by the large discrepancies among results obtained in different wind tunnel facilities or even in the same wind tunnel. Two major causes of the discrepancies are the difficulty of simulating large-scale, low-frequency turbulent fluctuations uniformly across laboratories and the small scale of models in typical civil engineering wind tunnels. To address these issues, it was proposed that a simplified flow be used in laboratory simulations, rather than a conventional ABL flow. In the simplified flow the reference mean wind speed is larger than the mean wind speed of the ABL flow, and the low-frequency fluctuations present in the ABL flow are suppressed; that is, the peak energy of the missing low-frequency fluctuations is supplied in the simplified flow by the increment in the mean wind speed, which may be regarded as a flow fluctuation with zero frequency. High-frequency turbulent fluctuations, which typically affect flow reattachment, are approximately the same in the ABL and the simplified flow. Because, over small distances, low-frequency fluctuations are highly coherent spatially for small low-rise buildings with dimensions of up to approximately 20 m (e.g., single-family residential homes), the peak aerodynamic effects of the two flows may be hypothesized to be approximately the same. Preliminary experimental results obtained in University of Western Ontario’s ABL wind tunnel facility and Florida International University’s small-scale Wall of Wind facility are shown to support this hypothesis. The use of the proposed simplified flow is currently being tested by the authors for application to computational wind engineering (CWE) applications. Such use eliminates the need to simulate the lower frequency fluctuations of the boundary layer flow and thus makes it possible to achieve practical CWE calculations, and it is advantageous in experiments from the points of view of measurement accuracy, model scaling, repeatability of the simulations, and computational efficiency. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000508