Documents disponibles écrits par cet auteur

Multicriteria capacity envelopes for biaxial bending of concrete hydraulic structures / Lucian Stefan in Journal of structural engineering, Vol. 136 N° 9 (Septembre 2010) 

Public ISBD [article]  in Journal of structural engineering > Vol. 136 N° 9 (Septembre 2010) . - pp. 1035-1043 Titre : Multicriteria capacity envelopes for biaxial bending of concrete hydraulic structures Type de document : texte imprimé Auteurs : Lucian Stefan, Auteur ; Pierre Lege, Auteur Année de publication : 2011 Article en page(s) : pp. 1035-1043 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Load  bearing  capacity  Bending  Biaxial  loads  Cracking  Hydraulic  structures  Concrete  structures  Uplift  pressure  Reinforced  concrete Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Envelopes for biaxial bending capacity of reinforced concrete elements are used extensively in design or in structural safety evaluation to verify the adequacy of internal force resultants from series of axial P and bending moments Mx and My loading pairs computed for prescribed load combinations. However, existing methods to construct P-Mx-My (PMM) interaction curves are not appropriate for concrete hydraulic structures because (1) pressurized water could penetrate in cracks leading to a coupled hydromechanical problem and (2) the structural performance is assessed using several criteria related to the allowable cracked area as well as allowable compressive (tensile) stresses for usual, unusual, and extreme load combinations. This paper presents a methodology to construct PMM interaction curves for arbitrary cross sections of hydraulic structures considering multiperformance criteria, water penetration in cracks, as well as the presence of reinforcing steel. The computations are based on a robust and efficient isogonic approach based on strength of materials where the position of the neutral axis is systematically varied over the cross section to find PMM equilibrium solutions. Four application examples of the proposed approach are presented (1) to illustrate its versatility, (2) to validate the results, and (3) to show its convergence properties. In some cases, PMM capacity envelopes are formed by distinct closed surfaces where equilibrium solutions are possible. This type of PMM capacity envelope, which the proposed algorithm is able to construct, is not found for classical reinforced concrete elements. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i9/p1035_s1?isAuthorized=no [article] Multicriteria capacity envelopes for biaxial bending of concrete hydraulic structures [texte imprimé] / Lucian Stefan, Auteur ; Pierre Lege, Auteur . - 2011 . - pp. 1035-1043. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 136 N° 9 (Septembre 2010) . - pp. 1035-1043 Mots-clés : Load  bearing  capacity  Bending  Biaxial  loads  Cracking  Hydraulic  structures  Concrete  structures  Uplift  pressure  Reinforced  concrete Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Envelopes for biaxial bending capacity of reinforced concrete elements are used extensively in design or in structural safety evaluation to verify the adequacy of internal force resultants from series of axial P and bending moments Mx and My loading pairs computed for prescribed load combinations. However, existing methods to construct P-Mx-My (PMM) interaction curves are not appropriate for concrete hydraulic structures because (1) pressurized water could penetrate in cracks leading to a coupled hydromechanical problem and (2) the structural performance is assessed using several criteria related to the allowable cracked area as well as allowable compressive (tensile) stresses for usual, unusual, and extreme load combinations. This paper presents a methodology to construct PMM interaction curves for arbitrary cross sections of hydraulic structures considering multiperformance criteria, water penetration in cracks, as well as the presence of reinforcing steel. The computations are based on a robust and efficient isogonic approach based on strength of materials where the position of the neutral axis is systematically varied over the cross section to find PMM equilibrium solutions. Four application examples of the proposed approach are presented (1) to illustrate its versatility, (2) to validate the results, and (3) to show its convergence properties. In some cases, PMM capacity envelopes are formed by distinct closed surfaces where equilibrium solutions are possible. This type of PMM capacity envelope, which the proposed algorithm is able to construct, is not found for classical reinforced concrete elements. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i9/p1035_s1?isAuthorized=no

Three-dimensional hydromechanical sectional analysis of cracked nonprismatic concrete spillway piers / Lucian Stefan in Journal of structural engineering, Vol. 138 N° 11 (Novembre 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 11 (Novembre 2012) . - pp. 1310–1320 Titre : Three-dimensional hydromechanical sectional analysis of cracked nonprismatic concrete spillway piers Type de document : texte imprimé Auteurs : Lucian Stefan, Auteur ; Pierre Léger, Auteur Année de publication : 2013 Article en page(s) : pp. 1310–1320 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Hydraulic  structures  Concrete  structures  Three-dimensional  models  Stress  analysis  Cracking  Bending  Shear  forces  Torsion Résumé : Several concrete hydraulic structures, such as spillway piers, must be considered three-dimensional (3D) components subjected to 3D loads. A very convenient approach to perform stability analysis of concrete dams is the so-called gravity method, leading to the solution of a PMM problem (axial force P and biaxial bending moments Mx, My) assuming linear normal stress distribution. If cracking takes place, water penetrates into the cracks, inducing the development of full uplift pressures (UPs). Sliding safety factors (SSFs) are computed using shear force resultants Vx, Vy, and a Mohr-Coulomb failure criterion while ignoring torsion T (VVT). This paper presents a 3D extension of the gravity method for cracked planar concrete sections of arbitrary geometry subjected to arbitrary loads (PMM-VVT). To compute the shear stress distribution, a VVT sectional analysis algorithm has been developed based on the theory of elasticity (TE), including Saint-Venant and warping torsional components combined with triangular 2D finite elements (FEs). Afterward, the SSF on the failure plane is computed from the integration of normal stresses on the remaining uncracked area where the Mohr-Coulomb criterion (considering the shear stresses from the VVT solution) has not been locally exceeded. Two validation examples and a case study of an actual pier are presented to illustrate the accuracy and efficiency of the proposed approach compared with full 3D FE analyses. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000579 [article] Three-dimensional hydromechanical sectional analysis of cracked nonprismatic concrete spillway piers [texte imprimé] / Lucian Stefan, Auteur ; Pierre Léger, Auteur . - 2013 . - pp. 1310–1320. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 11 (Novembre 2012) . - pp. 1310–1320 Mots-clés : Hydraulic  structures  Concrete  structures  Three-dimensional  models  Stress  analysis  Cracking  Bending  Shear  forces  Torsion Résumé : Several concrete hydraulic structures, such as spillway piers, must be considered three-dimensional (3D) components subjected to 3D loads. A very convenient approach to perform stability analysis of concrete dams is the so-called gravity method, leading to the solution of a PMM problem (axial force P and biaxial bending moments Mx, My) assuming linear normal stress distribution. If cracking takes place, water penetrates into the cracks, inducing the development of full uplift pressures (UPs). Sliding safety factors (SSFs) are computed using shear force resultants Vx, Vy, and a Mohr-Coulomb failure criterion while ignoring torsion T (VVT). This paper presents a 3D extension of the gravity method for cracked planar concrete sections of arbitrary geometry subjected to arbitrary loads (PMM-VVT). To compute the shear stress distribution, a VVT sectional analysis algorithm has been developed based on the theory of elasticity (TE), including Saint-Venant and warping torsional components combined with triangular 2D finite elements (FEs). Afterward, the SSF on the failure plane is computed from the integration of normal stresses on the remaining uncracked area where the Mohr-Coulomb criterion (considering the shear stresses from the VVT solution) has not been locally exceeded. Two validation examples and a case study of an actual pier are presented to illustrate the accuracy and efficiency of the proposed approach compared with full 3D FE analyses. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000579