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Ajouter le résultat dans votre panierExperimental verification of the flexibility-based damage locating vector method / Y. Gao in Journal of engineering mechanics, Vol. 133 N°10 (Octobre 2007)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1043–1049
Titre : Experimental verification of the flexibility-based damage locating vector method Type de document : texte imprimé Auteurs : Y. Gao, Auteur ; B.F Spencer, Auteur ; Dionisio Bernal, Auteur Année de publication : 2007 Article en page(s) : pp.1043–1049 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Experimentation Damage Flexibility Structural dynamics Trusse Résumé : In recent years, numerous approaches have been proposed for detecting damage in structures, in which the flexibility-based damage locating vector (DLV) method is one of the promising techniques. By computing a set of load vectors from the change of the flexibility matrix before and after damage and then applying them as static forces to the undamaged analytical model for static computation, the DLV method is able to locate damage in structures. The main purpose of this paper is to experimentally verify this method. Following a brief introduction and discussion of the motivation for the flexibility-based method, an overview of the DLV method and construction of the flexibility matrix from limited sensor information is presented. The DLV method is then experimentally verified employing a 5.6 m (18 ft)-long three-dimensional truss structure. To simulate damage in the structure, the original truss member is replaced by one with reduced stiffness. Experimental results show that the DLV method can successfully detect the damage using a limited number of sensors and modes. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1043&volume=133&issue=10&journal [...] [article] Experimental verification of the flexibility-based damage locating vector method [texte imprimé] / Y. Gao, Auteur ; B.F Spencer, Auteur ; Dionisio Bernal, Auteur . - 2007 . - pp.1043–1049.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1043–1049
Mots-clés : Experimentation Damage Flexibility Structural dynamics Trusse Résumé : In recent years, numerous approaches have been proposed for detecting damage in structures, in which the flexibility-based damage locating vector (DLV) method is one of the promising techniques. By computing a set of load vectors from the change of the flexibility matrix before and after damage and then applying them as static forces to the undamaged analytical model for static computation, the DLV method is able to locate damage in structures. The main purpose of this paper is to experimentally verify this method. Following a brief introduction and discussion of the motivation for the flexibility-based method, an overview of the DLV method and construction of the flexibility matrix from limited sensor information is presented. The DLV method is then experimentally verified employing a 5.6 m (18 ft)-long three-dimensional truss structure. To simulate damage in the structure, the original truss member is replaced by one with reduced stiffness. Experimental results show that the DLV method can successfully detect the damage using a limited number of sensors and modes. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1043&volume=133&issue=10&journal [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007)
Titre : Damping of taut-cable systems: : Two dampers on a single stay Type de document : texte imprimé Auteurs : Luca Caracoglia, Auteur ; Nicholas P. Jones, Auteur Année de publication : 2007 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Bridges cable-stayed Cables Vibration Damping Résumé : The mitigation of in-plane stay oscillation in cable-stayed bridges is commonly addressed by placing an external mechanical damper, linear or nonlinear, on each stay or by introducing transverse cross-ties among cables. Although the problem of a cable with a single external damper has found significant attention in the past and different techniques have been proposed for the solution of the free-vibration problem, limitations are related to the fact that the location of the damper is usually very close to the cable end (on the bridge deck side) due to geometric constraints, leading to inherently low modal damping in the fundamental modes. In this paper the installation of more than one damper on an individual stay is considered to overcome such limitations and to increase the overall performance of the system. An existing procedure, based on the linearized taut-string theory, was modified to allow for the presence of multiple external discrete viscous dampers. The case of two devices with arbitrary location has been solved, identifying advantages and disadvantages of the proposed solution. In addition, extensions of the practical “universal curve” and the interpretation thereof are presented. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A10%281 [...] [article] Damping of taut-cable systems: : Two dampers on a single stay [texte imprimé] / Luca Caracoglia, Auteur ; Nicholas P. Jones, Auteur . - 2007.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007)
Mots-clés : Bridges cable-stayed Cables Vibration Damping Résumé : The mitigation of in-plane stay oscillation in cable-stayed bridges is commonly addressed by placing an external mechanical damper, linear or nonlinear, on each stay or by introducing transverse cross-ties among cables. Although the problem of a cable with a single external damper has found significant attention in the past and different techniques have been proposed for the solution of the free-vibration problem, limitations are related to the fact that the location of the damper is usually very close to the cable end (on the bridge deck side) due to geometric constraints, leading to inherently low modal damping in the fundamental modes. In this paper the installation of more than one damper on an individual stay is considered to overcome such limitations and to increase the overall performance of the system. An existing procedure, based on the linearized taut-string theory, was modified to allow for the presence of multiple external discrete viscous dampers. The case of two devices with arbitrary location has been solved, identifying advantages and disadvantages of the proposed solution. In addition, extensions of the practical “universal curve” and the interpretation thereof are presented. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A10%281 [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1061–1071.
Titre : Uncoupling of potential energy in nonlinear seismic analysis of framed structures Type de document : texte imprimé Auteurs : Wong, Kevin K. F., Auteur ; Dianfeng Zhao, Auteur Année de publication : 2007 Article en page(s) : pp.1061–1071. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Energy dissipation Inelasticity Framed structures Seismic analysis Résumé : A computational analysis method is presented to investigate the potential energy of fully nonlinear framed structures and other energy characteristics due to earthquake ground motions. The overall potential energy is directly related to the stiffness of the structure, and it consists of three components in a fully nonlinear system: (1) strain energy representing the storing energy that is associated with the linear elastic portion of the structural response; (2) higher-order energy representing the energy associated with the geometric nonlinear effect of the overall structural response, which is derived from finite element method; and (3) plastic energy representing the energy dissipated by material inelasticity of the structure, and it is being derived analytically. The merit of proposed analysis method lies in the uncoupling of geometric nonlinearity and material inelasticity effects before solving for the equation of motion, and this leads directly to the analytical representations of each energy form. Both plastic energy and higher-order energy based on single-degree-of-freedom system are studied in detail to demonstrate the beauty of the proposed analysis method. In addition, a method of generating energy density spectra is also proposed, which is useful to enhance the understanding energy characteristics in seismic analysis. Finally, a five-story frame is used as a numerical example to illustrate the effectiveness and robustness of the proposed method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1061&volume=133&issue=10&journal [...] [article] Uncoupling of potential energy in nonlinear seismic analysis of framed structures [texte imprimé] / Wong, Kevin K. F., Auteur ; Dianfeng Zhao, Auteur . - 2007 . - pp.1061–1071.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1061–1071.
Mots-clés : Energy dissipation Inelasticity Framed structures Seismic analysis Résumé : A computational analysis method is presented to investigate the potential energy of fully nonlinear framed structures and other energy characteristics due to earthquake ground motions. The overall potential energy is directly related to the stiffness of the structure, and it consists of three components in a fully nonlinear system: (1) strain energy representing the storing energy that is associated with the linear elastic portion of the structural response; (2) higher-order energy representing the energy associated with the geometric nonlinear effect of the overall structural response, which is derived from finite element method; and (3) plastic energy representing the energy dissipated by material inelasticity of the structure, and it is being derived analytically. The merit of proposed analysis method lies in the uncoupling of geometric nonlinearity and material inelasticity effects before solving for the equation of motion, and this leads directly to the analytical representations of each energy form. Both plastic energy and higher-order energy based on single-degree-of-freedom system are studied in detail to demonstrate the beauty of the proposed analysis method. In addition, a method of generating energy density spectra is also proposed, which is useful to enhance the understanding energy characteristics in seismic analysis. Finally, a five-story frame is used as a numerical example to illustrate the effectiveness and robustness of the proposed method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1061&volume=133&issue=10&journal [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1072–1080.
Titre : Reliability analysis of single-degree-of-freedom elastoplastic systems. I : Critical excitations Type de document : texte imprimé Auteurs : Siu-Kui Au, Auteur ; Heung Fai Lam, Auteur ; Ching Tai Ng, Auteur Année de publication : 2007 Article en page(s) : pp. 1072–1080. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Critical load Elastoplasticity Monte Carlo method Structural reliability Vibration Noise Excitation Résumé : This paper investigates the application of importance sampling method to estimating the first passage probability of single-degree-of-freedom elastoplastic systems subjected to white noise excitations. The importance sampling density is constructed using a conventional choice as a weighted sum of Gaussian distributions centered among design points. It is well known that the design points, or equivalently the critical excitations in the function space, are difficult to obtain for nonlinear hysteretic systems. An efficient method has been developed recently for finding the critical excitations, on which this paper is based. Characteristics of the critical excitation for elastoplastic systems are explored and the efficiency of the resulting importance sampling strategy is critically assessed. It is found that some efficiency is gained by importance sampling over direct Monte Carlo method but to a lesser extent compared to its linear-elastic counterparts. The cause of this drop in efficiency will be investigated. The study calls for revisiting a basic assumption of importance sampling densities constructed using design points, where they are expected to generate samples lying frequently in the failure region, but in reality their capability should not be taken for granted. A companion paper investigates the approximation of the critical excitation that allows its simple determination. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A10%281 [...] [article] Reliability analysis of single-degree-of-freedom elastoplastic systems. I : Critical excitations [texte imprimé] / Siu-Kui Au, Auteur ; Heung Fai Lam, Auteur ; Ching Tai Ng, Auteur . - 2007 . - pp. 1072–1080.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1072–1080.
Mots-clés : Critical load Elastoplasticity Monte Carlo method Structural reliability Vibration Noise Excitation Résumé : This paper investigates the application of importance sampling method to estimating the first passage probability of single-degree-of-freedom elastoplastic systems subjected to white noise excitations. The importance sampling density is constructed using a conventional choice as a weighted sum of Gaussian distributions centered among design points. It is well known that the design points, or equivalently the critical excitations in the function space, are difficult to obtain for nonlinear hysteretic systems. An efficient method has been developed recently for finding the critical excitations, on which this paper is based. Characteristics of the critical excitation for elastoplastic systems are explored and the efficiency of the resulting importance sampling strategy is critically assessed. It is found that some efficiency is gained by importance sampling over direct Monte Carlo method but to a lesser extent compared to its linear-elastic counterparts. The cause of this drop in efficiency will be investigated. The study calls for revisiting a basic assumption of importance sampling densities constructed using design points, where they are expected to generate samples lying frequently in the failure region, but in reality their capability should not be taken for granted. A companion paper investigates the approximation of the critical excitation that allows its simple determination. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A10%281 [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1086-1092
Titre : Ocean Currents-Induced Pipeline Lateral Stability on Sandy Seabed Type de document : texte imprimé Auteurs : Fu-Ping Gao, Auteur ; Shuming Yan, Auteur ; Bing Yang, Auteur Année de publication : 2007 Article en page(s) : pp. 1086-1092 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Hydrodynamics Ocean waves Sea floor Stability Underwater pipelines Résumé : Unlike previous mechanical actuator loading methods, in this study, a hydrodynamic loading method was employed in a flow flume for simulating ocean currents induced submarine pipeline stability on a sandy seabed. It has been observed that, in the process of pipeline losing lateral stability in currents, there usually exist three characteristic times: (1) onset of sand scour; (2) slight lateral displacement of pipeline; and (3) breakout of pipeline. An empirical linear relationship is established between the dimensionless submerged weight of pipeline and Froude number for describing pipeline lateral stability in currents, in which the current-pipe-soil coupling effects are reflected. Scale effects are examined with the method of “modeling of models,” and the sand particle size effects on pipeline stability are also discussed. Moreover, the pipeline stability in currents is compared with that in waves, which indicates that the pipeline laid directly upon the sandy seabed is more laterally stable in currents than in waves. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160815 [article] Ocean Currents-Induced Pipeline Lateral Stability on Sandy Seabed [texte imprimé] / Fu-Ping Gao, Auteur ; Shuming Yan, Auteur ; Bing Yang, Auteur . - 2007 . - pp. 1086-1092.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1086-1092
Mots-clés : Hydrodynamics Ocean waves Sea floor Stability Underwater pipelines Résumé : Unlike previous mechanical actuator loading methods, in this study, a hydrodynamic loading method was employed in a flow flume for simulating ocean currents induced submarine pipeline stability on a sandy seabed. It has been observed that, in the process of pipeline losing lateral stability in currents, there usually exist three characteristic times: (1) onset of sand scour; (2) slight lateral displacement of pipeline; and (3) breakout of pipeline. An empirical linear relationship is established between the dimensionless submerged weight of pipeline and Froude number for describing pipeline lateral stability in currents, in which the current-pipe-soil coupling effects are reflected. Scale effects are examined with the method of “modeling of models,” and the sand particle size effects on pipeline stability are also discussed. Moreover, the pipeline stability in currents is compared with that in waves, which indicates that the pipeline laid directly upon the sandy seabed is more laterally stable in currents than in waves. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160815
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1093–1100.
Titre : Hysteresis in shallow water sloshing Type de document : texte imprimé Auteurs : S. M. Gardarsson, Auteur ; H. Yeh, Auteur Année de publication : 2007 Article en page(s) : pp.1093–1100. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Hysteresis Shallow water Water tanks Slopes Résumé : Hysteresis in sloshing of shallow water in horizontally excited tanks is explored experimentally. In particular the wave response to relatively large shaking amplitude near the resonant frequency is investigated for two tank configurations: a tank with horizontal bottom and vertical walls, and a tank with horizontal bottom and sloping beaches. The hysteresis behavior is clearly observed within a narrow frequency range around the shifted resonant frequency. The wave response is either in the form of smooth nonbroken waves or in the form of violent breaking waves for exactly the same set of parameters depending only on how the target oscillation frequency is tuned: i.e., whether the forcing frequency of the prior state is higher or lower than the target frequency. The consequence is that it is not possible to define a unique value for the jump frequency as it depends on the direction of the frequency tuning. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1093&volume=133&issue=10&journal [...] [article] Hysteresis in shallow water sloshing [texte imprimé] / S. M. Gardarsson, Auteur ; H. Yeh, Auteur . - 2007 . - pp.1093–1100.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1093–1100.
Mots-clés : Hysteresis Shallow water Water tanks Slopes Résumé : Hysteresis in sloshing of shallow water in horizontally excited tanks is explored experimentally. In particular the wave response to relatively large shaking amplitude near the resonant frequency is investigated for two tank configurations: a tank with horizontal bottom and vertical walls, and a tank with horizontal bottom and sloping beaches. The hysteresis behavior is clearly observed within a narrow frequency range around the shifted resonant frequency. The wave response is either in the form of smooth nonbroken waves or in the form of violent breaking waves for exactly the same set of parameters depending only on how the target oscillation frequency is tuned: i.e., whether the forcing frequency of the prior state is higher or lower than the target frequency. The consequence is that it is not possible to define a unique value for the jump frequency as it depends on the direction of the frequency tuning. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1093&volume=133&issue=10&journal [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1101–1114.
Titre : Simple model of frequency-dependent impedance functions in soil-structure interaction using frequency-independent elements Type de document : texte imprimé Auteurs : Masato Saitoh, Auteur Année de publication : 2007 Article en page(s) : pp.1101–1114. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Soil-structure interaction Elastic foundations Soil-pile interaction Dynamic analysis Embedded foundations Frequency Résumé : This study presents a methodology to make a simple equivalent model of frequency-dependent impedance functions of soil-structure interactions using a frequency-independent spring and dashpot, together with a proposed element called “gyromass.” The gyromass is frequency independent and is defined as a unit system that generates a reaction force due to the relative acceleration of the nodes between which the gyromass is placed. It is found that a model consisting of a spring, dashpot, and gyromass may generate various types of frequency-dependent impedance characteristics. This study proposes two types of simple models that express typical frequency-independent impedance functions of soil-structure interactions by using the gyromass. The advantage of these models is that the frequency-dependent characteristics can easily be expressed by a small number of elements and degrees of freedom. Moreover, they can be applied directly to conventional time-history analyses, even beyond the elastic region of the structural members. An example in which a simple model is applied to the time-history analysis of a soil-pile-superstructure system with an inelastic structural member when subjected to an earthquake wave is illustrated. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A10%281 [...] [article] Simple model of frequency-dependent impedance functions in soil-structure interaction using frequency-independent elements [texte imprimé] / Masato Saitoh, Auteur . - 2007 . - pp.1101–1114.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1101–1114.
Mots-clés : Soil-structure interaction Elastic foundations Soil-pile interaction Dynamic analysis Embedded foundations Frequency Résumé : This study presents a methodology to make a simple equivalent model of frequency-dependent impedance functions of soil-structure interactions using a frequency-independent spring and dashpot, together with a proposed element called “gyromass.” The gyromass is frequency independent and is defined as a unit system that generates a reaction force due to the relative acceleration of the nodes between which the gyromass is placed. It is found that a model consisting of a spring, dashpot, and gyromass may generate various types of frequency-dependent impedance characteristics. This study proposes two types of simple models that express typical frequency-independent impedance functions of soil-structure interactions by using the gyromass. The advantage of these models is that the frequency-dependent characteristics can easily be expressed by a small number of elements and degrees of freedom. Moreover, they can be applied directly to conventional time-history analyses, even beyond the elastic region of the structural members. An example in which a simple model is applied to the time-history analysis of a soil-pile-superstructure system with an inelastic structural member when subjected to an earthquake wave is illustrated. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A10%281 [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1115-1123
Titre : Extended transformed stress space for geomaterials and its application Type de document : texte imprimé Auteurs : Yang-Ping Yao, Auteur ; An-Nan Zhou, Auteur Année de publication : 2007 Article en page(s) : pp.1115-1123 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Geomaterials Transformations Material failure Stress Constitutive models Résumé : Because the three-dimensional strength of soil, rock, and concrete is influenced nonlinearly by the hydrostatic pressure and Lode’s angle, the failure surface is irregular in stress space, especially in the large stress range. Based on Lade’s criterion, exponential failure function in coordinate [Math Processing Error] , and the concept of original transformed stress space, an extended transformed stress space and its corresponding transformed stress tensors are proposed in this paper. Compared with original transformed stress space, the extended one would be suitable to the large stress range. Processing test results in extended transformed stress space, the unified stress-strain relationship for a certain geomaterial can be easily obtained from the test results. The validity of extended transformed stress space is confirmed by test results of soil, rock, and concrete. Based on extended transformed stress space and the Modified Cam-Clay Model, a new constitutive model is also proposed in this paper, which can be used to predict three-dimensional stress-strain relationship for soils in the large stress range. The capacity of this model is demonstrated using triaxial test results of Toyoura sand with different stress paths in the large stress range. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1115&volume=133&issue=10&journal [...] [article] Extended transformed stress space for geomaterials and its application [texte imprimé] / Yang-Ping Yao, Auteur ; An-Nan Zhou, Auteur . - 2007 . - pp.1115-1123.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1115-1123
Mots-clés : Geomaterials Transformations Material failure Stress Constitutive models Résumé : Because the three-dimensional strength of soil, rock, and concrete is influenced nonlinearly by the hydrostatic pressure and Lode’s angle, the failure surface is irregular in stress space, especially in the large stress range. Based on Lade’s criterion, exponential failure function in coordinate [Math Processing Error] , and the concept of original transformed stress space, an extended transformed stress space and its corresponding transformed stress tensors are proposed in this paper. Compared with original transformed stress space, the extended one would be suitable to the large stress range. Processing test results in extended transformed stress space, the unified stress-strain relationship for a certain geomaterial can be easily obtained from the test results. The validity of extended transformed stress space is confirmed by test results of soil, rock, and concrete. Based on extended transformed stress space and the Modified Cam-Clay Model, a new constitutive model is also proposed in this paper, which can be used to predict three-dimensional stress-strain relationship for soils in the large stress range. The capacity of this model is demonstrated using triaxial test results of Toyoura sand with different stress paths in the large stress range. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1115&volume=133&issue=10&journal [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1115-1123
Titre : Extended transformed stress space for geomaterials and its application Type de document : texte imprimé Auteurs : Yang-Ping Yao, Auteur ; An-Nan Zhou, Auteur Année de publication : 2007 Article en page(s) : pp.1115-1123 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Geomaterials Transformations Material failure Stress Constitutive models Résumé : Because the three-dimensional strength of soil, rock, and concrete is influenced nonlinearly by the hydrostatic pressure and Lode’s angle, the failure surface is irregular in stress space, especially in the large stress range. Based on Lade’s criterion, exponential failure function in coordinate [Math Processing Error] , and the concept of original transformed stress space, an extended transformed stress space and its corresponding transformed stress tensors are proposed in this paper. Compared with original transformed stress space, the extended one would be suitable to the large stress range. Processing test results in extended transformed stress space, the unified stress-strain relationship for a certain geomaterial can be easily obtained from the test results. The validity of extended transformed stress space is confirmed by test results of soil, rock, and concrete. Based on extended transformed stress space and the Modified Cam-Clay Model, a new constitutive model is also proposed in this paper, which can be used to predict three-dimensional stress-strain relationship for soils in the large stress range. The capacity of this model is demonstrated using triaxial test results of Toyoura sand with different stress paths in the large stress range. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1115&volume=133&issue=10&journal [...] [article] Extended transformed stress space for geomaterials and its application [texte imprimé] / Yang-Ping Yao, Auteur ; An-Nan Zhou, Auteur . - 2007 . - pp.1115-1123.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp.1115-1123
Mots-clés : Geomaterials Transformations Material failure Stress Constitutive models Résumé : Because the three-dimensional strength of soil, rock, and concrete is influenced nonlinearly by the hydrostatic pressure and Lode’s angle, the failure surface is irregular in stress space, especially in the large stress range. Based on Lade’s criterion, exponential failure function in coordinate [Math Processing Error] , and the concept of original transformed stress space, an extended transformed stress space and its corresponding transformed stress tensors are proposed in this paper. Compared with original transformed stress space, the extended one would be suitable to the large stress range. Processing test results in extended transformed stress space, the unified stress-strain relationship for a certain geomaterial can be easily obtained from the test results. The validity of extended transformed stress space is confirmed by test results of soil, rock, and concrete. Based on extended transformed stress space and the Modified Cam-Clay Model, a new constitutive model is also proposed in this paper, which can be used to predict three-dimensional stress-strain relationship for soils in the large stress range. The capacity of this model is demonstrated using triaxial test results of Toyoura sand with different stress paths in the large stress range. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1115&volume=133&issue=10&journal [...]
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1124-1133
Titre : Numeric-analytic form of the adomian decomposition method for two-point boundary value problems in nonlinear mechanics Type de document : texte imprimé Auteurs : S. Ghosh, Auteur ; D. Roy, Auteur Année de publication : 2007 Article en page(s) : pp. 1124-1133 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Decomposition Numerical analysis Algorithms Differential equations Résumé : A new numeric-analytic technique is developed for two-point nonlinear boundary-value problems (BVPs) of engineering interest. The analytic part of the method is based on a conventional Adomian decomposition method (ADM). However, given a discretization of the one-dimensional domain, the present algorithm applies the ADM, repetitively over successive intervals and exploits a shooting algorithm to solve the BVPs. Apart from a very high rate of convergence as the discretization is made finer, yet another significant advantage of the method is that it provides the solution in a piecewise functional form and one can finally arrive at a continuous form of the global solution. The procedure is used to study planar, large-deflection (Elastica) problem of a cantilever beam subjected to a transverse, concentrated load, at its free end. Moreover the elastoplastic behavior of a cantilever is also studied. Comparisons with exact solutions as well as with results via a few other competing algorithms demonstrate the remarkable accuracy of the proposed method. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160819 [article] Numeric-analytic form of the adomian decomposition method for two-point boundary value problems in nonlinear mechanics [texte imprimé] / S. Ghosh, Auteur ; D. Roy, Auteur . - 2007 . - pp. 1124-1133.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1124-1133
Mots-clés : Decomposition Numerical analysis Algorithms Differential equations Résumé : A new numeric-analytic technique is developed for two-point nonlinear boundary-value problems (BVPs) of engineering interest. The analytic part of the method is based on a conventional Adomian decomposition method (ADM). However, given a discretization of the one-dimensional domain, the present algorithm applies the ADM, repetitively over successive intervals and exploits a shooting algorithm to solve the BVPs. Apart from a very high rate of convergence as the discretization is made finer, yet another significant advantage of the method is that it provides the solution in a piecewise functional form and one can finally arrive at a continuous form of the global solution. The procedure is used to study planar, large-deflection (Elastica) problem of a cantilever beam subjected to a transverse, concentrated load, at its free end. Moreover the elastoplastic behavior of a cantilever is also studied. Comparisons with exact solutions as well as with results via a few other competing algorithms demonstrate the remarkable accuracy of the proposed method. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160819
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1134-1145
Titre : Elastodynamic potential method for transversely isotropic solid Type de document : texte imprimé Auteurs : Mohammad Rahimian, Auteur ; Eskandari-Ghadi, Morteza, Auteur Année de publication : 2007 Article en page(s) : pp. 1134-1145 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Wave propagation Half space Elasticity Isotropy Displacement Boundary element method Résumé : A theoretical formulation is presented for the determination of the displacements, strains, and stresses in a three-dimensional transversely isotropic linearly elastic medium. By means of a complete representation using two displacement potentials, it is shown that the governing equations of motion for this class of problems can be uncoupled into a fourth-order and a second-order partial differential equation in terms of the spatial and time coordinate under general conditions. Compatible with Fourier expansions and Hankel transforms in a cylindrical coordinate system, the formulation includes a complete set of transformed displacement-potential, strain-potential, and stress-potential relations that can be useful in a variety of elastodynamic as well as elastostatic problems. As an illustration of the application of the method, the solution for a half-space under the action of arbitrarily distributed, time-harmonic surface traction is derived, including its specialization to uniform patch loads and point forces. To confirm the accuracy of the numerical evaluation of the integrals involved, numerical results are also included for cases of different degree of the material anisotropy, frequency of excitation, and compared with existing solutions. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160820 [article] Elastodynamic potential method for transversely isotropic solid [texte imprimé] / Mohammad Rahimian, Auteur ; Eskandari-Ghadi, Morteza, Auteur . - 2007 . - pp. 1134-1145.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1134-1145
Mots-clés : Wave propagation Half space Elasticity Isotropy Displacement Boundary element method Résumé : A theoretical formulation is presented for the determination of the displacements, strains, and stresses in a three-dimensional transversely isotropic linearly elastic medium. By means of a complete representation using two displacement potentials, it is shown that the governing equations of motion for this class of problems can be uncoupled into a fourth-order and a second-order partial differential equation in terms of the spatial and time coordinate under general conditions. Compatible with Fourier expansions and Hankel transforms in a cylindrical coordinate system, the formulation includes a complete set of transformed displacement-potential, strain-potential, and stress-potential relations that can be useful in a variety of elastodynamic as well as elastostatic problems. As an illustration of the application of the method, the solution for a half-space under the action of arbitrarily distributed, time-harmonic surface traction is derived, including its specialization to uniform patch loads and point forces. To confirm the accuracy of the numerical evaluation of the integrals involved, numerical results are also included for cases of different degree of the material anisotropy, frequency of excitation, and compared with existing solutions. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160820
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1146-1150
Titre : Axisymmetric deformation of a pressurized thin elastic membrane with nonuniform thickness Type de document : texte imprimé Auteurs : Xi Chen, Auteur Année de publication : 2007 Article en page(s) : pp. 1146-1150 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Axisymmetry DeformationElasticity Membranes Pressures Thickness. Résumé : Many circular elastic membranes used in practice involve nonuniform thickness, which is a main source of error that affects the functionality of the membrane. An analytical framework is developed in this paper to solve the deflection profile of a pressurized circular membrane with nonuniform thickness. The nonlinear solution is established within the deformed configuration. The results are compared with finite-element simulation with good agreement. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160821 [article] Axisymmetric deformation of a pressurized thin elastic membrane with nonuniform thickness [texte imprimé] / Xi Chen, Auteur . - 2007 . - pp. 1146-1150.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1146-1150
Mots-clés : Axisymmetry DeformationElasticity Membranes Pressures Thickness. Résumé : Many circular elastic membranes used in practice involve nonuniform thickness, which is a main source of error that affects the functionality of the membrane. An analytical framework is developed in this paper to solve the deflection profile of a pressurized circular membrane with nonuniform thickness. The nonlinear solution is established within the deformed configuration. The results are compared with finite-element simulation with good agreement. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160821
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