Dépouillements

Axisymmetric stress analysis of a thick conical shell with varying thickness under nonuniform internal ressure / H. R. Eipakchi in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.601–610. Titre : Axisymmetric stress analysis of a thick conical shell with varying thickness under nonuniform internal ressure Type de document : texte imprimé Auteurs : H. R. Eipakchi, Auteur ; S. E. Khadem, Auteur ; G. H. Rahimi S., Auteur Année de publication : 2008 Article en page(s) : pp.601–610. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Shells  Thickness  Finite  element  method  Shear  deformation  Internal  pressure  Stress Résumé : A mathematical approach based on the perturbation theory has been used for axisymmetric stress analysis of a thick conical shell with varying thickness under nonuniform internal pressure. The equilibrium equations have been derived using the energy principle and considering the second-order shear deformation theory (SSDT), which includes shear deformation effects. This system of ordinary differential equations with variable coefficients has been solved analytically using the matched asymptotic expansion method of the perturbation theory. A comparison of the results with the finite-element method and the first-order shear deformation theory shows that the SSDT can predict the displacements and stresses of the shell for a wide range of thicknesses as well with less calculations than other analytical methods such as the Frobenius series method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2860 [...] [article] Axisymmetric stress analysis of a thick conical shell with varying thickness under nonuniform internal ressure [texte imprimé] / H. R. Eipakchi, Auteur ; S. E. Khadem, Auteur ; G. H. Rahimi S., Auteur . - 2008 . - pp.601–610. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.601–610. Mots-clés : Shells  Thickness  Finite  element  method  Shear  deformation  Internal  pressure  Stress Résumé : A mathematical approach based on the perturbation theory has been used for axisymmetric stress analysis of a thick conical shell with varying thickness under nonuniform internal pressure. The equilibrium equations have been derived using the energy principle and considering the second-order shear deformation theory (SSDT), which includes shear deformation effects. This system of ordinary differential equations with variable coefficients has been solved analytically using the matched asymptotic expansion method of the perturbation theory. A comparison of the results with the finite-element method and the first-order shear deformation theory shows that the SSDT can predict the displacements and stresses of the shell for a wide range of thicknesses as well with less calculations than other analytical methods such as the Frobenius series method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2860 [...]

On mechanical degradation of reinforced concrete affected by alkali-silica reaction / A. Winnicki in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.611–627. Titre : On mechanical degradation of reinforced concrete affected by alkali-silica reaction Type de document : texte imprimé Auteurs : A. Winnicki, Auteur ; S. Pietruszczak, Auteur Année de publication : 2008 Article en page(s) : pp.611–627. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Concrete  reinforced  Plasticity  Degradation  Mechanical  properties Résumé : In this paper a constitutive relation is developed for reinforced concrete subjected to a continuing alkali-silica reaction. The chemo-mechanical interaction is described within the framework of chemo-plasticity. The formulation invokes the assumption that the formation of expansive phases results in degradation of mechanical properties of the material. The approach employs a constitutive model for reinforced concrete, as recently developed by the writers. An extensive numerical analysis is conducted examining the effect of the reaction on mechanical characteristics in axial compression/tension for different reinforcement intensities. Some of the key results are compared with the available experimental data. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2861 [...] [article] On mechanical degradation of reinforced concrete affected by alkali-silica reaction [texte imprimé] / A. Winnicki, Auteur ; S. Pietruszczak, Auteur . - 2008 . - pp.611–627. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.611–627. Mots-clés : Concrete  reinforced  Plasticity  Degradation  Mechanical  properties Résumé : In this paper a constitutive relation is developed for reinforced concrete subjected to a continuing alkali-silica reaction. The chemo-mechanical interaction is described within the framework of chemo-plasticity. The formulation invokes the assumption that the formation of expansive phases results in degradation of mechanical properties of the material. The approach employs a constitutive model for reinforced concrete, as recently developed by the writers. An extensive numerical analysis is conducted examining the effect of the reaction on mechanical characteristics in axial compression/tension for different reinforcement intensities. Some of the key results are compared with the available experimental data. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2861 [...]

Monte carlo methods for estimating the extreme response of dynamical systems / Arvid Naess in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 628-636 Titre : Monte carlo methods for estimating the extreme response of dynamical systems Type de document : texte imprimé Auteurs : Arvid Naess, Auteur ; O. Gaidai, Auteur Année de publication : 2008 Article en page(s) : pp. 628-636 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Monte  Carlo  method  Nonlinear  systems  Estimation Résumé : The development of simple accurate, and efficient methods for estimation of the extreme response of dynamical systems subjected to random excitations is discussed in the present paper. The key quantity for calculating the statistical distribution of extreme response is the mean level upcrossing rate function. By exploiting the regularity of the tail behavior of this function, an efficient simulation based methodology for estimating the extreme response distribution function is developed. This makes it possible to avoid the commonly adopted assumption that the extreme value data follow an appropriate asymptotic extreme value distribution, which would be a Gumbel distribution for the models considered in this paper. It is demonstrated that the commonly quoted obstacle against using the standard Monte Carlo method for estimating extreme responses, i.e., excessive CPU time, can be circumvented, bringing the computational efforts down to quite acceptable levels. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166077 [article] Monte carlo methods for estimating the extreme response of dynamical systems [texte imprimé] / Arvid Naess, Auteur ; O. Gaidai, Auteur . - 2008 . - pp. 628-636. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 628-636 Mots-clés : Monte  Carlo  method  Nonlinear  systems  Estimation Résumé : The development of simple accurate, and efficient methods for estimation of the extreme response of dynamical systems subjected to random excitations is discussed in the present paper. The key quantity for calculating the statistical distribution of extreme response is the mean level upcrossing rate function. By exploiting the regularity of the tail behavior of this function, an efficient simulation based methodology for estimating the extreme response distribution function is developed. This makes it possible to avoid the commonly adopted assumption that the extreme value data follow an appropriate asymptotic extreme value distribution, which would be a Gumbel distribution for the models considered in this paper. It is demonstrated that the commonly quoted obstacle against using the standard Monte Carlo method for estimating extreme responses, i.e., excessive CPU time, can be circumvented, bringing the computational efforts down to quite acceptable levels. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166077

Seismic protection of a building complex using variable friction damper / Y. L. Xu in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 637-649 Titre : Seismic protection of a building complex using variable friction damper : Experimental investigation Type de document : texte imprimé Auteurs : Y. L. Xu, Auteur ; C. L. Ng, Auteur Année de publication : 2008 Article en page(s) : pp. 637-649 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Structural  control  Damping  Algorithms  Shake  table  tests  Piezoelectricity  Seismic  effects  Experimentation Résumé : This study presents an experimental investigation of seismic control of a building complex using variable friction damper. The laboratory-scale building complex was composed of a 12-story building and a three-story podium structure coupled in different configurations. The laboratory-scale variable friction damper was tailor made with a piezoelectric actuator. The performance test of the piezoelectric actuator was carried out to identify its characteristics. The performance test was then conducted on the piezo-driven variable friction damper under either constant or varying voltage to identify its motion-independent characteristics. Based on the characterization results, a close-loop operating scheme was proposed together with two classes of semiactive controllers: local-feedback controller and global-feedback controller, for real-time manipulation of the damper. The building complex was finally tested in uncoupled, rigid-coupled, passive damper-coupled, and semiactive damper-coupled configurations. The control performance of variable friction damper for the building complex was examined and compared with other cases. The test results showed that semiactive coupling control was promising for reducing seismic responses of both buildings. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166078 [article] Seismic protection of a building complex using variable friction damper : Experimental investigation [texte imprimé] / Y. L. Xu, Auteur ; C. L. Ng, Auteur . - 2008 . - pp. 637-649. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 637-649 Mots-clés : Structural  control  Damping  Algorithms  Shake  table  tests  Piezoelectricity  Seismic  effects  Experimentation Résumé : This study presents an experimental investigation of seismic control of a building complex using variable friction damper. The laboratory-scale building complex was composed of a 12-story building and a three-story podium structure coupled in different configurations. The laboratory-scale variable friction damper was tailor made with a piezoelectric actuator. The performance test of the piezoelectric actuator was carried out to identify its characteristics. The performance test was then conducted on the piezo-driven variable friction damper under either constant or varying voltage to identify its motion-independent characteristics. Based on the characterization results, a close-loop operating scheme was proposed together with two classes of semiactive controllers: local-feedback controller and global-feedback controller, for real-time manipulation of the damper. The building complex was finally tested in uncoupled, rigid-coupled, passive damper-coupled, and semiactive damper-coupled configurations. The control performance of variable friction damper for the building complex was examined and compared with other cases. The test results showed that semiactive coupling control was promising for reducing seismic responses of both buildings. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166078

Ambient vibration data analysis for structural identification and global condition assessment / Mustafa Gul in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 650-662 Titre : Ambient vibration data analysis for structural identification and global condition assessment Type de document : texte imprimé Auteurs : Mustafa Gul, Auteur ; F. Necati Catbas, Auteur Année de publication : 2008 Article en page(s) : pp. 650-662 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Structural  dynamics  Vibration  Impact  tests  Modal  analysis  Flexibility  Damage. Résumé : System identification is an area which deals with developing mathematical models to characterize the input-output behavior of an unknown system by means of experimental data. Structural health monitoring (SHM) provides the tools and technologies to collect and analyze input and output data to track the structural behavior. One of the most commonly used SHM technologies is dynamic testing. Ambient vibration testing is a practical dynamic testing method especially for large civil structures where input excitation cannot be directly measured. This paper presents a conceptual and reliable methodology for system identification and structural condition assessment using ambient vibration data where input data are not available. The system identification methodology presented in this study is based on the use of complex mode indicator functions (CMIFs) coupled with the random decrement (RD) method to identify the modal parameters from the output only data sets. CMIF is employed for parameter identification from the unscaled multiple-input multiple-output data sets generated using the RD method. For condition assessment, unscaled flexibility and the deflection profiles obtained from the dynamic tests are presented as a conceptual indicator. Laboratory tests on a steel grid and field tests on a long-span bridge were conducted and the dynamic properties identified from these tests are presented. For demonstrating condition assessment, deflected shapes obtained from unscaled flexibility are compared for undamaged and damaged laboratory grid structures. It is shown that structural changes on the steel grid structure are identified by using the unscaled deflected shapes. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166079 [article] Ambient vibration data analysis for structural identification and global condition assessment [texte imprimé] / Mustafa Gul, Auteur ; F. Necati Catbas, Auteur . - 2008 . - pp. 650-662. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 650-662 Mots-clés : Structural  dynamics  Vibration  Impact  tests  Modal  analysis  Flexibility  Damage. Résumé : System identification is an area which deals with developing mathematical models to characterize the input-output behavior of an unknown system by means of experimental data. Structural health monitoring (SHM) provides the tools and technologies to collect and analyze input and output data to track the structural behavior. One of the most commonly used SHM technologies is dynamic testing. Ambient vibration testing is a practical dynamic testing method especially for large civil structures where input excitation cannot be directly measured. This paper presents a conceptual and reliable methodology for system identification and structural condition assessment using ambient vibration data where input data are not available. The system identification methodology presented in this study is based on the use of complex mode indicator functions (CMIFs) coupled with the random decrement (RD) method to identify the modal parameters from the output only data sets. CMIF is employed for parameter identification from the unscaled multiple-input multiple-output data sets generated using the RD method. For condition assessment, unscaled flexibility and the deflection profiles obtained from the dynamic tests are presented as a conceptual indicator. Laboratory tests on a steel grid and field tests on a long-span bridge were conducted and the dynamic properties identified from these tests are presented. For demonstrating condition assessment, deflected shapes obtained from unscaled flexibility are compared for undamaged and damaged laboratory grid structures. It is shown that structural changes on the steel grid structure are identified by using the unscaled deflected shapes. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166079

Human jumping and bobbing forces on flexible structures / R. E. Harrison in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.663–675. Titre : Human jumping and bobbing forces on flexible structures : Effect of structural properties Type de document : texte imprimé Auteurs : R. E. Harrison, Auteur ; S. Yao, Auteur ; J. R. Wright, Auteur Année de publication : 2008 Article en page(s) : pp.663–675. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Dynamic  loads  Biomechanics  Serviceability  Structural  dynamics  Vibration  Laboratory  tests Résumé : The behavior of humans jumping and bobbing on flexible structures has become a matter of some concern for both structural integrity and human tolerance. The issue is of great importance for a number of structure types including stadia terraces. A unique test rig has been developed for exploring the forces, accelerations, and displacements that occur when a human subject jumps or bobs on a flexible structure where motion can be perceived. In tests reported earlier, it was found that the subject is able to generate near resonant structural response but it is extremely difficult, if not impossible, to jump or bob at or very near to the natural frequency of the structure when its vertical motion is significant. Also, under such near-resonant conditions, the force developed by the subject was found to drop significantly. In this paper, the effect of altering the subject-to-structure mass ratio and the damping ratio of the structure on these phenomena is presented. As would be expected, it is shown that as the structure becomes more massive and more highly damped it moves less for nominally the same excitation. In this situation, it becomes easier to jump and bob near to resonance and the degree of force dropout reduces, although it is still significant for even the most massive and highly damped case considered. A method for including these effects of human-structure interaction in a load model for dynamic response calculations is then proposed. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2866 [...] [article] Human jumping and bobbing forces on flexible structures : Effect of structural properties [texte imprimé] / R. E. Harrison, Auteur ; S. Yao, Auteur ; J. R. Wright, Auteur . - 2008 . - pp.663–675. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.663–675. Mots-clés : Dynamic  loads  Biomechanics  Serviceability  Structural  dynamics  Vibration  Laboratory  tests Résumé : The behavior of humans jumping and bobbing on flexible structures has become a matter of some concern for both structural integrity and human tolerance. The issue is of great importance for a number of structure types including stadia terraces. A unique test rig has been developed for exploring the forces, accelerations, and displacements that occur when a human subject jumps or bobs on a flexible structure where motion can be perceived. In tests reported earlier, it was found that the subject is able to generate near resonant structural response but it is extremely difficult, if not impossible, to jump or bob at or very near to the natural frequency of the structure when its vertical motion is significant. Also, under such near-resonant conditions, the force developed by the subject was found to drop significantly. In this paper, the effect of altering the subject-to-structure mass ratio and the damping ratio of the structure on these phenomena is presented. As would be expected, it is shown that as the structure becomes more massive and more highly damped it moves less for nominally the same excitation. In this situation, it becomes easier to jump and bob near to resonance and the degree of force dropout reduces, although it is still significant for even the most massive and highly damped case considered. A method for including these effects of human-structure interaction in a load model for dynamic response calculations is then proposed. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2866 [...]

Development of direct integration algorithms for structural dynamics using discrete control theory / Cheng Chen in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 676–683. Titre : Development of direct integration algorithms for structural dynamics using discrete control theory Type de document : texte imprimé Auteurs : Cheng Chen, Auteur ; Ricles, James M., Auteur Année de publication : 2008 Article en page(s) : pp. 676–683. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Algorithms  Structural  dynamics  Transfer  functions  Stability  Discrete  elements Résumé : In structural dynamics, integration algorithms are often used to obtain the solution of temporally discretized equations of motion at selected time steps. Various time integration algorithms have been developed in the time domain using different methods. In order for an integration algorithm to be reliable it must be stable and accurate. A discrete transfer function is used to study the properties of integration algorithms. A pole mapping rule from control theory in conjunction with a discrete transfer function is used to develop new integration algorithms for obtaining solutions to structural dynamics problems. A new explicit integration algorithm, called the CR (Chen and Ricles) algorithm, is subsequently developed based on the proposed method. The properties of the algorithm are investigated and compared with other well established algorithms such as the Newmark family of integration algorithms. By assigning proper stable poles to the discrete transfer function the newly developed CR explicit algorithm is unconditionally stable and has the same accuracy as the Newmark method with constant acceleration. In addition, the CR algorithm is based on expressions for displacement and velocity that are both explicit in form, making it an appealing integration algorithm for solving structural dynamics problems. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2867 [...] [article] Development of direct integration algorithms for structural dynamics using discrete control theory [texte imprimé] / Cheng Chen, Auteur ; Ricles, James M., Auteur . - 2008 . - pp. 676–683. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 676–683. Mots-clés : Algorithms  Structural  dynamics  Transfer  functions  Stability  Discrete  elements Résumé : In structural dynamics, integration algorithms are often used to obtain the solution of temporally discretized equations of motion at selected time steps. Various time integration algorithms have been developed in the time domain using different methods. In order for an integration algorithm to be reliable it must be stable and accurate. A discrete transfer function is used to study the properties of integration algorithms. A pole mapping rule from control theory in conjunction with a discrete transfer function is used to develop new integration algorithms for obtaining solutions to structural dynamics problems. A new explicit integration algorithm, called the CR (Chen and Ricles) algorithm, is subsequently developed based on the proposed method. The properties of the algorithm are investigated and compared with other well established algorithms such as the Newmark family of integration algorithms. By assigning proper stable poles to the discrete transfer function the newly developed CR explicit algorithm is unconditionally stable and has the same accuracy as the Newmark method with constant acceleration. In addition, the CR algorithm is based on expressions for displacement and velocity that are both explicit in form, making it an appealing integration algorithm for solving structural dynamics problems. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2867 [...]

Capturing nonlinear vibratory roller compactor behavior through lumped parameter modeling / Paul J. van Susante in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.684–693. Titre : Capturing nonlinear vibratory roller compactor behavior through lumped parameter modeling Type de document : texte imprimé Auteurs : Paul J. van Susante, Auteur ; Michael A. Mooney, Auteur Année de publication : 2008 Article en page(s) : pp.684–693. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Data  analysis  Geotechnical  models  Dynamic  models  Nonlinear  systems  Soil  compaction  Soil  dynamics  Parameters Résumé : Continuous monitoring of soil properties using an instrumented roller compactor requires models that can capture the essential features observed during drum/soil vibration. This paper presents the results of lumped parameter modeling of the drum/soil system together with data from complex nonlinear behavior observed experimentally during operation on sandy soil. Model parameters and response were developed using experimental data collected over a wide range of operating frequencies. Three and four-degree-of-freedom (DOF) models with linear and nonlinear soil elements were investigated. The results showed that a 3DOF model incorporating the soil, drum, and frame of the roller was successful in capturing behavior during coupled drum/soil vibration and during decoupling (i.e., loss of contact between drum and soil). Modeling the drum/soil decoupling accounted for most of the experimentally observed nonlinearity. The addition of nonlinear soil stiffness due to the curved drum effect and due to strain hardening soil behavior accounted for additional nonlinearity observed experimentally. Experimentally observed drum rocking during coupled drum/soil vibration was successfully modeled with a 4DOF drum-frame model. The analysis also revealed that commonly observed heterogeneous soil conditions give rise to a transient response that can have a significant influence on vibration behavior. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2868 [...] [article] Capturing nonlinear vibratory roller compactor behavior through lumped parameter modeling [texte imprimé] / Paul J. van Susante, Auteur ; Michael A. Mooney, Auteur . - 2008 . - pp.684–693. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp.684–693. Mots-clés : Data  analysis  Geotechnical  models  Dynamic  models  Nonlinear  systems  Soil  compaction  Soil  dynamics  Parameters Résumé : Continuous monitoring of soil properties using an instrumented roller compactor requires models that can capture the essential features observed during drum/soil vibration. This paper presents the results of lumped parameter modeling of the drum/soil system together with data from complex nonlinear behavior observed experimentally during operation on sandy soil. Model parameters and response were developed using experimental data collected over a wide range of operating frequencies. Three and four-degree-of-freedom (DOF) models with linear and nonlinear soil elements were investigated. The results showed that a 3DOF model incorporating the soil, drum, and frame of the roller was successful in capturing behavior during coupled drum/soil vibration and during decoupling (i.e., loss of contact between drum and soil). Modeling the drum/soil decoupling accounted for most of the experimentally observed nonlinearity. The addition of nonlinear soil stiffness due to the curved drum effect and due to strain hardening soil behavior accounted for additional nonlinearity observed experimentally. Experimentally observed drum rocking during coupled drum/soil vibration was successfully modeled with a 4DOF drum-frame model. The analysis also revealed that commonly observed heterogeneous soil conditions give rise to a transient response that can have a significant influence on vibration behavior. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2868 [...]

Two-dimensional nonlinear analysis of long cables / C. V. Girija Vallabhan in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 694–697. Titre : Two-dimensional nonlinear analysis of long cables Type de document : texte imprimé Auteurs : C. V. Girija Vallabhan, Auteur Année de publication : 2008 Article en page(s) : pp. 694–697. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Nonlinear  analysis  Cables  Finite  difference  method  Concentrated  loads Résumé : A simple finite-difference iterative model is presented here for the nonlinear analysis of a long inclined cable due to its self-weight and other concentrated loads in between. The input requires the end coordinates, area of cross section, modulus of elasticity, and initial tension of the cable. If the ends of the cable are subjected to displacements, the tension in the cable varies nonlinearly and the new deformed shape is computed using an iterative procedure. Unlike finite-element methods, initial cable geometry is not required here, and the method automatically computes the initial geometry even with concentrated loads. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2869 [...] [article] Two-dimensional nonlinear analysis of long cables [texte imprimé] / C. V. Girija Vallabhan, Auteur . - 2008 . - pp. 694–697. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 694–697. Mots-clés : Nonlinear  analysis  Cables  Finite  difference  method  Concentrated  loads Résumé : A simple finite-difference iterative model is presented here for the nonlinear analysis of a long inclined cable due to its self-weight and other concentrated loads in between. The input requires the end coordinates, area of cross section, modulus of elasticity, and initial tension of the cable. If the ends of the cable are subjected to displacements, the tension in the cable varies nonlinearly and the new deformed shape is computed using an iterative procedure. Unlike finite-element methods, initial cable geometry is not required here, and the method automatically computes the initial geometry even with concentrated loads. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2869 [...]

Stochastic response and stability of a nonintegrable system / Deepak Kumar in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 698-702 Titre : Stochastic response and stability of a nonintegrable system Type de document : texte imprimé Auteurs : Deepak Kumar, Auteur ; T. K. Datta, Auteur Année de publication : 2008 Article en page(s) : pp. 698-702 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Markov  process  Nonlinear  systems  Stability  Stochastic  processes Résumé : For determining the stochastic response and stability of a strongly nonlinear single-degree-of-freedom system using the stochastic averaging technique, the size of excitations should be small such that the response of the system converges weakly to a Markov process. This condition is not often met with practical problems, and therefore, application of this method for obtaining their responses becomes difficult. Further, for systems with nonlinearities that cannot be integrated in closed form, stability analysis by examining the conditions of the two boundaries of the problem is not possible. A semianalytical method along with a weighted residual technique is presented here to circumvent these difficulties and to determine the response and stability of a strongly nonlinear system subjected to sizable stochastic excitation. The weighted residual technique is employed to correct the errors in averaged drift and diffusion coefficients resulting due to the size of the stochastic excitation. Two example problems are solved as illustrations of the method ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166084 [article] Stochastic response and stability of a nonintegrable system [texte imprimé] / Deepak Kumar, Auteur ; T. K. Datta, Auteur . - 2008 . - pp. 698-702. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 698-702 Mots-clés : Markov  process  Nonlinear  systems  Stability  Stochastic  processes Résumé : For determining the stochastic response and stability of a strongly nonlinear single-degree-of-freedom system using the stochastic averaging technique, the size of excitations should be small such that the response of the system converges weakly to a Markov process. This condition is not often met with practical problems, and therefore, application of this method for obtaining their responses becomes difficult. Further, for systems with nonlinearities that cannot be integrated in closed form, stability analysis by examining the conditions of the two boundaries of the problem is not possible. A semianalytical method along with a weighted residual technique is presented here to circumvent these difficulties and to determine the response and stability of a strongly nonlinear system subjected to sizable stochastic excitation. The weighted residual technique is employed to correct the errors in averaged drift and diffusion coefficients resulting due to the size of the stochastic excitation. Two example problems are solved as illustrations of the method ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?166084

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