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Ajouter le résultat dans votre panierOptimal design strategy of connected control method for two dynamically similar structures / K. Makita in Journal of engineering mechanics, Vol. 133 N°11 (Novembre 2007)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1247–1257.
Titre : Optimal design strategy of connected control method for two dynamically similar structures Type de document : texte imprimé Auteurs : K. Makita, Auteur ; R. E. Christenson, Auteur ; K. Seto, Auteur Année de publication : 2007 Article en page(s) : pp.1247–1257. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Structural control Seismic analysis Passive control Optimization Design Résumé : Structural control of adjacent flexible structures has been shown to be effectively accomplished using the connected control method (CCM), which uses an auxiliary structure to provide a reaction force. A perceived constraint of the CCM is the ineffective control of structures with similar dynamics. However, the writers have presented a modified CCM mechanism in which dampers are connected between dynamically similar structures with a difference in connection height using cantilever structures. The research described in this paper extends the CCM to couple two dynamically similar structures and determines optimal stiffness and damping in the connector link. A two-degree-of-freedom building model is developed for the optimal design of the connected control devices. The optimal solutions of the connector stiffness and damping take into account the presence of fixed points in the systems transfer functions. Analytical results confirm the effectiveness of the proposed method and design. Experimental tests then verify the response reduction capabilities of the proposed optimal design. ISSN : 0733-9399 En ligne : Structural control, Seismic analysis, Passive control, Optimization, Design Read [...] [article] Optimal design strategy of connected control method for two dynamically similar structures [texte imprimé] / K. Makita, Auteur ; R. E. Christenson, Auteur ; K. Seto, Auteur . - 2007 . - pp.1247–1257.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1247–1257.
Mots-clés : Structural control Seismic analysis Passive control Optimization Design Résumé : Structural control of adjacent flexible structures has been shown to be effectively accomplished using the connected control method (CCM), which uses an auxiliary structure to provide a reaction force. A perceived constraint of the CCM is the ineffective control of structures with similar dynamics. However, the writers have presented a modified CCM mechanism in which dampers are connected between dynamically similar structures with a difference in connection height using cantilever structures. The research described in this paper extends the CCM to couple two dynamically similar structures and determines optimal stiffness and damping in the connector link. A two-degree-of-freedom building model is developed for the optimal design of the connected control devices. The optimal solutions of the connector stiffness and damping take into account the presence of fixed points in the systems transfer functions. Analytical results confirm the effectiveness of the proposed method and design. Experimental tests then verify the response reduction capabilities of the proposed optimal design. ISSN : 0733-9399 En ligne : Structural control, Seismic analysis, Passive control, Optimization, Design Read [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1258–1267.
Titre : Markov chain monte carlo-based method for flaw detection in beams Type de document : texte imprimé Auteurs : Roland E. Glasser, Auteur ; Christopher L. Lee, Auteur ; John J. Nitao, Auteur Année de publication : 2007 Article en page(s) : pp. 1258–1267. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Markov chains Monte Carlo method Bayesian analysis Structural models Damage Cantilevers Résumé : A Bayesian inference methodology using a Markov chain Monte Carlo (MCMC) sampling procedure is presented for estimating the parameters of computational structural models. This methodology combines prior information, measured data, and forward models to produce a posterior distribution for the system parameters of structural models that is most consistent with all available data. The MCMC procedure is based upon a Metropolis-Hastings algorithm that is shown to function effectively with noisy data, incomplete data sets, and mismatched computational nodes/measurement points. A series of numerical test cases based upon a cantilever beam is presented. The results demonstrate that the algorithm is able to estimate model parameters utilizing experimental data for the nodal displacements resulting from specified forces. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Markov chain monte carlo-based method for flaw detection in beams [texte imprimé] / Roland E. Glasser, Auteur ; Christopher L. Lee, Auteur ; John J. Nitao, Auteur . - 2007 . - pp. 1258–1267.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1258–1267.
Mots-clés : Markov chains Monte Carlo method Bayesian analysis Structural models Damage Cantilevers Résumé : A Bayesian inference methodology using a Markov chain Monte Carlo (MCMC) sampling procedure is presented for estimating the parameters of computational structural models. This methodology combines prior information, measured data, and forward models to produce a posterior distribution for the system parameters of structural models that is most consistent with all available data. The MCMC procedure is based upon a Metropolis-Hastings algorithm that is shown to function effectively with noisy data, incomplete data sets, and mismatched computational nodes/measurement points. A series of numerical test cases based upon a cantilever beam is presented. The results demonstrate that the algorithm is able to estimate model parameters utilizing experimental data for the nodal displacements resulting from specified forces. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1268–1277.
Titre : Free-edge and ply cracking effect in angle-ply laminated cloads omposites subjected to in-plane Type de document : texte imprimé Auteurs : Daxu Zhang, Auteur ; Jianqiao Ye, Auteur ; Dennis Lam, Auteur Année de publication : 2007 Article en page(s) : pp. 1268–1277. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Anisotropy Materials Laminates Edge effect Cracking Interfaces Stress analysis Résumé : This paper presents a semianalytical method for the prediction of interlaminar stresses and displacements near the free edges and ply cracks in general angle-ply laminates subjected to biaxial extensions and/or in plane shear deformation. The method is based on a state space representation of the three-dimensional equations of elasticity. Numerical solutions are obtained by using layer refinement in the through thickness direction and Fourier series expansion in the other directions. By this approach, an angle-ply laminate may be composed of an arbitrary number of monoclinic layers and each layer may have different material property and thickness. This method guarantees continuous fields of all interlaminar stresses across interfaces between material layers. Numerical results are compared with those obtained from other methods. It is found that the theory provides a satisfactory approximation to the stress singularities near the free edges and ply cracks. Numerical solutions for antisymmetric laminates under extension and general laminates under shearing are new in the literature and can be used as benchmarks for validating new models. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1268&volume=133&issue=12&journal [...] [article] Free-edge and ply cracking effect in angle-ply laminated cloads omposites subjected to in-plane [texte imprimé] / Daxu Zhang, Auteur ; Jianqiao Ye, Auteur ; Dennis Lam, Auteur . - 2007 . - pp. 1268–1277.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1268–1277.
Mots-clés : Anisotropy Materials Laminates Edge effect Cracking Interfaces Stress analysis Résumé : This paper presents a semianalytical method for the prediction of interlaminar stresses and displacements near the free edges and ply cracks in general angle-ply laminates subjected to biaxial extensions and/or in plane shear deformation. The method is based on a state space representation of the three-dimensional equations of elasticity. Numerical solutions are obtained by using layer refinement in the through thickness direction and Fourier series expansion in the other directions. By this approach, an angle-ply laminate may be composed of an arbitrary number of monoclinic layers and each layer may have different material property and thickness. This method guarantees continuous fields of all interlaminar stresses across interfaces between material layers. Numerical results are compared with those obtained from other methods. It is found that the theory provides a satisfactory approximation to the stress singularities near the free edges and ply cracks. Numerical solutions for antisymmetric laminates under extension and general laminates under shearing are new in the literature and can be used as benchmarks for validating new models. ISSN : 0733-9399 En ligne : http://ascelibrary.org/action/showAbstract?page=1268&volume=133&issue=12&journal [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1278–1289.
Titre : Damping and viscoelastic dynamic response of RC flexural members strengthened with adhesively bonded composite materials Type de document : texte imprimé Auteurs : E. Hamed, Auteur ; O. Rabinovitch, Auteur Année de publication : 2007 Article en page(s) : pp.1278–1289. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Bonding Composite materials Damping Mathematical models Concrete reinforced Structural dynamics Viscoelasticity. Résumé : A theoretical approach for the dynamic viscoelastic response of reinforced concrete (RC) beams and one-way slabs strengthened with adhesively bonded composite materials is developed. The analytical model is based on variational principles, dynamic equilibrium, and compatibility of deformations between the structural components (RC beam/slab, adhesive, composite material). The model accounts for the deformability of the adhesive layer and for its high order stress and displacement fields. The equations of motion and the boundary, continuity, and initial conditions are derived via the extended Hamilton’s principle. The Kelvin-Voigt approach is adopted for the consideration of the viscoelastic response of the adhesive material and the internal damping in the composite material and the RC member. The Rayleigh damping model is used for the external viscous damping of the RC member. The dynamic governing equations are solved using the Newmark time integration and a multiple shooting algorithm is used for the solution in space. A numerical example is presented to examine the capabilities of the model, to highlight the unique phenomena associated with the viscoelastic response of the adhesive material, and to demonstrate its influence on the local and global behavior. The results obtained using the analytical model show that the viscoelastic response of the adhesive material may significantly modify the critical shear and peeling stresses at the interfaces of the adhesive layer. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Damping and viscoelastic dynamic response of RC flexural members strengthened with adhesively bonded composite materials [texte imprimé] / E. Hamed, Auteur ; O. Rabinovitch, Auteur . - 2007 . - pp.1278–1289.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1278–1289.
Mots-clés : Bonding Composite materials Damping Mathematical models Concrete reinforced Structural dynamics Viscoelasticity. Résumé : A theoretical approach for the dynamic viscoelastic response of reinforced concrete (RC) beams and one-way slabs strengthened with adhesively bonded composite materials is developed. The analytical model is based on variational principles, dynamic equilibrium, and compatibility of deformations between the structural components (RC beam/slab, adhesive, composite material). The model accounts for the deformability of the adhesive layer and for its high order stress and displacement fields. The equations of motion and the boundary, continuity, and initial conditions are derived via the extended Hamilton’s principle. The Kelvin-Voigt approach is adopted for the consideration of the viscoelastic response of the adhesive material and the internal damping in the composite material and the RC member. The Rayleigh damping model is used for the external viscous damping of the RC member. The dynamic governing equations are solved using the Newmark time integration and a multiple shooting algorithm is used for the solution in space. A numerical example is presented to examine the capabilities of the model, to highlight the unique phenomena associated with the viscoelastic response of the adhesive material, and to demonstrate its influence on the local and global behavior. The results obtained using the analytical model show that the viscoelastic response of the adhesive material may significantly modify the critical shear and peeling stresses at the interfaces of the adhesive layer. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1290–1301.
Titre : Behavior and failure strength of laminated glass beams Type de document : texte imprimé Auteurs : Foraboschi, Paolo, Auteur Année de publication : 2007 Article en page(s) : pp.1290–1301. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Failures Laminates Beams Glass Composite structures Construction materials Résumé : Despite the increased use of laminated glass (two monolithic layers of glass joined with an elastomeric interlayer—usually PVB—to form a unit) as a cladding material for architectural glazing applications and by now as a structural material, the mechanical properties and the structural capabilities of PVB laminated glass are not well known. This paper presents an analytical model that predicts stress development and ultimate strength of laminated glass beams involving a multilayered system that allows displacements in the shear flexible interlayer. The model may be applied to laminates of arbitrary shape and size under prevailing uniaxial bending. No specific simplifying assumption is made in formulating the procedure, so the modeling inaccuracy is marginal, as proved by comparing theoretical model predictions with test results. The model was then used for assessing the safety and predicting the failure strength of laminated glass products available in the architectural glass marketplace, in order to identify the basis for rational design with glass-polymer laminates. The closed form of the model permits us to both explain the behavior of laminated glass, and correlate the structural performance with the geometrical and mechanical parameters. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Behavior and failure strength of laminated glass beams [texte imprimé] / Foraboschi, Paolo, Auteur . - 2007 . - pp.1290–1301.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1290–1301.
Mots-clés : Failures Laminates Beams Glass Composite structures Construction materials Résumé : Despite the increased use of laminated glass (two monolithic layers of glass joined with an elastomeric interlayer—usually PVB—to form a unit) as a cladding material for architectural glazing applications and by now as a structural material, the mechanical properties and the structural capabilities of PVB laminated glass are not well known. This paper presents an analytical model that predicts stress development and ultimate strength of laminated glass beams involving a multilayered system that allows displacements in the shear flexible interlayer. The model may be applied to laminates of arbitrary shape and size under prevailing uniaxial bending. No specific simplifying assumption is made in formulating the procedure, so the modeling inaccuracy is marginal, as proved by comparing theoretical model predictions with test results. The model was then used for assessing the safety and predicting the failure strength of laminated glass products available in the architectural glass marketplace, in order to identify the basis for rational design with glass-polymer laminates. The closed form of the model permits us to both explain the behavior of laminated glass, and correlate the structural performance with the geometrical and mechanical parameters. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1302–1310
Titre : Behavior of a caisson subjected to a horizontal breaking wave force Type de document : texte imprimé Auteurs : Chi C. Tung, Auteur Année de publication : 2007 Article en page(s) : pp. 1302–1310 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Caissons Breakwaters Coastal environment Ocean water Résumé : In coastal waters, caissons are used as breakwaters. Under the action of breaking waves, some caissons are initiated into motion. This study is concerned with the following questions: For a caisson subjected to a breaking wave force, what are (1) the possible modes of response and (2) the conditions under which a caisson would be initiated into these modes? These questions have not been studied before. The actual response of a caisson that takes place in each mode is not addressed in this study. A caisson is modeled as a free-standing rigid body placed on a frictional base subjected to a concentrated horizontal force of short duration applied on the seaward side face of the caisson. The conditions for initiation of each mode of motion are derived using the three equations of motion of a plane rigid body. The results are given in explicit analytical forms and presented graphically. For simplicity, the effects of water surrounding the caisson are not included. Knowing the magnitude and location of the force, coefficient of friction, and aspect ratio of the body, the modes of motion of the body may be identified easily from the graphs. It is shown that under the action of a force, a body may undergo various types of motion and its behavior is quite different, depending on whether the line of action of the force is applied above or below the center of mass of the body. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Behavior of a caisson subjected to a horizontal breaking wave force [texte imprimé] / Chi C. Tung, Auteur . - 2007 . - pp. 1302–1310.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1302–1310
Mots-clés : Caissons Breakwaters Coastal environment Ocean water Résumé : In coastal waters, caissons are used as breakwaters. Under the action of breaking waves, some caissons are initiated into motion. This study is concerned with the following questions: For a caisson subjected to a breaking wave force, what are (1) the possible modes of response and (2) the conditions under which a caisson would be initiated into these modes? These questions have not been studied before. The actual response of a caisson that takes place in each mode is not addressed in this study. A caisson is modeled as a free-standing rigid body placed on a frictional base subjected to a concentrated horizontal force of short duration applied on the seaward side face of the caisson. The conditions for initiation of each mode of motion are derived using the three equations of motion of a plane rigid body. The results are given in explicit analytical forms and presented graphically. For simplicity, the effects of water surrounding the caisson are not included. Knowing the magnitude and location of the force, coefficient of friction, and aspect ratio of the body, the modes of motion of the body may be identified easily from the graphs. It is shown that under the action of a force, a body may undergo various types of motion and its behavior is quite different, depending on whether the line of action of the force is applied above or below the center of mass of the body. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1311–1325.
Titre : Application of structural health monitoring techniques to track structural changes in a retrofitted building based on ambient vibration Type de document : texte imprimé Auteurs : R. D. Nayeri, Auteur ; S. F. Masri, Auteur ; A. G. Chassiakos, Auteur Année de publication : 2007 Article en page(s) : pp.1311–1325. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Excitation Models Parameters Structural reliability Monitoring Retrofitting Vibration Résumé : One of the issues complicating the reliability assessment of structural health monitoring (SHM) methodologies slated for implementation under field conditions for damage detection in conjunction with typical infrastructure systems, is the paucity of experimental measurements from such structures. Particularly lacking is the availability of experimental data from physical structures, where quantifiable changes are made in the structure while SHM studies are being performed. That is precisely the focus of this paper. As a result of the 1994 Northridge Earthquake, a critical six-story building in the metropolitan Los Angeles region was found to need significant seismic mitigation measures. The building was instrumented with 14 state-of-the-art strong-motion accelerometers that were placed at various locations and in different orientations throughout the building. The instrumentation network was used to acquire extensive ambient vibration data sets at regular intervals that covered the whole construction phase, during which the building evolved from its original condition to the retrofitted status. This paper evaluates the usefulness of the natural excitation technique (NExT) in conjunction with the eigensystem realization algorithm (ERA) to determine the evolution of the modal properties of the subject building during the various phases of its retrofit process. Further, an assessment is made of the influence on the system identification results of significant user-selectable parameters such as: data window size and overlap; reference degree-of-freedom; and the dimensions of the associated Hankel matrix. In spite of the very low levels of ambient excitation, and the low spatial resolution of the sensors, use of the NExT/ERA algorithm yielded excellent identification results of the dominant modes of the building. Changes in the identified structural frequencies are correlated with the time that specific structural changes were made. It is shown that this unique collection of data can be extremely useful in calibrating the accuracy and sensitivity of various SHM schemes, as well as in providing useful identification parameter guidelines that can assist in the planning and deployment of sensor networks and associated data collection schemes for SHM applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Application of structural health monitoring techniques to track structural changes in a retrofitted building based on ambient vibration [texte imprimé] / R. D. Nayeri, Auteur ; S. F. Masri, Auteur ; A. G. Chassiakos, Auteur . - 2007 . - pp.1311–1325.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1311–1325.
Mots-clés : Excitation Models Parameters Structural reliability Monitoring Retrofitting Vibration Résumé : One of the issues complicating the reliability assessment of structural health monitoring (SHM) methodologies slated for implementation under field conditions for damage detection in conjunction with typical infrastructure systems, is the paucity of experimental measurements from such structures. Particularly lacking is the availability of experimental data from physical structures, where quantifiable changes are made in the structure while SHM studies are being performed. That is precisely the focus of this paper. As a result of the 1994 Northridge Earthquake, a critical six-story building in the metropolitan Los Angeles region was found to need significant seismic mitigation measures. The building was instrumented with 14 state-of-the-art strong-motion accelerometers that were placed at various locations and in different orientations throughout the building. The instrumentation network was used to acquire extensive ambient vibration data sets at regular intervals that covered the whole construction phase, during which the building evolved from its original condition to the retrofitted status. This paper evaluates the usefulness of the natural excitation technique (NExT) in conjunction with the eigensystem realization algorithm (ERA) to determine the evolution of the modal properties of the subject building during the various phases of its retrofit process. Further, an assessment is made of the influence on the system identification results of significant user-selectable parameters such as: data window size and overlap; reference degree-of-freedom; and the dimensions of the associated Hankel matrix. In spite of the very low levels of ambient excitation, and the low spatial resolution of the sensors, use of the NExT/ERA algorithm yielded excellent identification results of the dominant modes of the building. Changes in the identified structural frequencies are correlated with the time that specific structural changes were made. It is shown that this unique collection of data can be extremely useful in calibrating the accuracy and sensitivity of various SHM schemes, as well as in providing useful identification parameter guidelines that can assist in the planning and deployment of sensor networks and associated data collection schemes for SHM applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1326–1340.
Titre : Coupled macroelement model of soil-structure interaction in deep foundations Type de document : texte imprimé Auteurs : Changsoon Rha, Auteur ; Ertugrul Taciroglu, Auteur Année de publication : 2007 Article en page(s) : pp.1326–1340. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Soil-structure interaction Pile lateral loads Vertical loads Drilled shafts Piers Deep foundations Résumé : The principal objective of this study is the development and calibration of a macroelement model for soil-pile interaction under simultaneously applied lateral and vertical loads. Herein, we focus on cast-in-drilled-hole single piles that are partially or fully embedded in soil, which are frequently used as support structures in highway construction. The model is calibrated and verified using primarily three-dimensional finite-element simulations and, whenever possible, with experimental data obtained from open literature. These data indicate that lateral loads significantly affect the vertical response of single piles, whereas the converse coupling is negligible. The proposed macroelement model is capable of mimicking this phenomenon. As such, it is a computationally efficient alternative to finite-element analyses, and is feasible to be utilized in practical applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Coupled macroelement model of soil-structure interaction in deep foundations [texte imprimé] / Changsoon Rha, Auteur ; Ertugrul Taciroglu, Auteur . - 2007 . - pp.1326–1340.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1326–1340.
Mots-clés : Soil-structure interaction Pile lateral loads Vertical loads Drilled shafts Piers Deep foundations Résumé : The principal objective of this study is the development and calibration of a macroelement model for soil-pile interaction under simultaneously applied lateral and vertical loads. Herein, we focus on cast-in-drilled-hole single piles that are partially or fully embedded in soil, which are frequently used as support structures in highway construction. The model is calibrated and verified using primarily three-dimensional finite-element simulations and, whenever possible, with experimental data obtained from open literature. These data indicate that lateral loads significantly affect the vertical response of single piles, whereas the converse coupling is negligible. The proposed macroelement model is capable of mimicking this phenomenon. As such, it is a computationally efficient alternative to finite-element analyses, and is feasible to be utilized in practical applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1341–1351.
Titre : Simultaneous inverse identification of transient thermal properties and heat sources using sparse sensor information Type de document : texte imprimé Auteurs : Sanford W. Phillips, Auteur ; Wilkins Aquino, Auteur ; William M. Chirdon, Auteur Année de publication : 2007 Article en page(s) : pp.1341–1351. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Algorithms Heat transfer Thermal properties Résumé : A study is presented herein on the simultaneous inverse identification of transient internal heat generation, transient thermal diffusivity, and constant convection coefficients. The formulations of the direct and inverse problems are presented in the context of finite-element analysis and nonlinear optimization, respectively. A real-coded genetic algorithm was used to solve the inverse problem because of the global convergence properties of this optimization technique. It was found through numerical studies that heat generation and thermal conductivity as functions of time can be simultaneously and consistently estimated from sparse sensor information, as long as convection coefficients are known. However, treating convection coefficients as unknown may significantly affect the accuracy of the estimated thermal diffusivity function and to a lesser extent, the accuracy of the heat generation function. The numerical experiments showed, however, that the Biot number can be accurately estimated when the convection coefficients are not well known. These results can have wide and important implications in problems related to monitoring and quality control of structures. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Simultaneous inverse identification of transient thermal properties and heat sources using sparse sensor information [texte imprimé] / Sanford W. Phillips, Auteur ; Wilkins Aquino, Auteur ; William M. Chirdon, Auteur . - 2007 . - pp.1341–1351.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1341–1351.
Mots-clés : Algorithms Heat transfer Thermal properties Résumé : A study is presented herein on the simultaneous inverse identification of transient internal heat generation, transient thermal diffusivity, and constant convection coefficients. The formulations of the direct and inverse problems are presented in the context of finite-element analysis and nonlinear optimization, respectively. A real-coded genetic algorithm was used to solve the inverse problem because of the global convergence properties of this optimization technique. It was found through numerical studies that heat generation and thermal conductivity as functions of time can be simultaneously and consistently estimated from sparse sensor information, as long as convection coefficients are known. However, treating convection coefficients as unknown may significantly affect the accuracy of the estimated thermal diffusivity function and to a lesser extent, the accuracy of the heat generation function. The numerical experiments showed, however, that the Biot number can be accurately estimated when the convection coefficients are not well known. These results can have wide and important implications in problems related to monitoring and quality control of structures. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1358-1369
Titre : Analytical method for pullout of anchor from anchor–mortar–concrete anchorage system due tmortaro shear failure of Type de document : texte imprimé Auteurs : Zhimin Wu, Auteur ; Shutong Yang, Auteur ; Hu, Xiaozhi, Auteur Année de publication : 2007 Article en page(s) : pp.1358-1369 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Shear failure Cracking Pull-out resistance Bonding Mortars Résumé : Depending on the relevant material properties, failure of grouted anchors can take forms of pullout of concrete cones, debonding at either anchor–grout or grout–concrete interface, fracture of anchor and combination of some of these failure modes. Further, if the thickness of the grout layer is thin enough, the shear strength of the grout is relatively low or the anchor is in the form of a steel bar with ribs or spirals, the grout would be sheared off so that the anchor is pulled out. The present study presents an analytical method for the last scenario, i.e., anchor pullout from an anchor–mortar–concrete anchorage due to shear failure of mortar. Two different boundary conditions are considered: fixed bottom surface of concrete as Boundary 1, and top surface of concrete with uniform distributed force as Boundary 2. A shear-lag model was introduced to analyze the behaviors of the mortar and the interfacial properties of both the anchor–mortar and the mortar–concrete interfaces were also considered. Based on the deformation compatibilities of the interfaces and the mortar layer, the distributions of the tensile stresses in the anchor and shear stresses in the mortar along the embedment length were obtained analytically during different loading stages for both Boundaries 1 and 2. Moreover, the probabilities and sequences of shear cracks induced by the mortar failure were determined according to the boundary conditions and the comparison between the shear stresses at the loading and nonloading ends. Double shear crack propagation from both ends with different crack lengths was then investigated. Besides, the pullout load was expressed as a function of the shear crack lengths. Then the maximum load and the corresponding critical crack lengths were obtained by using the theories of extremum. Finally, a series of material, structural, and interfacial parameters were adopted to study their influences on the calculated results using the proposed method, including the critical crack lengths, initial cracking load and maximum pullout load. It was found that the initial cracking and maximum loads in Boundary 1 are larger than those in Boundary 2. However, as the longitudinal rigidity of the concrete increases, the values of the maximum pullout loads in both of the boundary conditions approach each other. It was also found that there exists an effective bonding length, beyond which the critical crack length and maximum pullout load are no longer increased. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Analytical method for pullout of anchor from anchor–mortar–concrete anchorage system due tmortaro shear failure of [texte imprimé] / Zhimin Wu, Auteur ; Shutong Yang, Auteur ; Hu, Xiaozhi, Auteur . - 2007 . - pp.1358-1369.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1358-1369
Mots-clés : Shear failure Cracking Pull-out resistance Bonding Mortars Résumé : Depending on the relevant material properties, failure of grouted anchors can take forms of pullout of concrete cones, debonding at either anchor–grout or grout–concrete interface, fracture of anchor and combination of some of these failure modes. Further, if the thickness of the grout layer is thin enough, the shear strength of the grout is relatively low or the anchor is in the form of a steel bar with ribs or spirals, the grout would be sheared off so that the anchor is pulled out. The present study presents an analytical method for the last scenario, i.e., anchor pullout from an anchor–mortar–concrete anchorage due to shear failure of mortar. Two different boundary conditions are considered: fixed bottom surface of concrete as Boundary 1, and top surface of concrete with uniform distributed force as Boundary 2. A shear-lag model was introduced to analyze the behaviors of the mortar and the interfacial properties of both the anchor–mortar and the mortar–concrete interfaces were also considered. Based on the deformation compatibilities of the interfaces and the mortar layer, the distributions of the tensile stresses in the anchor and shear stresses in the mortar along the embedment length were obtained analytically during different loading stages for both Boundaries 1 and 2. Moreover, the probabilities and sequences of shear cracks induced by the mortar failure were determined according to the boundary conditions and the comparison between the shear stresses at the loading and nonloading ends. Double shear crack propagation from both ends with different crack lengths was then investigated. Besides, the pullout load was expressed as a function of the shear crack lengths. Then the maximum load and the corresponding critical crack lengths were obtained by using the theories of extremum. Finally, a series of material, structural, and interfacial parameters were adopted to study their influences on the calculated results using the proposed method, including the critical crack lengths, initial cracking load and maximum pullout load. It was found that the initial cracking and maximum loads in Boundary 1 are larger than those in Boundary 2. However, as the longitudinal rigidity of the concrete increases, the values of the maximum pullout loads in both of the boundary conditions approach each other. It was also found that there exists an effective bonding length, beyond which the critical crack length and maximum pullout load are no longer increased. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1370-1377
Titre : Optimal discrete to continuous transfer for band limited inputs Type de document : texte imprimé Auteurs : Dionisio Bernal, Auteur Année de publication : 2007 Article en page(s) : pp. 1370-1377 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Structural dynamics Signal processing Discrete elements Parameters. Résumé : Central to the discrete to continuous (d2C) time transfer of state space models is the selection of an intersample parameterization of the input. At present the zero-order hold is widely used but the premise is unnecessarily crude in the typical situation where the input is not constant within the sampling intervals. The paper shows that the optimal d2C transfer for models obtained from low pass filtered observations is realized by treating the input as a sampled-modulated train of Dirac impulses, designated here as the band limited hold (BLH). The foregoing result rests primarily on the fact that the spectrum of the residual between the BLH reconstruction and the true input is zero in the first Nyquist band. The merit of the BLH is illustrated by contrasting its residue predictions with those obtained using the zero-order hold, the noncausal first-order hold, and a reconstruction based on a half time step forward shift of the zero-order hold premise. It is also shown that accuracy of the direct transmission matrix can be improved, over that realized from the d2C transfer, by computing it from constraints that connect it to the state space triplet {AcBcCc}. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?161365 [article] Optimal discrete to continuous transfer for band limited inputs [texte imprimé] / Dionisio Bernal, Auteur . - 2007 . - pp. 1370-1377.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp. 1370-1377
Mots-clés : Structural dynamics Signal processing Discrete elements Parameters. Résumé : Central to the discrete to continuous (d2C) time transfer of state space models is the selection of an intersample parameterization of the input. At present the zero-order hold is widely used but the premise is unnecessarily crude in the typical situation where the input is not constant within the sampling intervals. The paper shows that the optimal d2C transfer for models obtained from low pass filtered observations is realized by treating the input as a sampled-modulated train of Dirac impulses, designated here as the band limited hold (BLH). The foregoing result rests primarily on the fact that the spectrum of the residual between the BLH reconstruction and the true input is zero in the first Nyquist band. The merit of the BLH is illustrated by contrasting its residue predictions with those obtained using the zero-order hold, the noncausal first-order hold, and a reconstruction based on a half time step forward shift of the zero-order hold premise. It is also shown that accuracy of the direct transmission matrix can be improved, over that realized from the d2C transfer, by computing it from constraints that connect it to the state space triplet {AcBcCc}. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?161365
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1378–1387.
Titre : Efficient spreadsheet algorithm for first-order reliability method Type de document : texte imprimé Auteurs : B. K. Low, Auteur ; Wilson H. Tang, Auteur Année de publication : 2007 Article en page(s) : pp.1378–1387. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Probability Reliability Correlation Optimization Computer software Computation Résumé : A new spreadsheet-cell-object-oriented algorithm for the first-order reliability method is proposed and illustrated for cases with correlated nonnormals and explicit and implicit performance functions. The new approach differs from the writers earlier algorithm by obviating the need for computations of equivalent normal means and equivalent normal standard deviations. It obtains the solution faster and is more efficient, robust, and succinct. Other advantages include ease of initialization prior to constrained optimization, ease of randomization of initial values for checking robustness, and fewer required optimization constraints during spreadsheet-automated search for the design point. Two cases with implicit performance functions, namely an asymmetrically loaded beam on Winkler medium and a strut with complex supports are analyzed using the new approach and discussed. Comparisons are also made between the proposed approach and that based on Rosenblatt transformation. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Efficient spreadsheet algorithm for first-order reliability method [texte imprimé] / B. K. Low, Auteur ; Wilson H. Tang, Auteur . - 2007 . - pp.1378–1387.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1378–1387.
Mots-clés : Probability Reliability Correlation Optimization Computer software Computation Résumé : A new spreadsheet-cell-object-oriented algorithm for the first-order reliability method is proposed and illustrated for cases with correlated nonnormals and explicit and implicit performance functions. The new approach differs from the writers earlier algorithm by obviating the need for computations of equivalent normal means and equivalent normal standard deviations. It obtains the solution faster and is more efficient, robust, and succinct. Other advantages include ease of initialization prior to constrained optimization, ease of randomization of initial values for checking robustness, and fewer required optimization constraints during spreadsheet-automated search for the design point. Two cases with implicit performance functions, namely an asymmetrically loaded beam on Winkler medium and a strut with complex supports are analyzed using the new approach and discussed. Comparisons are also made between the proposed approach and that based on Rosenblatt transformation. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1388–1393.
Titre : Turbulence characteristics of open-channel flow with bed suction Type de document : texte imprimé Auteurs : Xingwei Chen, Auteur ; Yee-Meng Chiew, Auteur Année de publication : 2007 Article en page(s) : pp.1388–1393. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Turbulence Suction Open channel flow Velocity profile Reynolds stress Résumé : The influence of bed suction on the characteristics of turbulent open channel flow is studied in a laboratory flume using a two-component laser Doppler velocimeter. The experimental results show how bed suction significantly affects the mean flow properties, turbulence levels, and Reynolds stress distributions. The data reveal the presence of a more negative vertical (downward) velocity. The results also show how the horizontal and vertical turbulence intensities and Reynolds shear stresses respond to suction. All these properties are found to reduce with increasing relative suctions: decreasing more rapidly around the bed region than that near the free surface. In the downstream direction, the flow structure in the suction zone undergoes a process of rapid readjustment within a transitional region. Beyond this region, the turbulence flow structures asymptotes toward an “equilibrium” region. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Turbulence characteristics of open-channel flow with bed suction [texte imprimé] / Xingwei Chen, Auteur ; Yee-Meng Chiew, Auteur . - 2007 . - pp.1388–1393.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1388–1393.
Mots-clés : Turbulence Suction Open channel flow Velocity profile Reynolds stress Résumé : The influence of bed suction on the characteristics of turbulent open channel flow is studied in a laboratory flume using a two-component laser Doppler velocimeter. The experimental results show how bed suction significantly affects the mean flow properties, turbulence levels, and Reynolds stress distributions. The data reveal the presence of a more negative vertical (downward) velocity. The results also show how the horizontal and vertical turbulence intensities and Reynolds shear stresses respond to suction. All these properties are found to reduce with increasing relative suctions: decreasing more rapidly around the bed region than that near the free surface. In the downstream direction, the flow structure in the suction zone undergoes a process of rapid readjustment within a transitional region. Beyond this region, the turbulence flow structures asymptotes toward an “equilibrium” region. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1394–1400.
Titre : Large-deflection stability of slender beam-columns with both ends partially restrained against rotation Type de document : texte imprimé Auteurs : Vega-Posada, Carlos, Auteur ; Mauricio Areiza-Hurtado, Auteur ; Aristizábal-Ochoa, Darío J., Auteur Année de publication : 2007 Article en page(s) : pp.1394–1400. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Rotation Beam columns Buckling Deflection Postbuckling Résumé : The large-deflection analysis and postbuckling behavior of laterally braced or unbraced slender beam columns of symmetrical cross section subjected to end loads (forces and moments) with both ends partially restrained against rotation including the effects of out-of-plumbness is developed in a classical manner. The classical theory of the “Elastica” and the corresponding elliptical functions utilized herein are those presented previously by the senior writer. The proposed method can be used in the large-deflection elastic analysis and postbuckling behavior of slender beam columns with rigid, semirigid, and simple flexural connections and both ends. Only bending strains are considered, i.e., the effects of axial and shear strains are neglected. An example is included that shows the effects of flexible connections at both ends on the large-deflection analysis and postbuckling behavior of slender beam columns. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...] [article] Large-deflection stability of slender beam-columns with both ends partially restrained against rotation [texte imprimé] / Vega-Posada, Carlos, Auteur ; Mauricio Areiza-Hurtado, Auteur ; Aristizábal-Ochoa, Darío J., Auteur . - 2007 . - pp.1394–1400.
Mécanique appliquée
Langues : Anglais (eng)
in Journal of engineering mechanics > Vol. 133 N°11 (Novembre 2007) . - pp.1394–1400.
Mots-clés : Rotation Beam columns Buckling Deflection Postbuckling Résumé : The large-deflection analysis and postbuckling behavior of laterally braced or unbraced slender beam columns of symmetrical cross section subjected to end loads (forces and moments) with both ends partially restrained against rotation including the effects of out-of-plumbness is developed in a classical manner. The classical theory of the “Elastica” and the corresponding elliptical functions utilized herein are those presented previously by the senior writer. The proposed method can be used in the large-deflection elastic analysis and postbuckling behavior of slender beam columns with rigid, semirigid, and simple flexural connections and both ends. Only bending strains are considered, i.e., the effects of axial and shear strains are neglected. An example is included that shows the effects of flexible connections at both ends on the large-deflection analysis and postbuckling behavior of slender beam columns. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A12%281 [...]
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