Dépouillements

Progressive collapse of the world trade center / K. A. Seffen in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.125–132. Titre : Progressive collapse of the world trade center : Simple analysis Type de document : texte imprimé Auteurs : K. A. Seffen, Auteur Année de publication : 2008 Article en page(s) : pp.125–132. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Progressive  failure  Collapse  Residual  strength  Dynamic  analysis  Buildings  high-rise  New  York  New  York  City  Terrorism Résumé : The collapse behavior of the World Trade Center towers is considered formally as a propagating instability phenomenon. The application of associated concepts enables the residual capacities of both towers after the onset of collapse to be formally estimated. This information is combined into a simplified variable-mass collapse model of the overall dynamical behavior. The resulting, nonlinear governing equation of motion can be solved in closed form, to yield compact information about the overall collapse conditions. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2812 [...] [article] Progressive collapse of the world trade center : Simple analysis [texte imprimé] / K. A. Seffen, Auteur . - 2008 . - pp.125–132. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.125–132. Mots-clés : Progressive  failure  Collapse  Residual  strength  Dynamic  analysis  Buildings  high-rise  New  York  New  York  City  Terrorism Résumé : The collapse behavior of the World Trade Center towers is considered formally as a propagating instability phenomenon. The application of associated concepts enables the residual capacities of both towers after the onset of collapse to be formally estimated. This information is combined into a simplified variable-mass collapse model of the overall dynamical behavior. The resulting, nonlinear governing equation of motion can be solved in closed form, to yield compact information about the overall collapse conditions. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2812 [...]

Boundary finite-element method coupling finite-element method for steady-state analyses of dam-reservoir systems / S. C. Fan in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.133–142. Titre : Boundary finite-element method coupling finite-element method for steady-state analyses of dam-reservoir systems Type de document : texte imprimé Auteurs : S. C. Fan, Auteur ; S. M. Li, Auteur Année de publication : 2008 Article en page(s) : pp.133–142. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Dams  arch  Reservoirs  Coupling  Finite  element  method  Boundaries Résumé : The boundary finite-element method (BFEM) is extended for steady-state analyses of dam-reservoir system problems. In this study, the dam is assumed to be rigid and subjected to horizontal ground motions, and the liquid in the reservoir is assumed to be semiinfinite. The semiinfinite reservoir domain is partitioned into two subdomains: a near-field domain and a far-field domain. In it, the near-field domain is modeled by using the finite-element method (FEM), whereas the far-field domain is modeled by BFEM and is treated as a layered semiinfinite fluid domain. A BFEM/FEM coupling procedure is employed to solve the steady-state response of the reservoir. The coupling procedure is easy to implement and suitable for all frequencies, be it real or complex. The BFEM/FEM coupling procedure is validated in the frequency domain. Numerical results that are based on the present procedure are in good agreement with analytical and other available numerical solutions. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2813 [...] [article] Boundary finite-element method coupling finite-element method for steady-state analyses of dam-reservoir systems [texte imprimé] / S. C. Fan, Auteur ; S. M. Li, Auteur . - 2008 . - pp.133–142. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.133–142. Mots-clés : Dams  arch  Reservoirs  Coupling  Finite  element  method  Boundaries Résumé : The boundary finite-element method (BFEM) is extended for steady-state analyses of dam-reservoir system problems. In this study, the dam is assumed to be rigid and subjected to horizontal ground motions, and the liquid in the reservoir is assumed to be semiinfinite. The semiinfinite reservoir domain is partitioned into two subdomains: a near-field domain and a far-field domain. In it, the near-field domain is modeled by using the finite-element method (FEM), whereas the far-field domain is modeled by BFEM and is treated as a layered semiinfinite fluid domain. A BFEM/FEM coupling procedure is employed to solve the steady-state response of the reservoir. The coupling procedure is easy to implement and suitable for all frequencies, be it real or complex. The BFEM/FEM coupling procedure is validated in the frequency domain. Numerical results that are based on the present procedure are in good agreement with analytical and other available numerical solutions. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2813 [...]

Quantification and simulation of particle kinematics and local strains in granular materials using X-ray tomography imaging and discrete-element method / Yanrong Fu in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.143–154. Titre : Quantification and simulation of particle kinematics and local strains in granular materials using X-ray tomography imaging and discrete-element method Type de document : texte imprimé Auteurs : Yanrong Fu, Auteur ; Linbing Wang, Auteur ; Mehmet T. Tumay, Auteur Année de publication : 2008 Article en page(s) : pp.143–154. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Granular  materials  Three-dimensional  analysis  Deformation  Simulation  Radiography  Strain  Compression Résumé : Microfeatures of granular materials have significant effects on their macrobehaviors. Unfortunately, three-dimensional (3D) quantitative measurements of microfeatures are rare in literature because of the limitations of conventional techniques in obtaining microquantities such as microdisplacements and local strains. This paper presents a new method for quantifying the particle kinematics and local strains for a soft confined compression test using X-ray computed tomography and compares the experimental measurements with the simulated results using the discrete-element method (DEM). The experimental method can identify and recognize 3D individual particles automatically, which is essential for quantifying particle kinematics and local strains. 3D DEM simulations of the soft confined compression test were performed by using spherical particles and irregular particles. The simulated global deformations and particle translations that were based on irregular particles showed better agreement with the experimental measurements than those that were based on spherical particles. The simulated movements of spherical particles were more erratic, and the material composed of spherical particles showed larger vertical contraction and radial dilation. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2814 [...] [article] Quantification and simulation of particle kinematics and local strains in granular materials using X-ray tomography imaging and discrete-element method [texte imprimé] / Yanrong Fu, Auteur ; Linbing Wang, Auteur ; Mehmet T. Tumay, Auteur . - 2008 . - pp.143–154. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.143–154. Mots-clés : Granular  materials  Three-dimensional  analysis  Deformation  Simulation  Radiography  Strain  Compression Résumé : Microfeatures of granular materials have significant effects on their macrobehaviors. Unfortunately, three-dimensional (3D) quantitative measurements of microfeatures are rare in literature because of the limitations of conventional techniques in obtaining microquantities such as microdisplacements and local strains. This paper presents a new method for quantifying the particle kinematics and local strains for a soft confined compression test using X-ray computed tomography and compares the experimental measurements with the simulated results using the discrete-element method (DEM). The experimental method can identify and recognize 3D individual particles automatically, which is essential for quantifying particle kinematics and local strains. 3D DEM simulations of the soft confined compression test were performed by using spherical particles and irregular particles. The simulated global deformations and particle translations that were based on irregular particles showed better agreement with the experimental measurements than those that were based on spherical particles. The simulated movements of spherical particles were more erratic, and the material composed of spherical particles showed larger vertical contraction and radial dilation. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2814 [...]

Nonstationary response analysis of long span bridges under spatially varying differential support otions using continuous wavelet transform / Arunasis Chakraborty in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.155–162. Titre : Nonstationary response analysis of long span bridges under spatially varying differential support otions using continuous wavelet transform Type de document : texte imprimé Auteurs : Arunasis Chakraborty, Auteur ; Biswajit Basu, Auteur Année de publication : 2008 Article en page(s) : pp.155–162. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Stationary  processes  Bridges  span  Motion  Seismic  effects Résumé : An input-output relation for the nonstationary response of long-span bridges subjected to random differential support motions is proposed in the present study. The proposed methodology is more general than the existing ones, in the sense that it can evaluate nonstationarity in both the intensity and frequency content of the response statistics for spatially correlated multipoint random excitations. Furthermore, because the input-output relation is established through the transfer functions of dynamic systems, the proposed wavelet-based methodology can easily be used to predict the stochastic response of any structural systems in conjunction with available finite-element software. The input-output formulation is also not restricted to a particular wavelet basis function, since it has been derived by following a general wavelet-based description of input nonstationary processes. The bridge has been modeled as a simply supported beam with multispans in a finite-element framework to obtain the dynamic properties. With a modified form of the Littlewood-Paley (real part of harmonic) wavelet basis function, the support motion has been modeled as a summation of independent random processes in different nonoverlapping frequency bands. At each frequency band, the random process is expressed as a product of a stationary orthogonal process and a deterministic envelope function that depends on the scale. An exponential coherence function is used to model the spatial variation of the ground motion. The response statistics are obtained by using a random vibration formulation in the wavelet domain. The results demonstrate the effects of frequency nonstationarity on the response of a multispan bridge with closely spaced modes and excitation of higher modes locally in time. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2815 [...] [article] Nonstationary response analysis of long span bridges under spatially varying differential support otions using continuous wavelet transform [texte imprimé] / Arunasis Chakraborty, Auteur ; Biswajit Basu, Auteur . - 2008 . - pp.155–162. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.155–162. Mots-clés : Stationary  processes  Bridges  span  Motion  Seismic  effects Résumé : An input-output relation for the nonstationary response of long-span bridges subjected to random differential support motions is proposed in the present study. The proposed methodology is more general than the existing ones, in the sense that it can evaluate nonstationarity in both the intensity and frequency content of the response statistics for spatially correlated multipoint random excitations. Furthermore, because the input-output relation is established through the transfer functions of dynamic systems, the proposed wavelet-based methodology can easily be used to predict the stochastic response of any structural systems in conjunction with available finite-element software. The input-output formulation is also not restricted to a particular wavelet basis function, since it has been derived by following a general wavelet-based description of input nonstationary processes. The bridge has been modeled as a simply supported beam with multispans in a finite-element framework to obtain the dynamic properties. With a modified form of the Littlewood-Paley (real part of harmonic) wavelet basis function, the support motion has been modeled as a summation of independent random processes in different nonoverlapping frequency bands. At each frequency band, the random process is expressed as a product of a stationary orthogonal process and a deterministic envelope function that depends on the scale. An exponential coherence function is used to model the spatial variation of the ground motion. The response statistics are obtained by using a random vibration formulation in the wavelet domain. The results demonstrate the effects of frequency nonstationarity on the response of a multispan bridge with closely spaced modes and excitation of higher modes locally in time. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2815 [...]

Seismic energy dissipation of inelastic structures with tuned mass dampers / K. K. Wong in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.163–172. Titre : Seismic energy dissipation of inelastic structures with tuned mass dampers Type de document : texte imprimé Auteurs : K. K. Wong, Auteur Année de publication : 2008 Article en page(s) : pp.163–172. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Structural  dynamics  Earthquakes  Energy  Damping  Damage  Response  spectra  Seismic  effects Résumé : The energy transfer process of using a tuned mass damper (TMD) in improving the ability of inelastic structures to dissipate earthquake input energy is investigated. Inelastic structural behavior is modeled by using the force analogy method, which is the backbone of analytically characterizing the plastic energy dissipation in the structure. Numerical simulations are performed to study the energy responses of structures with and without TMD installed. The effectiveness of TMD in reducing energy responses is also studied by using plastic energy spectra for various structural yielding levels. Results show that the use of TMD enhances the ability of the structures to store larger amounts of energy inside the TMD that will be released at a later time in the form of damping energy when the response is not at a critical state, thereby increasing the damping energy dissipation while reducing the plastic energy dissipation. This reduction of plastic energy dissipation relates directly to the reduction of damage in the structure, and TMD is therefore concluded to be quite effective in protecting structures from suffering major damage during an earthquake. However, storing energy in the TMD is restricted if the structure becomes plastic at a small displacement level. In this case, the effectiveness of TMD diminishes, and the structural response becomes practically the same as those without TMD installed. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2816 [...] [article] Seismic energy dissipation of inelastic structures with tuned mass dampers [texte imprimé] / K. K. Wong, Auteur . - 2008 . - pp.163–172. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.163–172. Mots-clés : Structural  dynamics  Earthquakes  Energy  Damping  Damage  Response  spectra  Seismic  effects Résumé : The energy transfer process of using a tuned mass damper (TMD) in improving the ability of inelastic structures to dissipate earthquake input energy is investigated. Inelastic structural behavior is modeled by using the force analogy method, which is the backbone of analytically characterizing the plastic energy dissipation in the structure. Numerical simulations are performed to study the energy responses of structures with and without TMD installed. The effectiveness of TMD in reducing energy responses is also studied by using plastic energy spectra for various structural yielding levels. Results show that the use of TMD enhances the ability of the structures to store larger amounts of energy inside the TMD that will be released at a later time in the form of damping energy when the response is not at a critical state, thereby increasing the damping energy dissipation while reducing the plastic energy dissipation. This reduction of plastic energy dissipation relates directly to the reduction of damage in the structure, and TMD is therefore concluded to be quite effective in protecting structures from suffering major damage during an earthquake. However, storing energy in the TMD is restricted if the structure becomes plastic at a small displacement level. In this case, the effectiveness of TMD diminishes, and the structural response becomes practically the same as those without TMD installed. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2816 [...]

Sensitivity of seismic applications to different shape memory alloy models / Bassem Andrawes in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.173–183. Titre : Sensitivity of seismic applications to different shape memory alloy models Type de document : texte imprimé Auteurs : Bassem Andrawes, Auteur ; Reginald DesRoches, Auteur Année de publication : 2008 Article en page(s) : pp.173–183. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Shape  memory  effect  Elasticity  Earthquakes  Constitutive  models  Seismic  effects  Sensitivity  anlysis. Résumé : Shape memory alloys (SMAs) are known for their superelastic properties, which have been exploited in numerous applications in the biomedical, aerospace, and commercial fields. More recently, these materials have been evaluated for applications in the area of earthquake engineering. One key question that arises when using these materials is the appropriate constitutive material model to use to capture the highly nonlinear behavior of SMAs. This paper explores the effect of using different SMA constitutive models on the resulting response of systems using SMAs. A sensitivity analysis is conducted by using three SMA models with various levels of complexity. The models are implemented in a single-degree-of-freedom system and subjected to three groups of earthquake records with various characteristics. Considering a more accurate trend in modeling incomplete cycles in SMAs has little impact on the structural response. The strength degradation and residual deformation seem to be of more importance than the sublooping behavior. The response is more sensitive to the cyclic effects in the case of records with long durations or large intensities. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2817 [...] [article] Sensitivity of seismic applications to different shape memory alloy models [texte imprimé] / Bassem Andrawes, Auteur ; Reginald DesRoches, Auteur . - 2008 . - pp.173–183. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.173–183. Mots-clés : Shape  memory  effect  Elasticity  Earthquakes  Constitutive  models  Seismic  effects  Sensitivity  anlysis. Résumé : Shape memory alloys (SMAs) are known for their superelastic properties, which have been exploited in numerous applications in the biomedical, aerospace, and commercial fields. More recently, these materials have been evaluated for applications in the area of earthquake engineering. One key question that arises when using these materials is the appropriate constitutive material model to use to capture the highly nonlinear behavior of SMAs. This paper explores the effect of using different SMA constitutive models on the resulting response of systems using SMAs. A sensitivity analysis is conducted by using three SMA models with various levels of complexity. The models are implemented in a single-degree-of-freedom system and subjected to three groups of earthquake records with various characteristics. Considering a more accurate trend in modeling incomplete cycles in SMAs has little impact on the structural response. The strength degradation and residual deformation seem to be of more importance than the sublooping behavior. The response is more sensitive to the cyclic effects in the case of records with long durations or large intensities. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2817 [...]

Characteristics of steady horseshoe vortex system near junction of square cylinder and base plate / Chang Lin in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp. 184–197. Titre : Characteristics of steady horseshoe vortex system near junction of square cylinder and base plate Type de document : texte imprimé Auteurs : Chang Lin, Auteur ; Tsung Chun Ho, Auteur ; Subhasish Dey, Auteur Année de publication : 2008 Article en page(s) : pp. 184–197. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Vortices  Boundary  layers  Cylinders  Plates  Reynolds  number Résumé : This paper presents an experimental investigation on the characteristics of a horseshoe vortex system near the juncture of a square cylinder and a horizontal base plate, using particle image velocimetry and flow visualization technique. Experiments were conducted for Reynolds numbers (based on the free stream velocity and the width of square cylinder) ranging from 2.0×102 to 6.0×103 . The flow patterns are first classified into four major regimes: Steady horseshoe vortex system, periodic oscillation vortex system with small displacement, periodic breakaway vortex system, and irregular vortex system. The classifications can be demonstrated as a figure of Reynolds number versus the ratio of the height of square cylinder to undisturbed boundary layer thickness. The study then mainly focused on the characteristics of steady horseshoe vortex system (corresponding to Reynolds numbers ranging from 2.0×102 to 2.5×103 ). The nondimensional characteristics, including the horizontal and vertical distances from the primary vortex core to frontal face of the vertical square cylinder and bottom boundary of the base plate, respectively, the height of stagnation point at frontal face of the square cylinder, and the down-flow discharge as well as circulation of the primary vortex, all increase with increase of the ratio of the height of square cylinder to undisturbed boundary layer thickness. However, they all decrease with the increase of the aspect ratio (i.e., the height-to-width ratio) of the square cylinder. The study provides essential properties of a steady horseshoe vortex system and gives an insight for related engineering applications. It can be served as a basis for more complicated horseshoe vortex systems occurring at high Reynolds numbers. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2818 [...] [article] Characteristics of steady horseshoe vortex system near junction of square cylinder and base plate [texte imprimé] / Chang Lin, Auteur ; Tsung Chun Ho, Auteur ; Subhasish Dey, Auteur . - 2008 . - pp. 184–197. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp. 184–197. Mots-clés : Vortices  Boundary  layers  Cylinders  Plates  Reynolds  number Résumé : This paper presents an experimental investigation on the characteristics of a horseshoe vortex system near the juncture of a square cylinder and a horizontal base plate, using particle image velocimetry and flow visualization technique. Experiments were conducted for Reynolds numbers (based on the free stream velocity and the width of square cylinder) ranging from 2.0×102 to 6.0×103 . The flow patterns are first classified into four major regimes: Steady horseshoe vortex system, periodic oscillation vortex system with small displacement, periodic breakaway vortex system, and irregular vortex system. The classifications can be demonstrated as a figure of Reynolds number versus the ratio of the height of square cylinder to undisturbed boundary layer thickness. The study then mainly focused on the characteristics of steady horseshoe vortex system (corresponding to Reynolds numbers ranging from 2.0×102 to 2.5×103 ). The nondimensional characteristics, including the horizontal and vertical distances from the primary vortex core to frontal face of the vertical square cylinder and bottom boundary of the base plate, respectively, the height of stagnation point at frontal face of the square cylinder, and the down-flow discharge as well as circulation of the primary vortex, all increase with increase of the ratio of the height of square cylinder to undisturbed boundary layer thickness. However, they all decrease with the increase of the aspect ratio (i.e., the height-to-width ratio) of the square cylinder. The study provides essential properties of a steady horseshoe vortex system and gives an insight for related engineering applications. It can be served as a basis for more complicated horseshoe vortex systems occurring at high Reynolds numbers. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2818 [...]

Stochastic interpolation of spatial random fields by BF/MCF-ISM / Osamu Maruyama in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.198–205. Titre : Stochastic interpolation of spatial random fields by BF/MCF-ISM Type de document : texte imprimé Auteurs : Osamu Maruyama, Auteur ; Hoshiya, Masaru, Auteur Année de publication : 2008 Article en page(s) : pp.198–205. Note générale : Mécanique applqiuée Langues : Anglais (eng) Mots-clés : Bayesian  analysis  Monte  Carlo  method  Kalman  filters  Stochastic  processes Résumé : In the past, interpolation of random fields was successfully treated by Kriging methods for Gaussian fields, and by conditional simulation techniques for a class of non-Gaussian translation fields. Recently, bootstrap filter/Monte Carlo filter (BF/MCF) is extensively used for interpolation of general non-Gaussian fields. However, while BF/MCF is a versatile tool to interpolate non-Gaussian fields, that is an algorithm of generating a set of sample realizations of both a predicted state vector and a filtered state vector, the computational cost is expensive due to the required sample size. In order to reduce the required sample size, an importance sampling function derived from the updating theory of Gaussian fields is applied to the ordinary BF/MCF. Interpolation of spatial fields is first demonstrated by using numerically simulated data, and the BF/MCF incorporated with importance sampling technique (BF/MCF-ISM) for the state estimation of conditional non-Gaussian fields is performed with respect to its efficiency in variance reduction. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2819 [...] [article] Stochastic interpolation of spatial random fields by BF/MCF-ISM [texte imprimé] / Osamu Maruyama, Auteur ; Hoshiya, Masaru, Auteur . - 2008 . - pp.198–205. Mécanique applqiuée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.198–205. Mots-clés : Bayesian  analysis  Monte  Carlo  method  Kalman  filters  Stochastic  processes Résumé : In the past, interpolation of random fields was successfully treated by Kriging methods for Gaussian fields, and by conditional simulation techniques for a class of non-Gaussian translation fields. Recently, bootstrap filter/Monte Carlo filter (BF/MCF) is extensively used for interpolation of general non-Gaussian fields. However, while BF/MCF is a versatile tool to interpolate non-Gaussian fields, that is an algorithm of generating a set of sample realizations of both a predicted state vector and a filtered state vector, the computational cost is expensive due to the required sample size. In order to reduce the required sample size, an importance sampling function derived from the updating theory of Gaussian fields is applied to the ordinary BF/MCF. Interpolation of spatial fields is first demonstrated by using numerically simulated data, and the BF/MCF incorporated with importance sampling technique (BF/MCF-ISM) for the state estimation of conditional non-Gaussian fields is performed with respect to its efficiency in variance reduction. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2819 [...]

Dynamic thermal buckling of functionally graded spherical caps / N. Sundararajan in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.206–209. Titre : Dynamic thermal buckling of functionally graded spherical caps Type de document : texte imprimé Auteurs : N. Sundararajan, Auteur ; M. Ganapathi, Auteur Année de publication : 2008 Article en page(s) : pp.206–209. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Buckling  Shells  Thermal  factors  Finite  element  method Résumé : In the present work, dynamic buckling behavior of clamped functionally graded spherical caps suddenly exposed to a thermal field is studied using the finite-element procedure. The material properties are graded in the thickness direction. The temperature load corresponding to a sudden jump in the maximum average displacement in the time history of the shell structure is taken as the dynamic buckling temperature. Numerical study is carried out to highlight the influences of shell geometries and material gradient index on the critical buckling temperature. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2820 [...] [article] Dynamic thermal buckling of functionally graded spherical caps [texte imprimé] / N. Sundararajan, Auteur ; M. Ganapathi, Auteur . - 2008 . - pp.206–209. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.206–209. Mots-clés : Buckling  Shells  Thermal  factors  Finite  element  method Résumé : In the present work, dynamic buckling behavior of clamped functionally graded spherical caps suddenly exposed to a thermal field is studied using the finite-element procedure. The material properties are graded in the thickness direction. The temperature load corresponding to a sudden jump in the maximum average displacement in the time history of the shell structure is taken as the dynamic buckling temperature. Numerical study is carried out to highlight the influences of shell geometries and material gradient index on the critical buckling temperature. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2820 [...]

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