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Error assessment for spectral representation method in random field simulation / Yufeng Gao in Journal of engineering mechanics, Vol. 138 N° 6 (Juin 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 6 (Juin 2012) . - pp.711-715 Titre : Error assessment for spectral representation method in random field simulation Type de document : texte imprimé Auteurs : Yufeng Gao, Auteur ; Yongxin Wu, Auteur ; Yuanqiang Cai, Auteur Année de publication : 2012 Article en page(s) : pp.711-715 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Random  field  simulation  Spectral  representation  method  Error  assessment Résumé : Random fields, such as the wind velocity field and the seismic ground motion field, are usually simulated by the spectral representation method (SRM). The SRM mainly relies on two methods: the random amplitudes method and the random phases method. However, the temporal statistics estimated from one SRM-simulated sample process differs from the target characteristics. Such differences can usually be assessed by the statistical errors, i. e., bias errors and stochastic errors. The closed-form solutions of statistical errors produced by random phases method have been given. This paper gives the closed-form solutions of statistical errors produced by the random phases methods and compares the statistical errors produced by both methods. The comparison of the stochastic errors of power spectral density functions produced by different methods demonstrates that (1) the random amplitudes method exhibits higher but more uniformly distributed stochastic errors than the random phases method; and (2) the stochastic errors produced by the random phases method are dependent on the decomposition method, whereas those produced by the random amplitudes method are not. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000379 [article] Error assessment for spectral representation method in random field simulation [texte imprimé] / Yufeng Gao, Auteur ; Yongxin Wu, Auteur ; Yuanqiang Cai, Auteur . - 2012 . - pp.711-715. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 6 (Juin 2012) . - pp.711-715 Mots-clés : Random  field  simulation  Spectral  representation  method  Error  assessment Résumé : Random fields, such as the wind velocity field and the seismic ground motion field, are usually simulated by the spectral representation method (SRM). The SRM mainly relies on two methods: the random amplitudes method and the random phases method. However, the temporal statistics estimated from one SRM-simulated sample process differs from the target characteristics. Such differences can usually be assessed by the statistical errors, i. e., bias errors and stochastic errors. The closed-form solutions of statistical errors produced by random phases method have been given. This paper gives the closed-form solutions of statistical errors produced by the random phases methods and compares the statistical errors produced by both methods. The comparison of the stochastic errors of power spectral density functions produced by different methods demonstrates that (1) the random amplitudes method exhibits higher but more uniformly distributed stochastic errors than the random phases method; and (2) the stochastic errors produced by the random phases method are dependent on the decomposition method, whereas those produced by the random amplitudes method are not. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000379

Simplified approach for reliability-based design against basal-heave failure in braced excavations considering spatial effect / Zhe Luo in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 4 (Avril 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 4 (Avril 2012) . - pp. 441–450 Titre : Simplified approach for reliability-based design against basal-heave failure in braced excavations considering spatial effect Type de document : texte imprimé Auteurs : Zhe Luo, Auteur ; Sez Atamturktur, Auteur ; Yuanqiang Cai, Auteur Année de publication : 2012 Article en page(s) : pp. 441–450 Note générale : Géologie appliquée Langues : Anglais (eng) Mots-clés : Basal-heave  Excavation  Factor  of  safety  First-order  reliability  method  Probability  Random  field  Spatial  variability Résumé : This paper presents a simplified approach for reliability analysis of basal heave in a braced excavation considering the spatial variability of soil parameters, The first-order reliability method (FORM) with a variance reduction technique is employed to model the spatial variability in lieu of the conventional random field modeling (RFM). The proposed approach yields results that are comparable with those obtained using the conventional RFM approach that relies on Monte Carlo simulation. The proposed approach requires much less computational effort, is easy to use, and has potential as a practical tool for reliability-based design that has to deal with spatial variability of soils. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000621 [article] Simplified approach for reliability-based design against basal-heave failure in braced excavations considering spatial effect [texte imprimé] / Zhe Luo, Auteur ; Sez Atamturktur, Auteur ; Yuanqiang Cai, Auteur . - 2012 . - pp. 441–450. Géologie appliquée Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 4 (Avril 2012) . - pp. 441–450 Mots-clés : Basal-heave  Excavation  Factor  of  safety  First-order  reliability  method  Probability  Random  field  Spatial  variability Résumé : This paper presents a simplified approach for reliability analysis of basal heave in a braced excavation considering the spatial variability of soil parameters, The first-order reliability method (FORM) with a variance reduction technique is employed to model the spatial variability in lieu of the conventional random field modeling (RFM). The proposed approach yields results that are comparable with those obtained using the conventional RFM approach that relies on Monte Carlo simulation. The proposed approach requires much less computational effort, is easy to use, and has potential as a practical tool for reliability-based design that has to deal with spatial variability of soils. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000621

Vertical vibrations of a rigid foundation embedded in a poroelastic half space / Yuanqiang Cai in Journal of engineering mechanics, Vol. 136 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 136 N° 3 (Mars 2010) . - pp. 390-398 Titre : Vertical vibrations of a rigid foundation embedded in a poroelastic half space Type de document : texte imprimé Auteurs : Yuanqiang Cai, Auteur ; Hu, Xiuqing, Auteur Article en page(s) : pp. 390-398 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Soil-structure  interactions  Vibration  Foundations  Half  space  Poroelasticity. Résumé : This paper considers the steady-state vertical vibrations of a rigid, cylindrical massive foundation embedded in a poroelastic soil. The foundation is subjected to time-harmonic vertical loading and is perfectly bonded to the surrounding soil. The contact surface between the foundation and the soil is assumed to be smooth and fully permeable. Biot's poroelastodynamic theory is used in the analysis. The soil underlying the foundation base is assumed to be a homogeneous poroelastic half space while the soil along the side of the foundation is assumed to consist of a series of infinitesimally thin layers. The dynamic interaction problem is solved by a simplified analytical method. The accuracy of the present solution is verified by comparisons with existing solutions for both elastodynamic and poroelastodynamic interaction problems. Selected numerical results for the vertical dynamic impedance and response factor of the rigid foundation are presented to demonstrate the influence of nondimensional frequency of excitation, depth ratio, mass ratio, shear modulus of the backfill, and poroelastic material properties on dynamic interaction between an embedded foundation and a poroelastic half space. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&ONLINE=YES&s [...] [article] Vertical vibrations of a rigid foundation embedded in a poroelastic half space [texte imprimé] / Yuanqiang Cai, Auteur ; Hu, Xiuqing, Auteur . - pp. 390-398. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 136 N° 3 (Mars 2010) . - pp. 390-398 Mots-clés : Soil-structure  interactions  Vibration  Foundations  Half  space  Poroelasticity. Résumé : This paper considers the steady-state vertical vibrations of a rigid, cylindrical massive foundation embedded in a poroelastic soil. The foundation is subjected to time-harmonic vertical loading and is perfectly bonded to the surrounding soil. The contact surface between the foundation and the soil is assumed to be smooth and fully permeable. Biot's poroelastodynamic theory is used in the analysis. The soil underlying the foundation base is assumed to be a homogeneous poroelastic half space while the soil along the side of the foundation is assumed to consist of a series of infinitesimally thin layers. The dynamic interaction problem is solved by a simplified analytical method. The accuracy of the present solution is verified by comparisons with existing solutions for both elastodynamic and poroelastodynamic interaction problems. Selected numerical results for the vertical dynamic impedance and response factor of the rigid foundation are presented to demonstrate the influence of nondimensional frequency of excitation, depth ratio, mass ratio, shear modulus of the backfill, and poroelastic material properties on dynamic interaction between an embedded foundation and a poroelastic half space. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&ONLINE=YES&s [...]