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Roure Fernández Francisco - One of the best experts on this subject based on the ideXlab platform.
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Imperfection Amplitudes for nonlinear analysis of open thin-walled steel cross-sections used in rack column uprights
'Elsevier BV', 2014Co-Authors: Pastor Artigues, María Magdalena, Casafont Ribera Miguel, Bonada Bo Jordi, Roure Fernández FranciscoAbstract:When numerical models are used to predict behaviour of open thin-walled steel cross-sections, the nonlinear analysis results can be influenced by the magnitudes introduced as initial Imperfection. At present, a wide range of values is considered in research concerning this topic. This paper explores up to what point the nonlinear analysis results are sensitive to the choice of Imperfection magnitudes and attempt to refine the spectrum of magnitudes that should be used. The study focuses on rack uprights (with and without perforations) under compression and the numerical model has been validated with experimental tests conducted by the authors. Three different column lengths have been selected to reproduce a mainly local, distortional and global failure mode, so that coupled instabilities have not to be considered in this case. The results show that the ultimate load and collapse mode are both sensitive to Imperfection Amplitude, mainly in the case of distortional buckling.Peer Reviewe
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Imperfection Amplitudes for nonlinear analysis of open thin-walled steel cross-sections used in rack column uprights
'Elsevier BV', 2014Co-Authors: Pastor Artigues, María Magdalena, Casafont Ribera Miguel, Bonada Bo Jordi, Roure Fernández FranciscoAbstract:When numerical models are used to predict behaviour of open thin-walled steel cross-sections, the nonlinear analysis results can be influenced by the magnitudes introduced as initial Imperfection. At present, a wide range of values is considered in research concerning this topic. This paper explores up to what point the nonlinear analysis results are sensitive to the choice of Imperfection magnitudes and attempt to refine the spectrum of magnitudes that should be used. The study focuses on rack uprights (with and without perforations) under compression and the numerical model has been validated with experimental tests conducted by the authors. Three different column lengths have been selected to reproduce a mainly local, distortional and global failure mode, so that coupled instabilities have not to be considered in this case. The results show that the ultimate load and collapse mode are both sensitive to Imperfection Amplitude, mainly in the case of distortional buckling.Peer ReviewedPostprint (published version
Ph Van Bogaert - One of the best experts on this subject based on the ideXlab platform.
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LOAD-CARRYING CAPACITY OF UNBRACED HISTORIC CONCRETE TIED- ARCH BRIDGES Load-carrying capacity of unbraced historic concrete tied-arch bridges
2020Co-Authors: Ph Van BogaertAbstract:ABSTRACT The stability assessment of concrete arch bridges is considered for 4 heritage examples, having no upper wind bracing. The relevance of this stability problem is due to the need of evaluating the load carrying capacity of older structures and the increase of design loads, or in case of possible defects. The simplified method for verifying second order effects of Eurocode 2, based on limiting values of the slenderness factor, suggests that all 4 cases show nonlinear behavior. The latter has been taken into account by applying the reduced stiffness method, which seems appropriate for solid structures as concrete arches. This has been combined with geometric nonlinear simulations, also including Imperfections. However, the relation between the critical load factor and the arch slenderness fails to render clear results. Although the number of bridge cases is limited, it appears that the slenderness may not be an adequate factor for determining the arch stability and failure. The effect of Imperfections, corresponding to the fundamental mode shape, has been found to be similar for at least 2 completely different bridges. A low value of the Imperfection Amplitude decreases the failure load in an identical manner, suggesting that the effect may be defined in a general way, reducing failure loads by a constant factor. ABSTRACT The stability assessment of concrete arch bridges is considered for 4 heritage examples, having no upper wind bracing. The relevance of this stability problem is due to the need of evaluating the load carrying capacity of older structures and the increase of design loads, or in case of possible defects. The simplified method for verifying second order effects of Eurocode 2, based on limiting values of the slenderness factor, suggests that all 4 cases show nonlinear behavior. The latter has been taken into account by applying the reduced stiffness method, which seems appropriate for solid structures as concrete arches. This has been combined with geometric nonlinear simulations, also including Imperfections. However, the relation between the critical load factor and the arch slenderness fails to render clear results. Although the number of bridge cases is limited, it appears that the slenderness may not be an adequate factor for determining the arch stability and failure. The effect of Imperfections, corresponding to the fundamental mode shape, has been found to be similar for at least 2 completely different bridges. A low value of the Imperfection Amplitude decreases the failure load in an identical manner, suggesting that the effect may be defined in a general way, reducing failure loads by a constant factor
Pu Tsai - One of the best experts on this subject based on the ideXlab platform.
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dynamic buckling of an imperfect composite circular cylindrical shell
Computers & Structures, 1993Co-Authors: D Shaw, Y L Shen, Pu TsaiAbstract:Abstract The dynamic stability of an imperfect fiber reinforced composite cylindrical shells under axial or/and torsional impulsive load in the form of a step function is investigated. Donnell-von Karman type nonlinear equations are derived for the initially imperfect laminated composite cylinder. Two buckling criteria are used for comparison. Critical loads are computed for different Imperfection parameters. The sensitivity is established through plots of critical loads versus Imperfection Amplitude. The larger the drop in critical load value with increasing Amplitude, the greater the sensitivity. Compared with the static case, there is a significant reduction of the dynamic buckling load subject in axial direction. For the torsional load, no significant reduction has been found. Comparing dynamic buckling loads obtained by using the Simitses criteria and by using the Budiansky and Roth criteria, with the Simitses criteria one can get conservative results.
Pastor Artigues, María Magdalena - One of the best experts on this subject based on the ideXlab platform.
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Imperfection Amplitudes for nonlinear analysis of open thin-walled steel cross-sections used in rack column uprights
'Elsevier BV', 2014Co-Authors: Pastor Artigues, María Magdalena, Casafont Ribera Miguel, Bonada Bo Jordi, Roure Fernández FranciscoAbstract:When numerical models are used to predict behaviour of open thin-walled steel cross-sections, the nonlinear analysis results can be influenced by the magnitudes introduced as initial Imperfection. At present, a wide range of values is considered in research concerning this topic. This paper explores up to what point the nonlinear analysis results are sensitive to the choice of Imperfection magnitudes and attempt to refine the spectrum of magnitudes that should be used. The study focuses on rack uprights (with and without perforations) under compression and the numerical model has been validated with experimental tests conducted by the authors. Three different column lengths have been selected to reproduce a mainly local, distortional and global failure mode, so that coupled instabilities have not to be considered in this case. The results show that the ultimate load and collapse mode are both sensitive to Imperfection Amplitude, mainly in the case of distortional buckling.Peer Reviewe
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Imperfection Amplitudes for nonlinear analysis of open thin-walled steel cross-sections used in rack column uprights
'Elsevier BV', 2014Co-Authors: Pastor Artigues, María Magdalena, Casafont Ribera Miguel, Bonada Bo Jordi, Roure Fernández FranciscoAbstract:When numerical models are used to predict behaviour of open thin-walled steel cross-sections, the nonlinear analysis results can be influenced by the magnitudes introduced as initial Imperfection. At present, a wide range of values is considered in research concerning this topic. This paper explores up to what point the nonlinear analysis results are sensitive to the choice of Imperfection magnitudes and attempt to refine the spectrum of magnitudes that should be used. The study focuses on rack uprights (with and without perforations) under compression and the numerical model has been validated with experimental tests conducted by the authors. Three different column lengths have been selected to reproduce a mainly local, distortional and global failure mode, so that coupled instabilities have not to be considered in this case. The results show that the ultimate load and collapse mode are both sensitive to Imperfection Amplitude, mainly in the case of distortional buckling.Peer ReviewedPostprint (published version
D Shaw - One of the best experts on this subject based on the ideXlab platform.
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dynamic buckling of an imperfect composite circular cylindrical shell
Computers & Structures, 1993Co-Authors: D Shaw, Y L Shen, Pu TsaiAbstract:Abstract The dynamic stability of an imperfect fiber reinforced composite cylindrical shells under axial or/and torsional impulsive load in the form of a step function is investigated. Donnell-von Karman type nonlinear equations are derived for the initially imperfect laminated composite cylinder. Two buckling criteria are used for comparison. Critical loads are computed for different Imperfection parameters. The sensitivity is established through plots of critical loads versus Imperfection Amplitude. The larger the drop in critical load value with increasing Amplitude, the greater the sensitivity. Compared with the static case, there is a significant reduction of the dynamic buckling load subject in axial direction. For the torsional load, no significant reduction has been found. Comparing dynamic buckling loads obtained by using the Simitses criteria and by using the Budiansky and Roth criteria, with the Simitses criteria one can get conservative results.