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Keywords: imperfections, sensitivity, steel, structures, strut, variance.

Summary

The objective of the paper is to analyse the influence of initial imperfections on the ultimate limit state of slender struts. The struts were modelled, using the geometrically and materially non-linear variant of the shell finite element method, using the ANSYS program.

The Euler method based on proportional loading in combination with the Newton-Raphson method was used. The ultimate static load-carrying capacity was considered as the output analysed quantities. The load-carrying capacity was determined as the loading rate at which the matrix of tangential stiffness determinant Kt of the structure approaches zero with accurateness of 0.1%.

A comprehensive review of various sensitivity analysis methods is given e.g. in Saltelli [1]. Sobol's sensitivity analysis was used to determine the sensitivity of a strut's load-carrying capacity with respect to the variance of initial imperfections [2]. The influence of the variance of initial imperfections on the variance of ultimate static load-carrying capacity was calculated [2].

Sensitivity analysis provides information on which parameters are dominant and to which higher attention should be paid in (i) the preparation of input values, (ii) considerations and decision on improving technological processes and (iii) outlining and organization of checking activities [2]. Results of the sensitivity analysis provide steel manufacturers with valuable information on which imperfections to be controlled with increased attentiveness and accurateness [2].

The sensitivity analysis was evaluated on a computer by applying the numerical simulation Monte Carlo method and statistical characteristics evaluated, based on the experiments [3]. In each Monte Carlo method run the load-carrying capacity is evaluated using the model based on nonlinear variant of shell finite elements.

The dominant variable for struts with non-dimensional slenderness 1.1 is the amplitude of initial curvature of the strut axis e₀. In shorter struts with a non-dimensional slenderness of 0.7, the load-carrying capacity is most sensitive to the initial imperfection e₀, residual stress, yield strength, and flange thickness. The sensitivity analyses results clearly illustrate that the dominant variable for all of the monitored outputs is the amplitude of initial curvature of the strut axis e₀.

References

1: A. Saltelli, M. Ratto, T. Andress, F. Campolongo, J. Cariboni, D. Gatelli, M. Saisana, S. Tarantola, "Global Sensitivity Analysis Guiding the Worth of Scientific Models", New York: John Wiley and Sons, 2007.
2: Z. Kala, "Sensitivity Analysis of the Stability Problems of Thin-Walled Structures", Journal of Constructional Steel Research, 61(3), 415-422, March 2005. doi:10.1016/j.jcsr.2004.08.005
3: J. Melcher, Z. Kala, M. Holický, M. Fajkus, L. Rozlívka, "Design Characteristics of Structural Steels Based on Statistical Analysis of Metallurgical Products", Journal of Constructional Steel Research, 60, 795-808, 2004. doi:10.1016/S0143-974X(03)00144-5

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 91 PROCEEDINGS OF THE TWELFTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping, L.F. Costa Neves and R.C. Barros Paper 29 Buckling Sensitivity Analysis of Thin-Walled Structures using Shell Finite Elements and Nonlinear Computational Methods Z. Kala and J. Kala Department of Structure Mechanics, Faculty of Civil Engineering, Brno University of Technology, Czech Republic doi:10.4203/ccp.91.29 purchase the full-text of this paper Full Bibliographic Reference for this paper Z. Kala, J. Kala, "Buckling Sensitivity Analysis of Thin-Walled Structures using Shell Finite Elements and Nonlinear Computational Methods", in B.H.V. Topping, L.F. Costa Neves, R.C. Barros, (Editors), "Proceedings of the Twelfth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 29, 2009. doi:10.4203/ccp.91.29 Keywords: imperfections, sensitivity, steel, structures, strut, variance. Summary The objective of the paper is to analyse the influence of initial imperfections on the ultimate limit state of slender struts. The struts were modelled, using the geometrically and materially non-linear variant of the shell finite element method, using the ANSYS program. The Euler method based on proportional loading in combination with the Newton-Raphson method was used. The ultimate static load-carrying capacity was considered as the output analysed quantities. The load-carrying capacity was determined as the loading rate at which the matrix of tangential stiffness determinant Kt of the structure approaches zero with accurateness of 0.1%. A comprehensive review of various sensitivity analysis methods is given e.g. in Saltelli [1]. Sobol's sensitivity analysis was used to determine the sensitivity of a strut's load-carrying capacity with respect to the variance of initial imperfections [2]. The influence of the variance of initial imperfections on the variance of ultimate static load-carrying capacity was calculated [2]. Sensitivity analysis provides information on which parameters are dominant and to which higher attention should be paid in (i) the preparation of input values, (ii) considerations and decision on improving technological processes and (iii) outlining and organization of checking activities [2]. Results of the sensitivity analysis provide steel manufacturers with valuable information on which imperfections to be controlled with increased attentiveness and accurateness [2]. The sensitivity analysis was evaluated on a computer by applying the numerical simulation Monte Carlo method and statistical characteristics evaluated, based on the experiments [3]. In each Monte Carlo method run the load-carrying capacity is evaluated using the model based on nonlinear variant of shell finite elements. The dominant variable for struts with non-dimensional slenderness 1.1 is the amplitude of initial curvature of the strut axis e₀. In shorter struts with a non-dimensional slenderness of 0.7, the load-carrying capacity is most sensitive to the initial imperfection e₀, residual stress, yield strength, and flange thickness. The sensitivity analyses results clearly illustrate that the dominant variable for all of the monitored outputs is the amplitude of initial curvature of the strut axis e₀. References 1 A. Saltelli, M. Ratto, T. Andress, F. Campolongo, J. Cariboni, D. Gatelli, M. Saisana, S. Tarantola, "Global Sensitivity Analysis Guiding the Worth of Scientific Models", New York: John Wiley and Sons, 2007. 2 Z. Kala, "Sensitivity Analysis of the Stability Problems of Thin-Walled Structures", Journal of Constructional Steel Research, 61(3), 415-422, March 2005. doi:10.1016/j.jcsr.2004.08.005 3 J. Melcher, Z. Kala, M. Holický, M. Fajkus, L. Rozlívka, "Design Characteristics of Structural Steels Based on Statistical Analysis of Metallurgical Products", Journal of Constructional Steel Research, 60, 795-808, 2004. doi:10.1016/S0143-974X(03)00144-5 purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £140 +P&P)
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