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Keywords: thin-wall, steel, limit state, imperfection, non-linear, finite element method, ANSYS.

Summary

The objective of the paper is to analyse the influence of initial imperfections on the behaviour of thin-walled girders welded of slender plate elements. In parallel with experiments conducted in Prague, one of the ultimate load tests was computer modelled [1]. In so doing, the girder was modelled, using the geometrically and materially non-linear variant of the shell finite element method, using the ANSYS program.

Thin-walled structures, i.e. systems made of slender plate elements are nowadays very frequently encountered in both building and bridge construction. Among their most frequently used types are steel plate girders with a slender web.

Considering a random influence of all initial imperfections, a sensitivity analysis of the effect of all imperfections on the load-carrying capacity of the girder was carried out. The measured initial curvatures of the webs of the test girders were expanded into double Fourier sine series. For a correct interpretation of the sensitivity analysis results, it is necessary to assume, monotonous dependences between input and output. It was therefore assumed that the value of the dominant shape of the initial curvature 1x1 (with the amplitude e1) would always be positive. The initial curvature shape was considered in three variants. For variants A and B, the initial curvature statistical characteristics were introduced according to measurements. For variant C, the same statistical characteristics were introduced for all the coefficients e1 to e9, with the aim to find out which of the initial curvature shapes influenced the output to the maximum extent. The random quantities e1 to e9 were there supposed to be statistically independent. The numerical simulation method latin hypercube sampling method (LHS) was used [2].

In this way, it was found out which initial imperfections exhibited the greatest influence on the load-carrying capacity. The main objective of the sensitivity analysis described in the paper is to study, for girders the web of which is under the action of combined shear and bending stress. The influence of the initial curvature of the web on (i) the static load-carrying capacity of the girders (which determines the ultimate limit state of the girder in the case of quasi-constant loading), (ii) the bending stresses at the toes of the fillet welds connecting the web with its peripheral elements (which play an important role in limit state of the girder in the case of its being subjected to load) are analysed. The results of the sensitivity analysis are given in the paper.

References

1: Z. Kala, J. Kala, M. Škaloud, B. Teplý, "Analysis of the Effect of Initial Curvature on the Stress State in Breathing Webs", In Proc. of International Colloquium, Budapest, 425-432, 2002.
2: D. Novák, B. Teplý, N. Shiraishi, "Sensitivity Analysis of Structures: A Review", in B.H.V. Topping, (Editor), "Developments in Computational Engineering Mechanics", Civil-Comp Press, Edinburgh, UK, pp 201-207, 1993. doi:10.4203/ccp.19.8.1

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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 26 Large-Deflection-Theory Analysis of the Effect of Web Initial Curvature on the Ultimate Strength of Steel Plate Girder J. Kala¹, Z. Kala¹, J. Melcher¹ and M. Škaloud² ¹Department of Structural Mechanics, Faculty of Civil Engineering, Brno University of Technology, Czech Republic ²Institute of Theoretical and Applied Mechanics, Czech Academy of Sciences, Prague, Czech Republic doi:10.4203/ccp.91.26 purchase the full-text of this paper Full Bibliographic Reference for this paper , "Large-Deflection-Theory Analysis of the Effect of Web Initial Curvature on the Ultimate Strength of Steel Plate Girder", 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 26, 2009. doi:10.4203/ccp.91.26 Keywords: thin-wall, steel, limit state, imperfection, non-linear, finite element method, ANSYS. Summary The objective of the paper is to analyse the influence of initial imperfections on the behaviour of thin-walled girders welded of slender plate elements. In parallel with experiments conducted in Prague, one of the ultimate load tests was computer modelled [1]. In so doing, the girder was modelled, using the geometrically and materially non-linear variant of the shell finite element method, using the ANSYS program. Thin-walled structures, i.e. systems made of slender plate elements are nowadays very frequently encountered in both building and bridge construction. Among their most frequently used types are steel plate girders with a slender web. Considering a random influence of all initial imperfections, a sensitivity analysis of the effect of all imperfections on the load-carrying capacity of the girder was carried out. The measured initial curvatures of the webs of the test girders were expanded into double Fourier sine series. For a correct interpretation of the sensitivity analysis results, it is necessary to assume, monotonous dependences between input and output. It was therefore assumed that the value of the dominant shape of the initial curvature 1x1 (with the amplitude e1) would always be positive. The initial curvature shape was considered in three variants. For variants A and B, the initial curvature statistical characteristics were introduced according to measurements. For variant C, the same statistical characteristics were introduced for all the coefficients e1 to e9, with the aim to find out which of the initial curvature shapes influenced the output to the maximum extent. The random quantities e1 to e9 were there supposed to be statistically independent. The numerical simulation method latin hypercube sampling method (LHS) was used [2]. In this way, it was found out which initial imperfections exhibited the greatest influence on the load-carrying capacity. The main objective of the sensitivity analysis described in the paper is to study, for girders the web of which is under the action of combined shear and bending stress. The influence of the initial curvature of the web on (i) the static load-carrying capacity of the girders (which determines the ultimate limit state of the girder in the case of quasi-constant loading), (ii) the bending stresses at the toes of the fillet welds connecting the web with its peripheral elements (which play an important role in limit state of the girder in the case of its being subjected to load) are analysed. The results of the sensitivity analysis are given in the paper. References 1 Z. Kala, J. Kala, M. Škaloud, B. Teplý, "Analysis of the Effect of Initial Curvature on the Stress State in Breathing Webs", In Proc. of International Colloquium, Budapest, 425-432, 2002. 2 D. Novák, B. Teplý, N. Shiraishi, "Sensitivity Analysis of Structures: A Review", in B.H.V. Topping, (Editor), "Developments in Computational Engineering Mechanics", Civil-Comp Press, Edinburgh, UK, pp 201-207, 1993. doi:10.4203/ccp.19.8.1 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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