Initial imperfections have long been acknowledged as having an effect on the behavior of shell structures, affecting both the global and local behavior. Yet, despite their significance, initial imperfections are rarely included in analytical models for pipelines. This is usually because of the complicated nature of initial imperfections, the difficulty in measuring them, and the small amount of available literature that describes their geometry. Some recent investigations at the University of Alberta in Edmonton have focused on the effect of initial imperfections on the behavior of segments of line pipe. Imperfections measured across the inside surface of pipe test specimens were incorporated into a finite element model that was developed to predict the experimental behavior of the specimens tested under combined loads of internal pressure, axial load and bending moment. Test-to-predicted ratios for the load carrying capacity of the test specimens had a mean value of 1.035 with a coefficient of variation of 0.047. The improvements in the accuracy of the finite element analysis models that include the initial imperfection pattern indicate their importance in modeling the experimental behavior. Once the importance of initial imperfections was established, idealized patterns were developed to simplify numerical modeling. This paper presents the results of different patterns investigated for both plain and girth-welded segments of line pipe and provides recommended simplified assumed initial imperfection patterns.
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e-mail: adorey@shaw.ca
e-mail: dwm@civil.ualberta.ca
e-mail: jjrcheng@civil.ualberta.ca
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November 2006
Technical Papers
Initial Imperfection Models for Segments of Line Pipe
Alfred B. Dorey,
Alfred B. Dorey
Department of Civil and Environmental Engineering,
e-mail: adorey@shaw.ca
University of Alberta
, Edmonton, Alberta, Canada T6G 2G7
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David W. Murray,
David W. Murray
Department of Civil and Environmental Engineering,
e-mail: dwm@civil.ualberta.ca
University of Alberta
, Edmonton, Alberta, Canada T6G 2G7
Search for other works by this author on:
J. J. Roger Cheng
J. J. Roger Cheng
Department of Civil and Environmental Engineering,
e-mail: jjrcheng@civil.ualberta.ca
University of Alberta
, Edmonton, Alberta, Canada T6G 2G7
Search for other works by this author on:
Alfred B. Dorey
Department of Civil and Environmental Engineering,
University of Alberta
, Edmonton, Alberta, Canada T6G 2G7e-mail: adorey@shaw.ca
David W. Murray
Department of Civil and Environmental Engineering,
University of Alberta
, Edmonton, Alberta, Canada T6G 2G7e-mail: dwm@civil.ualberta.ca
J. J. Roger Cheng
Department of Civil and Environmental Engineering,
University of Alberta
, Edmonton, Alberta, Canada T6G 2G7e-mail: jjrcheng@civil.ualberta.ca
J. Offshore Mech. Arct. Eng. Nov 2006, 128(4): 322-329 (8 pages)
Published Online: October 2, 2005
Article history
Received:
July 7, 2004
Revised:
October 2, 2005
Citation
Dorey, A. B., Murray, D. W., and Cheng, J. J. R. (October 2, 2005). "Initial Imperfection Models for Segments of Line Pipe." ASME. J. Offshore Mech. Arct. Eng. November 2006; 128(4): 322–329. https://doi.org/10.1115/1.2199565
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