0
Strutures, Safety and Reliability

Fatigue Testing and S-N Data for Fatigue Analysis of Piles

[+] Author and Article Information
Inge Lotsberg, Stig Wästberg, Hugo Ulle

 DNV Veritasveien 1, 1322 Høvik Norway

Per Haagensen

 NTNU, 7491 Tronolheim, Norway

Michael E. Hall

 ConocoPhillips Norge AS, Ekotiskveien 35, Tananger 4064 Stavanger, Norway

J. Offshore Mech. Arct. Eng 132(4), 041602 (Sep 23, 2010) (7 pages) doi:10.1115/1.4001417 History: Received September 20, 2008; Revised December 16, 2009; Published September 23, 2010; Online September 23, 2010

Design S-N curves in design codes are based on fatigue test data, where the stress cycle is under external tension load. It is observed that during pile driving most of the stress cycle is compressive and the design procedure used for fatigue analysis of piles might therefore be conservative. In order to investigate this further, it was proposed to perform laboratory fatigue testing of specimens that are representative for butt welds in piles under relevant loading conditions. In the present project 30 test specimens made from welded plates were fatigue tested at different loading conditions to assess effect of compressive stress cycles as compared with tensile stress cycles. In 2006, the Edda tripod in block 2/7 was taken ashore. This platform has been in service since 1976 and the piles are considered to be representative for the piles installed in the North Sea jacket structures during the 1970s. Therefore it was suggested to investigate the pile weld at the sea bed in detail to assess the stress due to fabrication and 30 years of in-service life and the residual fatigue life of the pile. Six test specimens made from the Edda pile were fatigue tested. The results from the assessment and the fatigue testing are presented in this paper.

FIGURES IN THIS ARTICLE
<>
Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Shake-down in a ship structure

Grahic Jump Location
Figure 2

Section of pile from Edda platform

Grahic Jump Location
Figure 3

Macrograph of section Edda pile

Grahic Jump Location
Figure 4

Section through weld

Grahic Jump Location
Figure 5

Strain gauges on specimen

Grahic Jump Location
Figure 6

Fatigue test data without including cycles from pile driving simulation

Grahic Jump Location
Figure 7

Fatigue test data including number of cycles from pile driving as derived from Eq. 3

Grahic Jump Location
Figure 8

Photo of fractured specimen 3–5

Grahic Jump Location
Figure 9

Test data from the specimens from the Edda pile

Grahic Jump Location
Figure 10

Calculated standard deviation as function of reduction factor on compressive stress

Grahic Jump Location
Figure 11

Resulting S-N data for reduction factor α=0.8 in Eq. 6

Grahic Jump Location
Figure 12

Stress cycling in actual pile

Grahic Jump Location
Figure 13

Stress cycling in test specimen

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In