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Increasing the design life of welded tubular piles
Preliminary tests were performed on specimens in which residual stresses were artificially introduced by mechanical methods, as opposed to welding. Stress waveforms simulating those during pile driving which generated stresses equivalent to 95 and 105 % of the yield strength were applied to these specimens. Residual stress relief occurred during the initial cycle, being 56 and 59 % respectively for the above pile driving conditions. Continuing stress cycles up to 1000 produced only a further 12 % of stress relief for the lower stress, rising to 26 % for the above yield stress. Very similar results were produced for waveforms having dwell time durations of 4 and 120 ms, indicating that stress relief is effectively instantaneous. Unfortunately the stresses generated during pile driving of full scale welded piles in both the 19 and 30 mm wall thickness test piles were lower than those predicted and were insufficient to produce significant stress relief in the vicinity of both the single V and double V welds. Consequently the fatigue resistance of the driven piling welds appears to be inferior to that of the non-driven welds. There was some indication that the thicker piling has a slightly inferior fatigue resistance. Because the application of above yield stresses does not always occur during piling operations it cannot be assumed that, in practice a beneficial effect of pile driving will occur.
Increasing the design life of welded tubular piles
Preliminary tests were performed on specimens in which residual stresses were artificially introduced by mechanical methods, as opposed to welding. Stress waveforms simulating those during pile driving which generated stresses equivalent to 95 and 105 % of the yield strength were applied to these specimens. Residual stress relief occurred during the initial cycle, being 56 and 59 % respectively for the above pile driving conditions. Continuing stress cycles up to 1000 produced only a further 12 % of stress relief for the lower stress, rising to 26 % for the above yield stress. Very similar results were produced for waveforms having dwell time durations of 4 and 120 ms, indicating that stress relief is effectively instantaneous. Unfortunately the stresses generated during pile driving of full scale welded piles in both the 19 and 30 mm wall thickness test piles were lower than those predicted and were insufficient to produce significant stress relief in the vicinity of both the single V and double V welds. Consequently the fatigue resistance of the driven piling welds appears to be inferior to that of the non-driven welds. There was some indication that the thicker piling has a slightly inferior fatigue resistance. Because the application of above yield stresses does not always occur during piling operations it cannot be assumed that, in practice a beneficial effect of pile driving will occur.
Increasing the design life of welded tubular piles
Steigerung der Lebensdauer geschweißter Rundstützen
Priest, A. (author) / Harris, D. (author)
1998
54 Seiten, 29 Bilder, 13 Tabellen, 6 Quellen
Report
English
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