STP918

    Observations, Predictions, and Prevention of Fatigue Cracking in Offshore Structures

    Published: Jan 1986


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    Abstract

    In the past, during transit of jack-up offshore drill rigs, vortex shedding caused the initiation of fatigue cracks at certain details. The problem was defined as an interaction of cyclic stresses introduced by column vortex shedding and tensile residual stresses in the details. The paper outlines two simultaneous approaches to solution of the problem: (1) elimination of vortex shedding through structural modifications, that is, addition of helical strakes or spoilers, and (2) determination, by experiment, whether thermal stress-relief was beneficial. Also reviewed are the development and experimental corroboration of a local-strain life prediction method applicable to this and other structural fatigue problems.

    Keywords:

    crack initiation, design, fatigue life prediction, fatigue of metals, fatigue tests, local strain, offshore platforms, residual stress, stress concentration, stress relief, vortex shedding


    Author Information:

    Reemsnyder, HS
    Senior research fellow, Bethlehem Steel Corporation, BethlehemPA,


    Paper ID: STP19331S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP19331S


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