The important issue of the influence of probabilistic fiber composite strength on the reliability assessment of a composite production riser is studied. Based on composite micromechanics, the probabilistic strength function of a fiber composite is formulated to include the fiber strength statistics. The strong anisotropy in composite strength requires the statistical strength theory of fiber composites be developed for a composite production riser (CPR) subjected to general multiaxial loading. A probabilistic failure model, based on progressive damage and failure composite plies, has been constructed for CPR's with hybrid composite construction. An efficient computational procedure has been established, using a coupled nonlinear composite laminate shell stress analysis and the probabilistic failure model developed, for conducting rigorous CPR reliability assessment. Numerical solutions have been obtained for the CPRs designed and constructed for a TLP in 3,000 ft water subjected to the environmental loading specified in the NIST ATP Composite Production Riser Project. The results show that the CPR reliability is strongly governed by the statistical strength distribution functions of constituent load-bearing fibers and also by matrix cracking characteristics in the hybrid CPR system.
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