A finite element model to determine the socket strains and resin pressures in a resin socket termination for a wire rope has been developed. This model takes account of the relative movement between the socket and the resin cone that occurs when a termination is under load. To verify the accuracy of the model, computed socket strains were compared with strain measurements both on a full-scale termination and on a laboratory-scale model. As a result of these comparisons, modifications were made to the finite element model to improve its accuracy. It was concluded that the wires were held in the socket by frictional forces which were effective only in the resin section between 10 and 50 per cent of the socket basket length (measured from the front of the socket). This conclusion was verified by further laboratory tests.It was therefore deduced that manufacturing defects in the back half of the socket would not reduce the strength of the termination, while defects in the front half are much more significant. This was also demonstrated by laboratory tests for both quasi-static and fatigue loading. These conclusions apply only to sockets of the type described in this paper and are not necessarily true for all socket designs.

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Previously the authors have presented both theoretical and experimental work discussing the operating mechanism of a wire rope held in a tapered socket by means of a cast resin cone. The work reported here extends the investigation to address the question of whether the same socket fabricated with white metal operates in the same manner. To date, previous investigations have compared the operational efficiency of resin and white metal in terms of both strength and/or fatigue endurance. Some other work has analysed the operation of resin sockets or specific cast metal terminations. This paper seeks to draw the results from this work together, and, in addition to a theoretical analysis, presents experimental data obtained from a direct comparison of the operation mechanism for the same sockets filled with resin or white metal. Results show that white metal terminations have a very different distribution of stresses along the length of the socket basket from resin terminations, and a smaller but still significant amount of socket draw. For both types of termination the socket draw develops high frictional gripping forces which can transfer the load from the rope to the socket. The different stress distributions mean that the consequences of termination fabrication defects may not be the same for resin and white metal terminations.

A full characterisation of the individual components of a sea-state is key to enabling the response of an offshore structure to be accurately calculated. This paper discusses the partitioning of a time series of directional wave spectra into wind-sea and swell components with distinct frequency and direction characteristics. Once the wave data have been partitioned, JONSWAP or Pierson-Moskowitz parameters can be fitted to each spectrum using ‘best-fit’ techniques. The result of the partitioning and fitting analyses is a time series of wave parameters defining the wave spectrum for each component of the sea state. A 10-year site specific time series of directional wave spectra has been partitioned in this way and used in the analysis of the Triton FPSO, a turret moored FPSO in the central North Sea. The representation of the directionality and magnitude of each environmental force acting simultaneously on the vessel, allows the relative heading of the vessel to be determined and the mooring and hydrodynamic analyses to be performed. These analyses provided input to a structural analysis of the FPSO, which resulted in an inspection plan for monitoring the effects of the metocean conditions on the unit.