According to the API code [17], the following design conditions must be considered in the analysis of offshore structures:
(i) Design for in-place conditions, which will include resistance of the structure to gravity loads, wind–wave–current loads, ice loads, earthquake loads, and accidental (including impact) loads. The loads computed for the structure must consider the maximum loads likely to be exerted during the drilling, production, and work-over operations, singly or in combination. In addition, the fatigue resistance requirements of the structure also must be considered.
(ii) The structural analysis must also consider the loads that will be applied on the structure during its fabrication, transportation, and installation operations. If offshore structures are to be relocated to new sites, then loads resulting from the removal, site-loading onto barge, transportation, and installation should be considered.
(iii) The strength of stability check to be applied to the design of individual member must take into consideration the load factor to be applied according to Table 6.5; in addition, the resistance factor must also be applied to the nominal strength of each member.
(iv) Usually, a three-dimensional elastic structural analysis is found to be sufficient; but in the case of the jacket structure and the lateral pile–soil system, it may be necessary to carry out nonlinear pile–soil analysis to ensure load-displacement compatibility between the two components of the offshore structure.
(v) Careful consideration should be given to provide sufficient redundancy in the structure against failure based on the system reliability analysis.
(vi) Corrosion protection should be provided according to the governing specifications such as NACE RP-01-76 [17].
(vii) Finally, the analysis should also take into account the stresses and deformations induced by temperature variation, creep, relaxation, and uneven settlement.


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