GUIDELINES FOR MARINE LIFTING & LOWERING OPERATIONS 0027/ND Rev 11 Page 40 of 84 11 STRUCTURAL CALCULATIONS 11.1 CODES AND SPECIFICATIONS 11.1.1
For analysis of the structure to be lifted and the lift points, a recognised and applicable offshore
structural design code shall be used as described in Section 11.7.
11.1.2
Adequate specifications for material properties, construction, welding, casting, inspection and testing
shall be used.
11.2 LOAD CASES AND STRUCTURAL MODELLING 11.2.1
Structural calculations, based on the load factors discussed above in Sections 5 and 6, shall include
adequate load cases to justify the structure. For example, for an indeterminate, 4-point lift the
following load cases should normally be considered:
a.
Base case, using gross or NTE weight, resolved to the lift points, but with no skew load factor.
b.
Gross or NTE weight, with skew load factor applied to one diagonal.
c.
Gross or NTE weight, with skew load factor applied to the other diagonal.
11.2.2
In all cases the loading shall be applied at the correct or minimum sling angle and point of action,
accounting for any offset. The effects of torsional loading imposed by the slings shall be considered.
11.3 STRUCTURE 11.3.1
The overall structure shall be analysed for the loadings shown in Section 11.2.
11.3.2
The primary supporting members shall be analysed using the most severe loading resulting from
Section 11.2, with a consequence factor applied (see Section 11.4)
11.4 CONSEQUENCE FACTORS 11.4.1
The following consequence factors,
c
, shall be further applied to the structure including lift points and
the lateral load effects on lift points, and their attachments into the structure:
