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Buckling/CoIIapse of Deepwater Metallic Pipes 49
3.4 Pipes under Pressure Axial Force and Bending
Bucklingkollapse of pipes under internal pressure, axial force and bending accounting for
yield anisotropy.
In this section an analytical solution is given for the calculation of the moment capacity for a
pipe under combined internal pressure, axial force and bending, with a corrosion defect
symmetrical to the bending plan. The moment capacity of the pipe is here defined as the
moment at which the entire cross section yields.
The solution presented in this section takes the following configurations into account:
Corroded area in compression (case 1), in compression and some in tension (case 2), in
tension (case 3), in tension and some in compression (case 4). The four cases are shown in
Figure 3.4.
The analytical solution for the moment capacity for the four cases are presented in the
following, but only case 1 is fully discussed here.
I Plane of bending , Plsne of bending
neutral axis
I Plane of bending I Plane of bending
neutral axis
Figure 3.4 The four cases of defects and loads.
3.4.1 Case 1 - Corroded Area in Compression
To keep the complexity of the equations on a reasonable level, the following assumptions
have been made:
