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214 Part 11 Ultimate Strength
11.1.2 Buckling Failure Modes
The characteristic geometric parameters of a stiffened cylindrical shell are defined in Figure
11.2.
Figure 11.2 Geometrical Parameters of a Stiffened Cylindrical Shell
The boundary conditions are assumed simply supported and constrained. The design loads are:
Compressive stress due to longitudinal force and bending moment
0
External overpressure
Combined compressive stress and external pressure
Major factors affecting strength of cylindrical shells include:
Residual stresses and geometrical imperfections
Dents
Corrosion defects
The effects of residual stresses and geometric imperfections have been implicitly accounted
for in the criteria discussed in this Chapter. However, if the fabrication tolerance is violated, or
dents and significant corrosion defects are found in in-service structures, repair and additional
strength analysis are necessary. For pressure vessels, pipelines and risers, criteria for
pressurized cylinders under combined extemalhntemal pressure, axial force and bending are
given in Bai (2001), among other references.
