1 General

1.1 Scope

1.1.1 This section applies to plate panels including curved plate panels and stiffeners subject to hull girder compression and shear stresses. In addition the following structural members subject to compressive stresses are to be checked:

Corrugation of transverse vertically corrugated bulkhead.
Corrugation of longitudinal corrugated bulkhead.
Strut.
Pillar.
Cross tie.

1.1.2 The hull girder buckling strength requirements apply along the full length of the ship.

1.1.3 Design load sets

The buckling checks are to be performed for all design load sets defined in Ch 6, Sec 2, [2], both in intact and in flooded conditions with pressure combination defined in Ch 6, Sec 2, [1.3].

For each design load set, for all dynamic load cases, the lateral pressure is to be determined according to Ch 4 at the load calculation point defined in Ch 3, Sec 7, and is to be applied together with the hull girder stress combinations given in [2.2].

1.2 Equivalent plate panel

1.2.1 In longitudinal stiffening arrangement, when the plate thickness varies over the width b, of a plate panel, the buckling check is to be performed for an equivalent plate panel width, combined with the smaller plate thickness, t₁. The width of this equivalent plate panel, b_eq, in mm, is defined by the following formula:

where:

: Width of the part of the plate panel with the smaller net plate thickness, t₁, in mm, as defined in Figure 1.

: Width of the part of the plate panel with the greater net plate thickness, t₂, in mm, as defined in Figure 1.

Figure 1 : Plate thickness change over the width

1.2.2 In transverse stiffening arrangement, when an EPP is made with different thicknesses, the buckling check of the plate and stiffeners is to be made for each thickness considered constant on the EPP, the stresses and pressures being estimated for the EPP at the LCP.

1.2.3 Materials

When the plate panel is made of different materials, the minimum yield strength is to be used for the buckling assessment.