2 Criteria

2.1 General

2.1.1 Criteria are prescribed in the Rules to check the relevant limit states for the various structural elements. The strength assessments included in the Rules are defined in terms of yield check, buckling check, ultimate strength check, and fatigue check as indicated in Table 2.

Table 2 : Structural assessment

Structural Elements ⁽¹⁾		Yielding check	Buckling check	Ultimate strength check	Fatigue check
Local Structures	Stiffeners	Y	Y	Y ⁽²⁾	Y
Local Structures	Plating	Y	Y	Y ⁽³⁾	-
Primary supporting members		Y	Y	Y ⁽²⁾	Y
Hull girder		Y	Y ⁽⁴⁾	Y	-
(1) “Y” indicates that the structural assessment is to be carried out.
(2) The ultimate strength check is included in the buckling check.
(3) The ultimate strength check of plating is included in the yielding check formula of plating.
(4) The buckling check of stiffeners and plating taking part in hull girder strength is performed against stress due to hull girder bending moment and hull girder shear force.

2.2 Serviceability limit states

2.2.1 Hull girder

For the yielding check of the hull girder, the stress corresponds to a load at 10^-8 probability level.

2.2.2 Plating

For the yielding check and buckling check of platings constituting a primary supporting member, the stress corresponds to a load at 10^-8 probability level.

2.2.3 Stiffeners

For the yielding check of stiffeners, the stress corresponds to a load at 10^-8 probability level. Plating For the yielding check and buckling check of platings constituting a primary supporting member, the stress corresponds to a load at 10^-8 probability level.

2.2.3 Stiffeners

For the yielding check of stiffeners, the stress corresponds to a load at 10^-8 probability level.

2.3 Ultimate limit states

2.3.1 Hull girder

The ultimate strength of the hull girder is to be checked against the hull girder loads at 10^-8 probability level, amplified with the partial safety factor.

2.3.2 Plating

The ultimate strength of the plating between stiffeners and primary supporting members is to be checked against the loads at 10^-8 probability level.

2.3.3 Stiffeners

The ultimate strength of stiffeners is to be checked against the loads at 10^-8 probability level.

2.4 Fatigue limit state

2.4.1 Structural details

The fatigue life of representative welded structural details such as connections of stiffeners and primary supporting members and free edge of bulk carrier deck plating in way of hatch corner is to be assessed from long term distribution loads based on loads at 10^-2 probability level including the whipping-springing effects.

2.5 Accidental limit state

2.5.1 Hull girder

For bulk carriers, the yielding and ultimate strength of the hull girder in cargo hold flooded condition and in the damaged condition is to be assessed in accordance with Ch 5, Sec 1 and Ch 5, Sec 2.

The residual strength of oil tankers and bulk carriers is to be assessed according to Ch 5, Sec 3, for damages resulting from collision or grounding.

2.5.2 Double bottom structure

For bulk carriers, the double bottom structure in cargo hold flooded condition is to be assessed in accordance with Pt 2, Ch 1, Sec 3.

2.5.3 Bulkhead structure

For bulk carriers, the bulkhead structure in cargo hold flooded condition is to be assessed in accordance with Pt 2, Ch 1, Sec 3 and Pt 2, Ch 1, Sec 4.

2.5.4 Plating, stiffeners and PSM

The plating, stiffeners and PSM are to be assessed in flooded conditions in accordance with Ch 6 for yielding criteria and with Ch 8, Sec 3 for buckling criteria.