Clasification Society Rulefinder 2020 - Version 9.33 - Fix
Common Structural Rules - Common Structural Rules for Bulk Carriers and Oil Tankers, January 2019 - Part 1 General Hull Requirements - Chapter 5 Hull Girder Strength - Section 3 Hull Girder Residual Strength - 2 Checking Criteria

2 Checking Criteria

2.1 General

2.1.1 The vertical hull girder ultimate bending capacity in the damaged condition is to be checked for the damage conditions specified in [2.2] in hogging and sagging conditions. For the damage conditions specified in [2.2], for the design load scenario A, as defined in Table 1:

Table 1 : Design load scenarios

Design load scenario Permissible still water bending moment in damage, Msw-D
Collision A: S+D Msw-h or Msw-s
Grounding A: S+D Msw-h or Msw-s

2.1.2 The vertical hull girder ultimate bending capacity in the damaged condition at any hull transverse section is to satisfy the following criteria:

where:

MD : Vertical bending moment in the damaged condition, in kNm, to be obtained as specified in [2.3].

MUD : Vertical hull girder ultimate bending capacity in the damaged condition, in kNm, to be obtained as specified in [2.4].

γRD : Partial safety factor for the vertical hull girder ultimate bending capacity in the damaged condition, to be taken equal to:
  • γRD = 1.0
CNA : Neutral axis coefficient taken as:
  • CNA = 1.0 for grounding,
  • CNA = 1.1 for collision.

2.2 Damage conditions

2.2.1 General

The damage conditions specified for collision in [2.2.2] and for grounding in [2.2.3] are to be considered. The damage extents specified in [2.2.2] and [2.2.3] are to be measured from the moulded lines of the ship.

Stiffener element is to be considered intact unless the connection of stiffener with attached plate is included in the damaged extent.

Plates and stiffeners of inner bottom and inner hull longitudinal bulkhead are to be considered intact unless the damage extent exceeds the moulded distance from inner bottom and inner hull longitudinal bulkhead plate respectively, to the hull envelope plate.

2.2.2 Collision

For the collision assessment of the considered transverse damage cross section, the damage is to be considered on one side and inclusive of the freeboard deck.

The damage for collision extends from the point of intersection of the moulded lines of deck and side:
  • vertically downward for a distance h and upward without limit,
  • transversally inboard for a distance d and outward without limit,

where h and d are given in Table 2 according to the side shell arrangement in the considered damage transverse section.

On ships with a rounded gunwale, the point of intersection is to be taken from the continuation of the moulded lines of deck and side.

Table 2 : Damage extent for collision

Damage penetration, in m

 Side shell arrangement
Single side Double side
Height,h 0.75D 0.60D
Depth,d B/16 B/16

Figure 1 : Damage extent for collision

The capacity of the damaged transverse cross section is calculated with the damage extent on one side, the ship kept in upright position.

2.2.3 Grounding

For the grounding assessment of the considered transverse damage cross section, the damage is to be considered on the bottom in the most unfavourable transversal position as regard to the structure considered by the damage.

The damage extent for grounding is given in Table 3.

Table 3 : Damage extent for grounding

Damage penetration, in m Bulk carriers Oil tankers
Height,h Min (B /20, 2) Min (B /15, 2)
Breadth,b 0.60 B 0.60 B

Figure 2 : Damage extent for grounding

2.3 Hull girder ultimate bending loads in the damaged condition

2.3.1 The vertical bending moment, MD in hogging and sagging conditions, to be considered in the ultimate strength check of the hull girder in the damaged condition, is to be obtained from the following formula:

MD = γSD Msw–D + γWD Mwv

Msw-D : Permissible still water bending moment, in kNm, in hogging and sagging conditions at the hull transverse section considered, as defined in Table 1.

Mwv : Vertical wave bending moment, in kNm, in hogging and sagging conditions at the hull transverse section considered, as defined in Ch 4, Sec 4, [3.1].

γSD : Partial safety factor for the still water bending moment in the damaged condition, to be taken equal to:
  • γSD = 1.1
γWD : Partial safety factor for the vertical wave bending moment in the damaged condition, to be taken equal to:
  • γWD = 0.67

2.4 Hull girder ultimate bending capacity in the damaged condition

2.4.1 The hull girder ultimate bending capacity in the damaged condition is to be calculated according to Ch 5, App 2, with the damaged parts assumed not to contribute to the hull girder strength. When assessing the ultimate bending capacity, MUD of the damaged hull sections, damaged area as defined in [2.2] carries no loads and is to be removed in the capacity model.

2.4.2 The effective area of the intact parts for the hull girder ultimate strength capacity assessment is specified in Ch 5, App 2.

Parent topic: Section 3 Hull Girder Residual Strength
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