3 Scantlings

3.1 Superstructures sides and decks

3.1.1 Exposed sides and exposed deck plating

Exposed sides and exposed deck plating inclusive their supporting structure are to comply with the requirements given in [3.2.1] to [3.2.5] and bow impact requirements in Ch 10, Sec 1, [3.3], if applicable.

3.1.2 Deck plating of unexposed decks

The deck plating and supporting structures of unexposed decks of superstructures are to comply with requirements given in [3.2.2] to [3.2.5].

3.2 Deckhouses

3.2.1 Plating

The gross thickness of the plating, t_gr-exp, in mm, is not to be less than

where:

s_std : Standard reference spacing of stiffeners or beams, in mm, taken as:

s_std = 470 + 1.67 L₁

Where deck is protected by sheathing, the gross thickness of the deck plating may be reduced by 1.5 mm, without being less than 5 mm.

Where sheathing other than wood is used, attention is to be paid that the sheathing does not affect the steel. The sheathing is to be effectively fitted to the deck.

3.2.2 Deck plating of unexposed decks

The gross thickness of the unexposed deck plating, t_gr-unexp, in mm, is not to be less than the greater value of:

at the tier considered, and

but not less than 5.5 mm

3.2.3 Beams and stiffeners

The gross section modulus Z_gr, in cm³, and the gross shear area A_gr-sh, in cm², of transverse beams and of stiffeners are not to be less than:

3.2.4 Girders and transverses

The gross section modulus Z_gr, in cm³, and the gross shear area A_gr-sh, in cm², of girders and transverses are not to be less than:

Z_gr = c k P S ℓ_bdg ²

A_gr–sh = 0.05 k P S ℓ_shr

The girder depth is not to be less than ℓ/25. The web depth of girders scalloped for continuous deck beams is to be at least 1.5 times the depth of the deck beams.

3.2.5 Alternative grillage analysis for girders and transverses

Where arrangements of deck girders and transverses are such that these members act as a grillage structure, additional analysis may be carried out with a structural model based on the gross scantling.

The resulting stresses are not to exceed the following permissible bending, shear and equivalent stresses, in N/mm², taken as:

σ_b = 150 ⁄ k

τ = 100 ⁄ k

σ_σeqv = 180 ⁄ k

3.3 Deckhouse walls and end bulkheads of superstructure

3.3.1 Application

The requirements in [3.3] apply to end bulkhead of superstructure and deckhouse walls forming the only protection for openings and for accommodations.

Special consideration may be given to the bulkhead scantlings of deckhouses which do not protect openings in the freeboard deck, superstructure deck or in the top of a lowest tier deckhouse. Special consideration may also be given to the bulkhead scantlings of deckhouses which do not protect machinery casings, provided they do not contain accommodation or do not protect equipment essential to the operation of the ship.

3.3.2 Plate thickness

The gross thickness of the plating t_gr, in mm, is not to be less than the greater of:

for the lowest tier.

for the upper tiers, without being less than 5.0 mm.

3.3.3 Stiffeners

The gross section modulus Z_gr, in cm³, of the stiffeners is not to be less than:

This requirement assumes the webs of lowest tier stiffeners to be efficiently welded to the decks. Scantlings for other types of end connections are to be specially considered.

The section modulus of deckhouse side stiffeners needs not to be greater than that of side frames on the deck situated directly below, taking account of spacing s and span ℓ.

3.4 Companionways

3.4.1

The scantlings of companionways are to be determined in accordance with [3.2] and [3.3].