Section 7 Direct calculation procedures
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Inland Waterways Ships, July 2022 - Part 4 Ship Structures (Ship Types) - Chapter 8 Tugs, Pusher Tugs and Launches - Section 7 Direct calculation procedures

Section 7 Direct calculation procedures

Parent topic: Chapter 8 Tugs, Pusher Tugs and Launches

7.1 General

7.1.1 This Section contains guidance for direct calculations and information regarding maximum permissible stresses for structural members in the deck and bottom.

7.1.2 Where direct calculation is adopted, all data in support of the calculation, i.e. support conditions and loads are to be submitted, together with the calculation.

7.2 Permissible stresses

7.2.1 For local structural members in bottom and deck, the maximum bending stresses, shear stresses and equivalent stresses are not to exceed the values given in Table 8.7.1 Maximum permissible stresses in local members in bottom and deck, in N/mm2.

Table 8.7.1 Maximum permissible stresses in local members in bottom and deck, in N/mm2

Item Bending stress,
σb 		Shear stress,
τ 		Equivalent stress,
σe

See Note

Bottom transverses,
bottom girders, deck girders, deck transverses 		0,52σo 0,35σo 0,75σo
Deck beams, floors,
deck longitudinals, bottom longitudinals 		0,58σo 0,35σo 0,80σo

Note The equivalent stress σe is to be calculated according to the formula

7.3 Design criteria for the bottom structure

7.3.1 The draught of the ship is to be taken as T + 0,4 m.

7.3.2 The horizontal and vertical loads on a protective structure as mentioned in Pt 4, Ch 8, 6.1 General 6.1.2 may be taken as the maximum weight of the ship.

7.4 Design criteria for the deck structure

7.4.1 For the assessment of the deck structure in way of the towing bitt, towing winch or towing hook, the pull in the towing wire used in the calculation is to be taken as 0,8 times the breaking strength of the towing wire, in conjunction with the permissible stresses given in Table 8.7.1 Maximum permissible stresses in local members in bottom and deck, in N/mm2.

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