General
1.1 Application
1.1.1 This Chapter applies to all types of ship covered by Part 4, except where specifically stated otherwise.
1.1.2 The requirements given are those specific to aft ends and relate to structure situated in the region aft of 0,3L from the after perpendicular.
1.1.3 Requirements for cargo space structure within this region not dealt with in this Chapter are to be as detailed in the relevant Chapter of Part 4 for the particular ship type.
1.2 Structural configuration
1.2.1 The Rules provide for both longitudinal and transverse framing systems.
1.2.2 In the case of container ships and open type ships additional requirements may apply as detailed in Pt 4, Ch 8.
1.3 Structural continuity
1.3.1 Suitable scarfing arrangements are to be made to ensure continuity of strength and the avoidance of abrupt structural changes.
1.3.2 Where longitudinal framing terminates and is replaced by a transverse system, adequate arrangements are to be made to avoid an abrupt changeover. Where a poop is fitted extending forward of 0,15L from the A.P., longitudinal framing at the upper deck and topsides is generally to be continued aft of the forward bulkhead of this superstructure. In bulk carriers and oil tankers the longitudinal framing at the upper deck is to be maintained over the cargo space region and continued over the aft end region.
1.3.3 In oil tankers with machinery aft, continuity of the longitudinal bulkheads is to be maintained as far as is practicable into the machinery space, and suitable taper brackets are to be fitted at their ends.
1.3.4 In bulk carriers with machinery aft, continuity of the topside tank and double bottom hopper tank structure is to be maintained over the cargo space region and as far as is practicable continued into the machinery space, and suitable taper brackets are to be arranged at their ends. Also a vertical taper bracket in line with the vertical strake of the topside tank is to be fitted at the forward side of the aft bulk- head of the cargo space region. Where the topside tank and double bottom hopper tank structures terminate at the cargo space aft bulkhead, the vertical strake of the topside tank is to be arranged with an integral taper bracket and continued through the bulkhead into the machinery space for a distance of 0,2B, and the ends of the hopper and topside structures are to be arranged with suitable taper brackets. In addition, in way of the cargo space aft bulkhead, a girder or intercostal bulb plate stiffeners (fitted between and connected to the bulkhead vertical stiffeners), are to be arranged on the aft side in line with the sloped bulkheads of the topside and hopper tanks clear of the taper brackets.
1.3.5 In container or similar ships having continuous side tanks or double skin construction in way of the cargo spaces, the longitudinal bulkheads are to be continued as far aft as is practicable and are to be suitably tapered at their ends. Where, due to the ship’s form, such bulkheads are stepped, suitable scarfing is to be arranged.
1.4 Symbols and definitions
1.4.1 The following symbols and definitions are applicable to this Chapter unless otherwise stated:
L, B, D, T as defined in Ch 1,6.1
kL, k = higher tensile steel factor as defined in Ch 2,1.2
l = overall length of stiffening member, in metres, see Ch 3,3.3
le = effective length of stiffening member, in metres, see
Ch 3,3.3
s = spacing of secondary stiffeners, in mm t = thickness of plating, in mm
S = spacing, or mean spacing, of primary members, in metres
Z = section modulus of stiffening member, in cm3, see
Ch 3,3.2
rÿ = relative density (specific gravity) of liquid carried in a tank and is to be taken not less than 1,025
I = inertia of stiffening member, in cm4, see Ch 3,3.2. 1.4.2 For the purpose of this Chapter the after perpen- dicular, A.P., is defined as the after limit of the Rule length L.
Part 3, Chapter 6
Section 1Section
1 General
2 Deck structure
3 Shell envelope plating
4 Shell envelope framing
5 Single and double bottom structure
6 After peak structure
Aft End Structure
■
Section 2
Deck structure
2.1 General
2.1.1 Where the upper deck is longitudinally framed outside the line of openings in the midship region, this system of framing is to be carried as far aft as possible, see also Pt 4, Ch 9,1.3.
2.2 Deck plating
2.2.1 The thickness of strength/weather deck plating is to comply with the requirements of Table 6.2.1.
2.2.2 The thickness of lower deck plating is to comply with the requirements of Table 6.2.2.
2.2.3 The taper thickness of the strength deck stringer plate is to be increased by 20 per cent at the ends of a poop or bridge where the end bulkhead is situated forward of 0,25L from the A.P. No increase is required where the end bulkhead lies aft of 0,2L from the A.P. The increase at intermediate positions is to be determined by interpolation.
2.2.4 The deck plating thickness and supporting struc- ture are to be suitably reinforced in way of deck machinery, and in way of cranes, masts or derrick posts.
2.2.5 Where long, wide hatchways are arranged at lower decks it may be necessary to increase the deck plating thick- ness to ensure effective support for side framing.
2.3 Deck stiffening
2.3.1 The scantlings of strength/weather deck longitudi- nals are to comply with the requirements of Table 6.2.3.
2.3.2 The scantlings of cargo and accommodation deck longitudinals are to comply with the requirements given in Table 1.4.4 in Pt 4, Ch 1.
2.3.3 End connections of longitudinals to bulkheads are to provide adequate fixity, lateral support and so far as prac- ticable, direct continuity of longitudinal strength.
2.3.4 The scantlings of weather deck beams are to comply with the midship requirements for the particular ship type.
2.3.5 The scantlings of lower deck beams are to comply with the requirements of Table 1.4.5 in Pt 4, Ch 1.
2.3.6 End connections of beams are to be in accordance with the requirements of Ch 10,3.
RULES ANDREGULATIONS FOR THECLASSIFICATION OFSHIPS, July 2000
Part 3, Chapter 6
Section 2LLOYD’SREGISTER OFSHIPPING
2
Table 6.2.1 Strength/weather deck plating aft (excluding poop deck)
Symbols Location Thickness, in mm
L, s, S, k, r as defined in 1.4.1
f = 1,1 – but is to be taken not greater than 1,0
h4 = tank head, in metres, as defined in Ch 3,5
sb = standard frame spacing as follows: Aft of 0,15L from the A.P.:
sb =
(
510 +)
mm or 850 mm, whichever is the lessers1 = s, but is to be taken not less than sb
L
0,6
s
2500S
(1) Aft of 0,075L from the A.P.
(2) Between 0,075L and 0,15L from the A.P.
(3) Forward of 0,15L from the A.P. (4) Inside poop extending forward of
0,15L
(5) In way of the crown of a tank
The greater of the following: (a) t = (5,5 + 0,02L)
(b) the taper thickness, see Notes 1, 2 and 3
(c) for oil tankers, the thickness is also to be in accordance with Pt 4, Ch 9,4.3.3 ks1 sb t = 0,004sf + 3,5 or (1) to (4) as applicable, whichever is the greater but not less than 7,5 mm where L³ 90 m, or 6,5 mm where L < 90 m
r k h4 1,025
The taper thickness, see Notes 1, 2 and 3, or as (2)(c) whichever is the greater As for a lower deck, see Note 4
NOTES
1. The taper thickness is to be determined from Table 3.2.1 in Chapter 3.
2. For taper area requirements, see Table 3.2.1 in Chapter 3. 3. For thickness of upper deck plating in way of the cargo tanks of
oil tankers or ore carriers, see also Pt 4, Ch 9, Ch 10 or Ch 11.
4. The exposed weather deck taper thickness is to extend into a poop or bridge for at least one-third of the breadth of the ship from the superstructure end bulkhead.
t = (5,5 + 0,02L) ks1 sb