2.1 Thickness of bulkhead and side plating
2.1.1 The thickness, t, of plating of the fronts, sides and aft ends of all erections, other than the sides of superstruc- tures where these are an extension of the side shell, is to be not less than:
t = 0,003s kh mm
but in no case is the thickness to be less than: (a) for the lowest tier:
t =
(
5,0 + 0,01L3)
k mm(b) for the upper tiers:
t = 4,0 + 0,01L3 k mm but not less than 5,0 mm. 2.1.2 The thickness of sides of poops and bridges is to be as required by Ch 6,3 or Pt 4, Ch 1,5, as appropriate.
2.2 Stiffeners and their connections
2.2.1 The modulus of stiffeners, Z, on front, side and end bulkheads of all erections, other than sides of superstructures, is to be not less than:
Z = 0,0035h s ls2 k cm3
2.2.2 The section modulus of side frames of poops and bridges is to comply with the requirements of Ch 6,4 or Pt 4, Ch 1,6, as appropriate.
2.2.3 The end connections of stiffeners are to be as given in Table 8.2.1.
2.3 Deck plating
2.3.1 The thickness of erection deck plating is to be not less than that required by Table 8.2.2.
2.3.2 When decks are fitted with approved sheathing, the thicknesses derived from Table 8.2.2 may be reduced by 10 per cent for a 50 mm sheathing thickness, or five per cent for 25,5 mm, with intermediate values in proportion. The steel deck is to be coated with a suitable material in order to prevent corrosive action, and the sheathing or composition is to be effectively secured to the deck, see also Pt 6, Ch 4. Inside deckhouses the thickness may be reduced by a further 10 per cent.
RULES ANDREGULATIONS FOR THECLASSIFICATION OFSHIPS, July 2000
Superstructures, Deckhouses and Bulwarks
Part 3, Chapter 8
Sections 1 & 2
LLOYD’SREGISTER OFSHIPPING
2
Position a
Lowest tier – unprotected front Second tier – unprotected front Third tier
and above – unprotected front All tiers – protected fronts All tiers – sides
All tiers – aft end where aft of amidships All tiers – aft end where
forward of amidships 2,0 + 0,0083L3 1,0 + 0,0083L3 0,5 + 0,001L3– 0,4 X L 0,7 + 0,001L3– 0,8 X L 0,5 + 0,0067L3 Table 8.1.1 Values of a
Length L l Expression for l
metres 20 0,89 30 1,76 40 2,57 50 3,34 60 4,07 70 4,76 80 5,41 90 6,03 110 7,16 130 8,18 150 9,10 150 9,10 170 9,65 190 10,08 210 10,43 230 10,69 250 10,86 270 10,98 290 11,03 300 11,03 300 and above 11,03 L £ 150 m L ³ 300 m lÿ= 11,03 150 m £ L £ 300 m Table 8.1.2 Values of l l =
(
e–)
–(
1 –( )
L 2)
150 L 300 L 10 l = e– L 300 L 102.4 Deck longitudinals and beams
2.4.1 The section modulus of superstructure deck longitu- dinals and beams is to be in accordance with the requirements for location (2) in Table 1.4.4 and location (3) in Table 1.4.5 in Pt 4, Ch 1, using design heads not less than those specified in Table 3.5.1 in Chapter 3 for superstructure decks.
Superstructures, Deckhouses and Bulwarks
Part 3, Chapter 8
Section 2
2.4.2 Transverse deck beams in deckhouses and deck longitudinals other than as in 2.7 are to have a section modulus, Z, not less than:
Z = 0,0048h2 s le2 k cm3, but in no case less than: Z = 0,025s cm3
and the value of h2, the load head, is to be taken as not less than:
on first tier decks 0,9 m
on second tier decks 0,6 m
on third tier decks and above 0,45 m.
2.5 Deck girders and transverses
2.5.1 The section modulus of deck girders and trans- verses is to be in accordance with the requirements for location (1) in Table 1.4.6 in Pt 4, Ch 1, using design heads not less than those specified in Table 3.5.1 in Chapter 3 for superstructure decks.
2.6 Strengthening at ends and sides of erections
2.6.1 Web frames or partial bulkheads are to be fitted within poops and bridges that have large deckhouses or other erections above.
2.6.2 Web frames or equivalent strengthening are also to be arranged to support the sides and ends of large deck- houses.
2.6.3 These web frames should be spaced about 9 m apart and are to be arranged, where practicable, in line with watertight bulkheads below. Webs are also to be arranged in way of large openings, boats davits and other points of high loading.
2.6.4 Arrangements are to be made to minimize the effect of discontinuities in erections. All openings cut in the sides are to be substantially framed and have well rounded corners. Continuous coamings or girders are to be fitted below and above doors and similar openings. House tops are to be strengthened in way of davits. Special care is to be taken to minimize the size and number of openings in the side bulk- heads in the region of the ends of erections within 0,5L amidships. Account is to be taken of the high vertical shear loading which can occur in these areas.
2.6.5 Adequate support under the ends of erections is to be provided in the form of webs, pillars, diaphragms or bulk- heads in conjunction with reinforced deck beams. At the corners of houses and in way of supporting structures, attention is to be given to the connection to the deck, and doublers or equivalent arrangements should generally be fitted.
2.6.6 The side plating of bridges having a length of 0,15L or greater is to be increased in thickness by 25 per cent at the ends of the structure, and is to be tapered into the upper deck sheerstrake. This plating is to be efficiently stiffened at the upper edge and supported by web plates not more than 1,5 m from the end bulkhead. Proposals for alternative arrange- ments, including the use of higher tensile steel, will be individually considered.
Position 1. Front stiffeners of lower
tiers and of upper tiers when L is 160 m or greater 2. Front stiffeners of upper
tiers when L is less than 160 m
3. Side stiffeners of lower tiers where two or more tiers are fitted
4. Side stiffeners if only one tier is fitted, and aft end stiffeners of after deck- houses on deck to which D is measured
5. Side stiffeners of upper tiers when L is 160 m or greater
6. Side stiffeners of upper tiers when L is less than 160 m
7. Aft end stiffeners except as covered by item 4 8. Exposed machinery and
pump-room casings – Front stiffeners on amid- ship casings and all stiffeners on aft end casings which are situated on the deck to which D is measured
9. All other stiffeners on exposed machinery and pump-room casings
Attachment at top and bottom
See Chapter 10
May be unattached
Bracketed, unless stiffener modulus is increased by 20 per cent and ends are welded to the deck all round
See Chapter 10 See Chapter 10 May be unattached May be unattached Bracketed 6,5 cm2of weld
Thickness of deck plating, in mm Position Top of first tier erection Top of second tier erection Top of third
tier and above
but not less than 5,0 mm L£ 100 m L > 100 m
Table 8.2.1 Stiffener end connections
Table 8.2.2 Thickness of deck plating
(5,5 + 0,02L) ks sb (5,0 + 0,02L) ks sb (4,5 + 0,02L) ks sb 6,5 ks sb 7,0 ks sb 7,5 ks sb
2.7 Erections contributing to hull strength
2.7.1 Where a long superstructure or deckhouse is fitted, extending within 0,5L amidships, the scantlings of the first tier deck plating and longitudinals may be required to be increased, see also Ch 3,3.4 and Ch 4,2.3.
2.8 Unusual designs
2.8.1 Where superstructures or deckhouses are of unusual design, the strength is to be not less than that required by this Chapter for a conventional design.