Section 2 Design heads
2.1 General
2.1.1 This Section contains the local design heads and pressures to be used in
the derivation of scantlings for decks, and bulkheads. Where scantlings in excess of
Rule requirements are fitted the procedure to be adopted to determine the permissible
head/pressure is also given.
2.2 Symbols
2.2.1 The symbols used in this Section are defined as follows:
L and D as defined in Pt 4, Ch 1, 5 Definitions
![](svgobject/03A4-40B0-BCBB-75E6311B74AD.xml_d4630896e79.png) |
= |
appropriate design head, in metres |
p |
= |
design loading, in kN/m2 (tonne-f/m2) |
![](svgobject/03A4-40B0-BCBB-75E6311B74AD.xml_d4630896e141.png) |
= |
applied loading, in kN/m2 (tonne-f/m3) |
E |
= |
correction factor for height of platform |
= |
– 0,15, but not less than zero
nor more than
0,147
|
2.3 Stowage rate and design heads
2.3.1 The following standard stowage rates are to be used:
- 1,39 m3/tonne for weather or general loading on decks.
- 0,975 m3/tonne for tanks with liquid of density 1,025
tonne/m3 or less on tank bulkheads and for watertight bulkheads.
For liquid of density greater than 1,025 tonne/m3, the corresponding
stowage rates are to be adopted.
2.3.2 The design heads and permissible deck loading are shown in Pt 4, Ch 6, 2.3 Stowage rate and design heads 2.3.2. For helicopter landing areas, see
Pt 4, Ch 6, 5 Helicopter landing areas.
Table 6.2.1 Design heads and permissible
deck loadings (SI units)
Structural item and position
|
Component
|
Standard stowage rate C, in m3/tonne
|
Design loading p ,in kN/m2
|
Equivalent design head in metres
|
Permissible deck loading in kN-/m2
|
Equivalent permissible head, in metres
|
1. Weather decks
|
—
|
—
|
—
|
|
—
|
—
|
(a)
Loading for minimum scantlings
|
(i) Exposed
deck
|
All
structure
|
1,39
|
9,0 + 14,41E
|
1,28 + 2,04E
|
9,0
|
1,28
|
(b)
Specified deck loading
|
(i) Exposed
deck
|
All
structure
|
1,39
|
+ 14,41E but not less than (a) above
|
0,14 + 2,04E
|
|
0,14
|
2. Other decks
|
(a)
Loading for minimum scantlings
|
(i) Work
areas
|
All structure
|
1,39
|
9,0
|
|
—
|
—
|
1,28
|
(ii) Storage
areas
|
All structure
|
1,39
|
14,13
|
|
—
|
—
|
2,0
|
(iii) Decks forming
crown of deep tanks
|
All structure
|
C
|
|
(see Note 2)
|
|
(see Note 2)
|
—
|
—
|
h
|
(iv) Accommodation
decks
|
All structure
|
1,39
|
8,5
|
|
—
|
—
|
1,2
|
(b)
Specified deck loading
|
(i) All areas
|
All structure
|
1,39
|
+ 14,41E but not less than (a) above
|
|
—
|
—
|
0,14
|
(c) Superstructure decks
(see Note 3
|
|
|
|
|
|
|
(i) 1st tier
|
All structure
|
—
|
—
|
0,9
|
(see Note 4)
|
—
|
—
|
(ii) 2nd tier
|
0,6
|
(iii) 3rd tier and above
|
0,45
|
(d) Walkways and access areas
|
All structure
|
1,39
|
4,5
|
|
—
|
—
|
0,64
|
3. Watertight bulkheads
|
All
structure
|
0,975
|
10,07
|
|
see
Pt 4, Ch 6, 7.3 Watertight and deep tank bulkheads 7.3.4
|
—
|
—
|
4. Deep tank bulkheads
|
All
structure
|
C but ≤ 0,975
|
|
|
see
Pt 4, Ch 6, 7.3 Watertight and deep tank bulkheads 7.3.4
|
—
|
—
|
NOTES
|
1.
The equivalent design head is to be used in conjunction with the
appropriate formulae in the Rules.
|
2.
Where h equals half the distance to the top of the overflow above
crown of tank.
|
3.
For forecastle decks forward of 0,12L from F.P., see
weather decks.
|
4.
Where the deck is exposed to the weather add 2,04E to the design
head.
|
Table 6.2.2 Design heads and permissible
deck loadings (metric units)
Structural item and position
|
Component
|
Standard stowage rate C, in m3/tonne
|
Design loading p ,in tonne
—f/m2
|
Equivalent design head in metres
|
Permissible deck loading in tonne-f/m2
|
Equivalent permissible head, in metres
|
1. Weather decks
|
—
|
—
|
—
|
|
—
|
—
|
(a)
Loading for minimum scantlings
|
(i) Exposed
deck
|
All
structure
|
1,39
|
0,92 + 1,467E
|
1,28 + 2,04E
|
0,92
|
1,28
|
(b)
Specified deck loading
|
(i) Exposed
deck
|
All
structure
|
1,39
|
+ 1,467E but not less than (a) above
|
1,4 + 2,04E
|
|
1,4
|
2. Other decks
|
(a)
Loading for minimum scantlings
|
(i) Work
areas
|
All structure
|
1,39
|
0,92
|
|
—
|
—
|
1,28
|
(ii) Storage
areas
|
All structure
|
1,39
|
1,44
|
|
—
|
—
|
2,0
|
(iii) Decks forming
crown of deep tanks
|
All structure
|
C
|
|
(see Note 2)
|
|
(see Note 2)
|
—
|
—
|
h
|
(iv) Accommodation
decks
|
All structure
|
1,39
|
0,865
|
|
—
|
—
|
1,2
|
(b)
Specified deck loading
|
(i) All areas
|
All structure
|
1,39
|
+ 1,467E but not less than (a) above
|
|
—
|
—
|
0,14
|
(c) Superstructure decks
(see Note 3
|
|
|
|
|
|
|
(i) 1st tier
|
All structure
|
—
|
—
|
0,9
|
(see Note 4)
|
—
|
—
|
(ii) 2nd tier
|
0,6
|
(iii) 3rd tier and above
|
0,45
|
(d) Walkways and
access areas
|
All structure
|
1,39
|
0,46
|
|
—
|
—
|
0,64
|
3. Watertight bulkheads
|
All structure
|
0,975
|
|
|
see
Pt 4, Ch 6, 7.3 Watertight and deep tank bulkheads 7.3.4
|
—
|
—
|
0,975
|
4. Deep tank bulkheads
|
All
structure
|
C but ≤ 0,975
|
|
|
see
Pt 4, Ch 6, 7.3 Watertight and deep tank bulkheads 7.3.4
|
—
|
—
|
NOTES
|
1.
The equivalent design head is to be used in conjunction with the
appropriate formulae in the Rules.
|
2.
Where h equals half the distance to the top of the overflow above
crown of tank.
|
3.
For forecastle decks forward of 0,12L from F.P., see
weather decks.
|
4.
Where the deck is exposed to the weather add 2,04E to the design
head.
|
|