3.1.1 Where
an aluminium alloy complying with Ch 8 Aluminium Alloys of
the Rules for Materials (Part 2) is used in the construction of erections,
the scantlings of these erections are to be increased (relative to
those required for steel construction) by the percentages given in Table 8.3.1 Percentage increase of
scantlings.
Table 8.3.1 Percentage increase of
scantlings
| Item
|
Percentage increase
|
| Fronts, sides, aft
ends, unsheathed deck plating
|
20
|
| Decks sheathed in
accordance with Pt 3, Ch 8, 2.3 Deck plating 2.3.3
|
10
|
| Deck sheathed with
wood, and on which the plating is fixed to the wood sheathing at the centre
of each beam space
|
Nil
|
| Stiffeners and
beams
|
70
|
| Scantlings of small
isolated houses
|
Nil
|
3.1.2 The
thickness, t, of aluminium alloy members is to be not
less than:
|
t
|
= |
2,5
+ 0,022d
w mm but need not exceed 10 mm
|
where
|
d
w
|
= |
depth of the section, in mm. |
3.1.3 The minimum moment of inertia, 
I, of aluminium alloy stiffening members is to be not less than:
 |
= |
5,25Z
 e cm4
|
Where le is the effective length of the member in metres,
as defined in Pt 3, Ch 8, 1.2 Symbols 1.2.1, and Z is the section modulus of the stiffener
and attached plating calculated using the formulae in Pt 3, Ch 8, 2.2 Stiffeners and their connections 2.2.1 and Pt 3, Ch 8, 2.4 Deck longitudinals and beams 2.4.3, as applicable, taking k as 1.