Figure B.4 Midship section of ship with timber packages secured with
uprights
Ship particulars
| Length
between perpendiculars, LPP:
|
134 metres
|
| Moulded
breadth, BM:
|
22 metres
|
| Service
speed:
|
14.5 knots
|
| Metacentric height, GM:
|
0.7 metres
|
The deck cargo has the dimensions L x B x H = 80 x 19.7 x 2.4 metres. The
total weight of the deck cargo is taken as 1,600 tons.
With ship particulars as above and considering a stowage position on deck
low, Annex
13 of the CSS Code gives a transverse acceleration of at
= 5.3 m/s2
, using the following basic acceleration and correction factors:
|
at
basic
|
=
|
6.5 m/s2
|
=
|
Basic transverse acceleration
|
|
fR1
|
=
|
0.80
|
=
|
Correction factor for length and speed
|
|
fR
2
|
=
|
1.00
|
=
|
Correction factor for BM/GM
|
|
at
|
=
|
at basic
• fR1
• fR2
|
=
|
6.5 • 0.81 • 1.00 =
|
5.3 m/s
2
|
Cargo properties
| m
|
=
|
1,600 ton
|
=
|
Mass of
the section to be secured in tons, including absorbed water and possible
icing
|
| μinternal
|
=
|
0.30
|
=
|
Coefficient of internal friction between the timber packages
|
| H
|
=
|
2.4 m
|
=
|
Height
of deck cargo in metres
|
| b
|
=
|
1.1 m
|
=
|
Width of
each individual stack of packages
|
| np
|
=
|
18 pcs
|
=
|
Number
of stacks of timber packages abreast in each row
|
| q
|
=
|
2 pcs
|
=
|
Number of
layers of timber packages
|
| RS
|
|
3.5 kN/M
|
=
|
Racking
Strength per timber package in kN/
|
| N
|
=
|
36 pcs
|
=
|
Number of
uprights supporting the considered section on each side
|
| H
|
=
|
2.4 m
|
=
|
Height
above deck at which hoglashings are attached to the uprights in
metres
|
| K
|
=
|
1.8
|
=
|
Factor for considering hog lashings
|
|
|
|
k = 1 if no hog lashings are
used
|
|
|
|
k = 1.8 if hog lashings
are used
|
The design bending moment, taken as the maximum bending moment calculated
by the three formulae above multiplied with the safety factor of 1.35, thus becomes 106
kNm:
- M bending
≥
Suitable dimensions for uprights
With MSL taken as 50% of the MBL for steel with the ultimate strength 360
MPa (N/mm2), the required bending resistance, W, can be calculated as:
|
W
|
= |
|
| = |
|
| = |
589·103
mm3
|
| = |
589 cm3
|
Thus, uprights made from either HE220A profiles or a cylindrical profile
with an outer diameter of 324 mm and a wall thickness of 10.3 mm are suitable (see section
B.7).
Strength in hoglashings
The required MSL of each hog lashing is calculated by the following
formula:
In this case, the hoglashings are attached at a height of h = 3.5 m and the
required strength is calculated as:
MSL ≥
= 
= 15 kN ≈ 1.5 ton