Section
6 Other local loads
6.1 General
6.1.1 This
section gives formulations for design pressure loads for shell closing
appliances and requirements for gravity and inertial loads due to
equipment, payload, cargo, etc. acting on ramps and lifting appliances.
6.2 Loads for ramps and lifts, P
ra
6.2.1 The
loads acting on ramps and lifts intended to be used at sea, P
ra, is to be derived as follows:
|
P
ra
|
= |
W
cd (1 + f
d (a
z + a
ra)) kN/m2
|
where
|
W
cd
|
= |
is the
equivalent static pressure exerted by the cargo on the ramp or lift
as specified by the designer in kN/m2.
|
|
f
d
|
= |
duty factor for the lift or ramp |
| = |
2,0 for operation with personnel |
| = |
1,5 otherwise. |
6.2.2 If the
hoisting speed of the ramp or lift is such that the acceleration of
the lift will cause an increase in the forces acting on the lift,
then this acceleration term should be included.
6.2.3 Where
the lift or ramp is designed to operate totally or partially under
water, then due consideration is to be taken of the additional forces
applied to the lift or ramp as a direct consequence of the water environment,
e.g. added mass and velocity dependent damping forces.
6.3 Loads for windows and side scuttles in
deckhouses and superstructures, Pwi
6.3.1 The design pressure, P
wi, for windows and side scuttles in deckhouses and superstructures is to be
taken as:
In no case is the design pressure to be taken less than Pwi,min
as given by:
|
P
wi,min
|
= |
W
1 (10 + 0,04L
R)
kN/m2
|
Where Pwi,min need not be taken as greater than 15 kN/m2 for
the third tier of deckhouses or superstructures and above.
where
P
s is to be taken at the height of the deck below the window or side scuttle,
see 3.2
C
1 is defined in Vol 1, Pt 5, Ch 3, 5.5 Loads for deckhouses, bulwarks and superstructures, Pdh 5.5.1.
6.4 Loads for masts
6.4.1 The
inertia forces resulting from the motions of the ship are to be calculated
in accordance with Vol 1, Pt 5, Ch 3, 2 Motion response and
combined with the wind force defined below acting in the most onerous
direction for the case being considered.
6.4.2 Where
applicable the additional inertia forces due to ice accretion are
to be derived in accordance with Vol 1, Pt 5, Ch 2, 4.6 Ice accretion and included in the calculations.
6.4.3 The
wind pressure, p, acting on the structure is given by:
|
p
|
= |
 kN/m2
|
where
|
V
|
= |
wind
speed, in m/s. To be taken as 63 m/s unless otherwise specified. |
6.4.4 The
wind force, F
w, on the mast structure is given
by:
where
|
A
|
= |
the
effective area of the structure concerned, i.e. the solid area projected
on to a plane perpendicular to the wind direction, in m2
|
|
p
|
= |
wind pressure, in kN/m2
|
|
C
f
|
= |
force coefficient in the direction of the wind, as defined in Table 3.6.1 Force coefficient (Cf) .
|
Table 3.6.1 Force coefficient (Cf)
| Type
|
Description
|
Aerodynamic slenderness l/b or l/D
|
| 5
|
10
|
20
|
30
|
40
|
50
|
| Individual
members
|
Rolled
sections, rectangles, hollow sections, fIat plates, box sections with b or d
less than 0,5 m
|
1,30
|
1,35
|
1,60
|
1,65
|
1,70
|
1,80
|
| Circular sections, where
|
DV
s < 6 m2/s
|
0,75
|
0,80
|
0,90
|
0,95
|
1,00
|
1,10
|
|
|
DV
s ≥ 6 m2/s
|
0,60
|
0,65
|
0,70
|
0,70
|
0,75
|
0,80
|
|
|
b/d
|
|
|
|
|
|
|
| Box
sections with b or d greater than 0,5 m
|
≥2,00
|
1,55
|
1,75
|
1,95
|
2,10
|
2,20
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1,00
|
1,40
|
1,55
|
1,75
|
1,85
|
1,90
|
|
|
|
|
0,50
|
1,00
|
1,20
|
1,30
|
1,35
|
1,40
|
|
|
|
|
0,25
|
0,80
|
0,90
|
0,90
|
1,00
|
1,00
|
| Single lattice
frames
|
Flat sided
sections
|
1,70
|
| Circular sections, where
|
DV
s < 6 m2/s
|
1,20
|
|
|
DV
s ≥ 6 m2/s
|
0,80
|
| Plated structure
|
Plated structures on
ground or solid base
(air flow beneath structure
prevented)
|
1,10
|
| Symbols
|
|
l
|
= |
height of mast, in metres |
|
D
|
= |
diameter of mast, in metres |
|
V
s
|
= |
wind speed, in m/s |
|
b
|
= |
breadth of box section, in metres |
|
d
|
= |
depth of box section, in metres |
|
6.5 Hangar doors and other large doors in superstructures
6.5.1 The design pressure, Pds, for large doors in
superstructures is to be taken as:
where
Ps is to be taken at the height of the deck on which
the doors sits, see
Vol 1, Pt 5, Ch 3, 3.2 Combined hydrostatic and hydrodynamic pressure on the shell plating, Ps
C1 is defined in Vol 1, Pt 5, Ch 3, 5.5 Loads for deckhouses, bulwarks and superstructures, Pdh 5.5.1.
|