Section
5 Design criteria and load combinations
5.1 Hull girder design criteria for mono-hull craft
5.1.1 The Rule
bending moment, M
R, and associated shear forces, Q
R, for non-displacement craft are to be determined
as follows:
-
The Rule bending
moment, M
R, is to be taken as the greater
of (M
w + M
S), as defined
in Pt 5, Ch 5, 2.2 Vertical wave bending moments and Pt 5, Ch 5, 2.3 Still water bending moments and M
DW, as defined in Pt 5, Ch 5, 2.6 Dynamic bending moments and associated shear forces, taking into account the hogging
and sagging conditions.
-
The Rule shear forces, Q
R, are to be taken as the greater of (Q
w + Q
S), as defined in Pt 5, Ch 5, 2.4 Wave shear force and Pt 5, Ch 5, 2.5 Still water shear force and Q
DW, as defined in Pt 5, Ch 5, 2.6 Dynamic bending moments and associated shear forces,
taking into account the hogging and sagging conditions.
5.1.2 The Rule
bending moment, M
R, and associated shear forces, Q
R, for displacement craft are taken to be the greater
of the following:
-
The Rule bending
moment, M
R, is to be taken as (M
w + M
S), as defined in Pt 5, Ch 5, 2.2 Vertical wave bending moments and Pt 5, Ch 5, 2.3 Still water bending moments ,
taking into account the hogging and sagging conditions.
-
The Rule shear forces, Q
R, are to be taken as (Q
w + Q
S), as defined in Pt 5, Ch 5, 2.4 Wave shear force and Pt 5, Ch 5, 2.5 Still water shear force , taking into account the hogging
and sagging conditions.
5.2 Hull girder design criteria for multi-hull craft
5.2.1 The Rule
bending moment, M
R, and associated shear forces, Q
R, for non-displacement craft are to be determined
as follows:
-
The Rule bending
moment, M
R, is to be taken as the greater
of M
MW, as defined in Pt 5, Ch 5, 3.2 Vertical wave bending moments and associated shear forces and M
MDW, as defined in Pt 5, Ch 5, 3.3 Dynamic bending moments, taking into account the hogging
and sagging conditions.
-
The Rule shear forces, Q
R, are to be taken as the greater of Q
MW, as defined in Pt 5, Ch 5, 3.2 Vertical wave bending moments and associated shear forces and Q
MDW, as defined in Pt 5, Ch 5, 3.3 Dynamic bending moments,
taking into account the hogging and sagging conditions.
5.2.2 The Rule
bending moment, M
R, and associated shear forces, Q
R, for displacement craft are taken to be the greater
of the following:
-
The Rule bending
moment, M
R, is to be taken as M
MW, as defined in Pt 5, Ch 5, 3.2 Vertical wave bending moments and associated shear forces, taking
into account the hogging and sagging conditions.
-
The Rule shear forces, Q
R, are to be taken as Q
MW,
as defined in Pt 5, Ch 5, 3.2 Vertical wave bending moments and associated shear forces, taking into
account the hogging and sagging conditions.
5.3 Primary load combinations applicable to the cross-deck structure
of multi-hull craft
5.3.1 If the
global load criteria given in this Chapter are utilised to check cross-deck
strength against ductile failure modes involving gross deformation,
the following load combinations are to be considered depending on
heading of the craft:
-
Head sea
0,1M
B + M
R +
0,1 M
T
-
Beam sea
M
B + 0,1 M
R +
0,2 M
T
-
Quartering sea
0,1M
B + 0,4 M
R + M
T
M
B, M
T and M
R are to be taken from Pt 5, Ch 5, 4.2 Global loads for multi-hull craft with partially submerged hulls 4.2.1, Pt 5, Ch 5, 4.2 Global loads for multi-hull craft with partially submerged hulls 4.2.3 and Pt 5, Ch 5, 5.2 Hull girder design criteria for multi-hull craft for
multi-hull craft with partially submerged hulls.
5.3.3 The strength
calculations are, in general, to be conducted using the finite element
analysis techniques with a three dimensional model.
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