Iranian Classification Society Rules
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Section 5 Platings
501. Allowable stresses
Maximum allowable
3.4.5.
bending stresses in platings and stiffeners are to be in accordance with Table
Table 3.4.5. Allowable Bending Stresses
Structures | Plates | Stiffen-ers |
Bottom, slamming load | 200/ | 180/ |
Bottom, sea load | 180/ | 160/ |
Side structures | 180/ | 160/ |
Deck structures | 180/ | 160/ |
Flat cross structure, slamming load | 200/ | 180/ |
Flat cross structure, sea load | 180/ | 160/ |
Collision bulkhead | 180/ | 160/ |
Superstructure/deckhouse front | 160/ | 140/ |
Superstructure/deckhouse side/deck | 180/ | 160/ |
Watertight bulkhead | 220/ | 200/ |
Deep tank bulkhead | 180/ | 160/ |
502. Minimum thickness
The thickness of structures is normally not to be mula :
less than that obtained from the following for-
mm
: Yield stress N mm at 0.2% offset for unwelded
is not to be taken greater than 70% of the ultimate tensile strength.
: basic stiffener spacing, as following formula, however, is not to be taken less than or greater than 1.0.
m
: as defined in Table 3.4.6.
Table 3.4.6. Values of
Structures |
|
| |
Shell plating | Bottom, bilge and side to load line | 4.0 | 0.03 |
Side above load line | 3.5 | 0.02 | |
Bottom aft in way of rudder, shaft brackets etc. | 10.0 | 0.10 | |
Deck and inner bottom plating | Strength deck weather part forward of amidships | 3.0 | 0.03 |
strength deck weather part aft of amidships | 2.5 | 0.02 | |
Inner bottom | 3.0 | 0.03 | |
Inner bottom of cargo hold | 4.0 | 0.03 | |
Accommodation deck | 2.0 | 0.02 | |
Deck for cargo | 4.0 | 0.03 | |
Superstructure and deckhouse decks | 1.0 | 0.01 | |
Bulkhead plating | Collision bulkhead | 3.0 | 0.03 |
Tank bulkhead | 3.0 | 0.03 | |
Other watertight bulkhead | 3.0 | 0.02 | |
Superstructure and deckhouse front | 3.0 | 0.01 | |
Superstructure and deckhouse sides and aft | 2.5 | 0.01 | |
Others | Foundations | 3.0 | 0.08 |
Structures not mentioned above | 3.0 | 0.0 | |
503. Thickness of platings
1. The general requirement to thickness formula :
of plating subject to lateral pressure is given by the following
mm
correction factor for aspect ratio of plating field and degree of fixation of plate edges, giv- en in Table 3.4.7.
stiffener spacing (m ).
: design pressure, given in Ch 2, Sec 3.
allowable stress, given in Table 3.4.5.
Table 3.4.7 Values of
Aspect ratio | < | 0.5 | Aspect ratio | = | 1.0 | |||||||
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Clamped | along | all | edges | 500 | 342 | 75 | 250 | 310 | 310 | 130 | 130 | |
Longest edge clamped, edge simply supported | shortest | 500 | 0 | 75 | 250 | 425 | 0 | 140 | 200 | |||
: stress at midpoint of longest edge. : stress at midpoint of shortest edge. : maximum field stress parallel to longest edge. : maximum field stress parallel to shortest edge. | ||||||||||||
2. The thickness requirement for a plating field clamped along all edges with an aspect ratio ≤ 0.5 is given by the following formula :
mm
and : as given in Par 1.
3. The thickness of the bottom plating is not to be less than that obtained from the
:
following formula
mm
: correction factor for aspect ratio of plate field, as following Table 3.4.8
Table 3.4.8
|
|
1.0 = | 0.72 |
0.4 < < | (1.1 - 0.25 |
= 0.4 | 1.0 |
: correction factor for curved plating, as following
:
:
radius of curvature (m ).
slamming pressure (kN m ), as given in Ch 2. allowable stress (N mm ) in bottom plating, as following formula .
: stiffener span (m )
4. Above the slamming area, the thickness may be gradually reduced to the ordinary requirement at side. For yacht with rise of floor, however, reduction will not be accepted below the bilge curva- ture or chine.