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Scantling Calculation
Particulars
Frame spacing a=0.5m
Web frame spacing
Length of ship
Breadth of ship
Draft
Height
Block coefficient
Material factor for normal strength hull structure
Bottom shell plating
Length coefficient for length L>90m
Service coefficient for unlimited service range
Distribution factor C F = 1.0 for midship
Wave coefficient C 0
n f = 1.0 for Transverse framing
= 0.83 for Longitudinal framing
Permissible design stress σ perm = 230/K for L>90m
= 230/1.0
= 230
Probability factor = 1.0 for shell plating
Basic external dynamic load p 0 = 2.1 X(C B+ 0.7)X C 0 X C l X f
= 2.1 X(0.6 + 0.7)X 7.92 X 1X 1
= 21.62
Maximum bottom design hull girder bending stress σ LB = 120/k
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= 120/1
= 120
Maximum design shear stress due to longitudinal hull girder bending
σ pl
Vertical distance of the structure load centre from base line z = 3.6485 m
Load on sides
External load on ship’s bottom
Corrosion addition t K for thickness <10mm
The thickness of bottom plating should not be less than the greater of the two followingvalues
Or,
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So we take the thickness of our bottom plate as
Flat keel plating
The thickness of flat plate keel should not be less than
So we take the thickness of our flat plate keel as
Bilge plating
We take the thickness of our bilge plate as
Side shell plating
The thickness of the side shell plating should not be less than the greater of the twofollowing values
Or,
(In this case p = p S)
So we take the thickness of our side shell plating as
Dimension of centre girder
The depth of the centre girder should not be less than
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So we take the depth of centre girder as
The web thickness of the centre girder should not be less than
So we take the thickness of centre girder as
Hence the dimension of the centre girder is
Dimension of side girder
The web thickness of the side girder should not be less than
So we take the thickness of side girder as
Hence the dimension of the side girder is
Thickness of floor plating
The thickness of plate floors is not to be less than
So we take the thickness of floor plating as
Thickness of inner bottom plating
The thickness of inner bottom plating should not be less than
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(In this case )
So we take the thickness of inner bottom as
Dimension of main frame
Length of unsupported span
Maximum height of curve s = 0 for main frame
for L>90m
Factor for curved frames
Here,
The section modulus of main frame should not be less than
(In this case )
So we take the section modulus of main frame as
Hence the dimension of the main frame L-section is
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Dimension of web frame
Web frame spacing
The section modulus of web frames should not be less than
So we take the section modulus of web frame as
Hence the dimension of the web frame T -section is
Dimension of side stringer
We take the dimension of side stringer same as that of the web frame
Hence dimension of the side stringers are
Dimension of deck beam
Vertical distance of the load centre of the structure above base line
The load on weather deck,
Length of unsupported span
for beams and girders
The section modulus of deck beam should not be less than
(In this case )
So we take the section modulus of deck beam as
Hence the dimension of the deck beam L-section is
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Dimension of deck girder
The section modulus of deck girder should not be less than
(In this case )
So we take the section modulus of deck girder as
Hence the dimension of the deck girder T-section is
Dimension of deck web
The section modulus of deck girder should not be less than
(In this case )
So we take the section modulus of deck girder as
Hence the dimension of the deck girder T-section is
Thickness of deck plate
The speed of ship
for midship
So,
Hence acceleration addition
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Mean deck height
Static load on cargo
So, The load on cargo deck
The plate thickness of deck plate should not be less than
So we take the thickness of deck plate as
Dimension of brackets
Here for bottom frames
Unsupported span
The section modulus of bottom and inner bottom frames should not be less than
For flanged bracket
The thickness of the bracket should not be less than
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So we take the thickness of the brackets as
Now
The arm length of brackets should not be less than
So we take the arm length of bracket as
Dimension of longitudinals
We have
Unsupported span
Hence
0.783
Again
.245
Now
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Here
And assuming
The section modulus of bottom longitudinal should not be less than
So we take the section modulus of bottom longitudinal as
Hence the dimension of the bottom longitudinal is
In case of side shell
Unsupported span
The section modulus of side longitudinal should not be less than
So we take the section modulus of side longitudinal as
Hence the dimension of the side longitudinal is
Thickness of bulkhead plating:
Here for bulkheads
We, assume
So,
Spacing of stiffeners
Here, 4.4485m
So,
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The thickness of bulkhead plating should not be less than
So we take the thickness of transverse bulkhead as
We also take the thickness of longitudinal bulkhead as
Dimension of stiffeners:
Here
The section modulus of stiffeners should not be less than
So we take the dimension of the stiffener as
Dimension of stem
The cross-sectional area of bar stem should not be less than
So we take the cross-sectional area of bar stem as
Hence the dimension of bar stem as we take is
Keel plate width
The width of flat keel plate should not be less than
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So we take the width of flat keel plate as
Hence the half width of flat keel plate as we take is
Shear strake width
The width of shear strake should not be less than
So we take the width of shear strake as
The thickness of shear strake should not be less than the greater of the following twovalues
Or,
So we take the thickness of the shear strake as