LICENCIATURA EM ENGENHARIA E ARQUITECTURA
NAVAL
Dimensionamento de Estruturas Navais
Project Work
The midship section of a containership has to be designed based on DnV Classification
Society Rules. The midship section design covers several steps of calculations and to
facilitate the project work the steps of calculations needed are briefly described here.
HULL SECTION SCANTLINGS ACCORDING TO DNV RULES
Hull scantlings section of the containership has to be generated in accordance with DNV Rule
requirements concerning the hull girder strength and local strength.
The following requirements have to be fulfilled:
•
Hull girder strength.
•
Local strength of plates, longitudinals and transverse stiffeners in bottom, side, decks,
bulkheads, inner bottom and other longitudinal structures.
•
Local strength of plates and stiffeners in transverse bulkheads
The requirements are given in Det Norske Veritas' Rules for Classification of Ships. The
most significant chapters for Section Scantlings are included in -Part 3 Chapter 1 Hull
Structural Design - Ships with length 100 metres and above.
The references to those chapters in DNV Rules that are used in hull section scantlings are
given in appendix
In the resulting report of the Hull Section Scantling has to be included:
1.1 Rule Reference
1.2 Input Data
• Length between perpendiculars, Lbp (m)
• Breadth moulded, B (m)
• Dept moulded, D (m)
• Draught moulded, T (m)
• Block coefficient, Cb
1.3 Panel Geometry
1.4 Node Co-ordinates
1.5 Layout of Plates and Profiles
1.6 Cross-Sectional Area
1.7 Cross Sectional Data
• Cross sectional area of the longitudinal elements cm2
• Position of the centroid: Ycg mm
1
• Position of the centroid: Zcg mm
• Moment of inertia about the horiz. Neutral axis, Ih m4
• Moment of inertia about the vert. Neutral axis, Iv m4
• Section Modulus, Bottom, m3
• Section Modulus, Deck line, m3
• Section Modulus, At side, m m3
1.8 Design Bending Moments
• At actual position (from AP)
• Design still water bending moments, Ms kNm
• Design still wave bending moments, Mw kNm
• Design still wave bending moments, Mw for buckling check kNm
• Horizontal wave bending moment acc. to Rules, Mwh kNm
1.9 Hull girder Strength Requirements
• Material strength group
• Yield point of material
• Material factor, f1
• Stress factor, f2
• Minimum vertical extent of HS-steel mm
• Speed factor, Cav
• Sped/flare factor, Caf
• Wave coefficient, Cw
• Wave coefficient, Cwo
• Wave coefficient, Cwu
• At actual position (Midship section)
• Minimum section modulus, Zo
• Section modulus requirement based on design bending moments:
• Sagging kNm m3
• Hogging kNm m3
• Rule section modulus m3
• Combined stresses at bilge and deck corners N/mm2
• Minimum moment of inertia m4
• Minimum section modulus at side m3
• Design bending moments used as basis for the Rule Section moduli:
• Bottom (sagging) Still water kNm
• Deck (sagging): Still water kNm
1.10 Compartments and loads
1.11 Summary of Data Involved in the Local Rule Requirements
1.12 Local Rule Requirements- Plates
1.13 Local Rule Requirements- Stiffeners
1.14 Analysis of Primary Hull Girder Stresses
REFERENCES TO THOSE CHAPTERS IN DNV RULES THAT ARE USED IN
HULL SECTION SCANTLINGS.
Section 2 Material and Material Protection
Section 3 Design Principles
Section 4 Design Loads
B Ship Motions and Accelerations
B200 Basic Parameters
2
201 The acceleration, sea pressures and hull girder loads have been related to a
wave coefficient
203 A common acceleration parameter is given by:
B300 Surge, sway /yaw and heave accelerations
301 The surge acceleration
302 he combined sway/yaw acceleration
303 The heave acceleration
B400 Roll motion and acceleration
401 The roll angle (single amplitude)
402 The period of roll
403 The tangential roll acceleration
404 The radial roll acceleration may normally be neglected.
B500 Pitch motion and acceleration
501 The pitch angle
502 The period of pitch
503 The tangential pitch acceleration
504 The radial pitch acceleration
B600 Combined vertical acceleration
B700 Combined transverse acceleration
B800 Combined longitudinal accelerations
C Pressure and Forces
Section 5 Longitudinal Strength
B Still Water and Wave Induced Hull Girder Bending Moments and Shear Forces
B100 Still water condition
103 The design stillwater bending moments amidships (sagging and hogging)
104 The design stillwater bending moments amidships for buckling control
105 The design values of stillwater shear forces along the length of the ship
are normally
B200 Wave load condition
201 The rule vertical wave bending moments amidships
202 Vertical wave bending moments amidships, buckling control
203 The Rule values of vertical wave shear forces along the length of the ship
205 The Rule horizontal wave bending moments along the length of the ship
C Bending Strength and Stiffness
C200 Extent of high strength steel (HS-steel)
201 The vertical extent of HS-steel used in deck or bottom
202 The longitudinal extent of HS-steel used in deck or bottom
C300 Section modulus.
302 The midship section modulus about the transverse neutral axis
303 The section modulus requirements about the transverse neutral axis based
on cargo and ballast conditions
305 The midship section modulus about the vertical neutral axis (centre line)
C400 Moment of inertia
401 The midship section moment of inertia about the transverse neutral axis
SECTION 6 Bottom Structures
A 200 Definitions
B Design Load
C 200 Keel plate
3
201 A keel plate
202 The thickness
C 300 Bottom and bilge plating
301 The breadth of strakes
302 The thickness requirement corresponding to lateral pressure
304 The thickness is not to be less than:
306 The thickness of the bilge plate is not to be less than that of the adjacent
bottom and side plates, whichever is the greater.
307 If the bilge plate is not stiffened, or has only one stiffener placed in the
middle of the curved part, the thickness is not to be less than:
C 400 Inner bottom plating
401 The thickness requirement corresponding to lateral pressure
402 The thickness is not to be less than
C 500 Plating in double bottom floors and longitudinal girders
501 The thickness requirement of floors and longitudinal girders forming
boundaries
502 The thickness of longitudinal girders, floors, supporting plates and
brackets is not to be less than:
C 700 Bottom longitudinals
701 The section modulus requirement
703 The thickness of web and flange i
C 800 Inner bottom longitudinals
801 The section modulus requirement
802 The thickness of web and flange is not to be less than
C 900 Stiffening of double bottom floors and girders
901 The section modulus requirement of stiffeners on floors and longitudinal
girders
902 Stiffeners in accordance with the requirement in 901 are assumed to have
end connections.
903 The thickness of web and flange is not to be less than given in 603.
D Arrangement of Double Bottom
D 100 General
101 The height of centre girder and floors at centre line
300 Double bottom with longitudinals
301 Side girders
302 The floor spacing
303 Supporting plates
SECTION 7 Side Structures
A 100 Side plating, general
101 The thickness requirement corresponding to lateral pressure
102 The thickness is not for any region of the ship to be less than:
B Design Load
C 300 Plating and Stiffeners
301 The section modulus requirement
302 The thickness of web and flange is not to be less than
D. Girders
D100 General
101 The thickness of web plates, flanges, brackets and stiffeners of girders is
not to be less than:
4
102 The buckling strength of web plates subject to in- plane compressive and
shear stresses
SECTION 8 Deck Structures
A General
100 Strength deck plating
101 The breadth of stringer plate and strakes
102 The thickness requirement corresponding to lateral pressure
104 The thickness is not to be less than:
B Design Load
C 300 Plating and Stiffeners
SECTION 9 Bulkhead Structures
A General
B Design Load
C 100 Bulkhead plating
101 The thickness requirement corresponding to lateral pressure
102 The thickness is not to be less than:
103 The thickness of longitudinal bulkhead plating is also to satisfy the
buckling strength requirements given in Sec.14
104 In longitudinal bulkheads within the cargo area the thickness is not to be
less than:
C 200 Longitudinals
201 The section modulus requirement for stiffeners and corrugations
202 The web and flange thickness is not to be less than
INPUT DATA
Ship
L (m)
B (m)
D (m)
d (m)
Cb
V (knot)
CT1
105
17.2
8.7
6.5
0.7
15
CT2
122
19.2
10.1
7.6
0.69
16
CT3
100.0
19.00
10.40
7.70
0.70
16
CT4
120.70
20.00
8.70
6.50
0.71
17
CT5
141.20
25.00
13.60
10.00
0.68
18
CT6
151.40
23.00
13.70
9.50
0.70
18
CT7
167.70
26.50
14.40
10.70
0.66
18
CT8
193.25
32.20
18.80
11.20
0.61
20
CT9
233.40
32.20
18.85
9.70
0.66
19
CT10
281.60
32.25
21.40
12.00
0.68
19
CT11
293.0
32.2
22.2
12.2
0.65
24
CT12
305.0
43
22.7
12.5
0.6
25
CT13
320.4
42.85
26.4
14.5
0.63
25.3
CT14
335
43
24.7
13.6
0.64
25.3
DEADLINE FOR SUBMISSION
5
The project report should be submitted in the last practical lecture of the semester.
REFERENCES
• DNV Electronic Rules (2002)
• DEM lecture notes.
6
STANDARD PROFILES
7
8
9
STANDARD PLATES
Thickness, mm Length, [m] as a function of breadth, [mm]
1400 1600
1800
2000
2200
2400
2600
3000
4; 5
6
6
6
6, 7, 8
6, 7, 8
6, 7, 8
7
6
6, 7, 8
6, 7, 8
6, 7, 8
8; 9
6
6, 7, 8
6, 7, 8
6, 7, 8 10
10, 12
10; 11
6
6, 7, 8
6, 7, 8
6, 7, 8 10.1
10, 12
12
6
6, 7, 8, 10 6, 7, 8, 10 6, 7, 8 10, 12 10, 12 10, 12 12
14; 16; 18; 20
6, 7, 8, 10 6, 7, 8, 10 6, 7, 8 10, 12 10, 12 10, 12 12
22; 24; 26
10
10
10
28; 30; 32
6
6, 7, 8
6, 7, 8 12
12
12
12
36; 40
6
12
12
12
12
45; 50; 56
6
10