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DNV GL AS

RULES FOR CLASSIFICATION

ShipsEdition October 2015

Part 3 Hull

Chapter 6 Hull local scantling

FOREWORD

DNV GL rules for classification contain procedural and technical requirements related to obtainingand retaining a class certificate. The rules represent all requirements adopted by the Society asbasis for classification.

© DNV GL AS October 2015

Any comments may be sent by e-mail to [email protected]

If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of DNV GL, then DNV GL shallpay compensation to such person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to tentimes the fee charged for the service in question, provided that the maximum compensation shall never exceed USD 2 million.

In this provision "DNV GL" shall mean DNV GL AS, its direct and indirect owners as well as all its affiliates, subsidiaries, directors, officers,employees, agents and any other acting on behalf of DNV GL.

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Rules for classification: Ships — DNVGL-RU-SHIP-Pt3Ch6. Edition October 2015 Hull local scantling

DNV GL AS

CHANGES – CURRENT

This is a new document.

The rules enter into force 1 January 2016.

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CONTENTS

Changes – current...................................................................................................... 3

Section 1 General....................................................................................................... 61 Application..............................................................................................6

1.1 Application.......................................................................................... 61.2 Acceptance criteria............................................................................... 6

Section 2 Load application......................................................................................... 71 Load combination................................................................................... 7

1.1 Hull girder stress................................................................................. 71.2 Lateral pressures................................................................................. 71.3 Pressure combination........................................................................... 7

2 Design load sets..................................................................................... 72.1 Application of load components..............................................................8

Section 3 Minimum thicknesses............................................................................... 161 Plating.................................................................................................. 16

1.1 Minimum thickness requirements..........................................................162 Stiffeners and tripping brackets........................................................... 17

2.1 Minimum thickness requirements..........................................................173 Primary supporting members............................................................... 17

3.1 Minimum thickness requirements..........................................................17

Section 4 Plating...................................................................................................... 191 Plating subjected to lateral pressure....................................................19

1.1 General............................................................................................. 191.2 Plating of corrugated bulkheads........................................................... 20

2 Special requirements............................................................................ 222.1 Bilge plating...................................................................................... 222.2 Side shell plating in aft- and forebody.................................................. 23

Section 5 Stiffeners.................................................................................................. 251 Stiffeners subject to lateral pressure................................................... 25

1.1 General............................................................................................. 251.2 Beam analysis....................................................................................28

Section 6 Primary supporting members and pillars..................................................30

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1 General................................................................................................. 301.1 Application.........................................................................................30

2 Primary supporting members beam analysis........................................ 302.1 Scantling requirements....................................................................... 302.2 Advanced calculation methods............................................................. 32

3 Pillars....................................................................................................343.1 Pillars subjected to compressive axial load............................................ 343.2 Pillars subject to tensile axial load........................................................34

Section 7 Intersection of stiffeners and PSM........................................................... 351 Stiffener connections............................................................................35

1.1 Arrangement of cut-outs..................................................................... 351.2 Connection of stiffeners to PSM........................................................... 381.3 Simplified calculation of connection of stiffeners to PSM...........................42

Section 8 Superstructure, deckhouse and companionways.......................................451 General................................................................................................. 45

1.1 Application.........................................................................................452 Structural arrangement........................................................................ 46

2.1 Structural continuity........................................................................... 462.2 End connections................................................................................. 472.3 Local reinforcement on bulkheads........................................................ 472.4 Exposed sides of superstructure sides...................................................47

3 Scantlings............................................................................................. 473.1 Minimum thicknesses and minimum section modulus.............................. 473.2 Plating.............................................................................................. 483.3 Stiffeners...........................................................................................483.4 Primary supporting members............................................................... 483.5 Aluminium deckhouse or superstructure................................................ 50

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SECTION 1 GENERAL

1 Application

1.1 Application

1.1.1 This chapter applies to hull structure over the full length of the ship.

1.1.2 This chapter provides requirements for evaluation of plating, stiffeners and primary supportingmembers (PSM) subject to lateral pressure, local loads and hull girder loads, as applicable. Requirements arespecified for:

— load application in Sec.2— minimum thickness of plates, stiffeners and PSM in Sec.3— plating in Sec.4— stiffeners in Sec.5— PSM and pillars in Sec.6— intersection of stiffeners and PSM in Sec.7— superstructure and deckhouse in Sec.8.

In addition, other requirements not related to defined design load sets, are provided.

1.1.3 Required scantlingsThe offered net scantling shall be greater than or equal to the required scantlings based on requirementsprovided in this chapter.

1.1.4 Additional local strength requirementsAdditional local strength requirements are provided in Ch.10 considering sloshing, impact loads (bow impact,bottom slamming and liquid impact in tanks), special cargo loads (steel coil and wheel loading) and additionallocal strength requirement for various structural members.

1.2 Acceptance criteria

1.2.1 Acceptance criteria shall be selected as defined in Sec.2 Table 1 and Sec.2 Table 2.

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SECTION 2 LOAD APPLICATIONSymbolsFor symbols not defined in this section, refer to Ch.1 Sec.4.

1 Load combination

1.1 Hull girder stress1.1.1 Hull girder stress applicable for load components SThe hull girder stress σhg, in N/mm2, for load component S shall be taken as:

where:

σhg-sw = hull girder bending stress, in N/mm2, due to vertical still water bending moment as defined inCh.5 Sec.3 [2] for ships without large deck openings and in Ch.5 Sec.3 [3] for ships with largedeck openings.

1.1.2 Hull girder stress applicable for load components S+DThe hull girder stress σhg, in N/mm2, for load components S+D shall be taken as defined in Ch.5 Sec.3 [2] forships without large deck openings and in Ch.5 Sec.3 [3] for ships with large deck openings.

1.2 Lateral pressures1.2.1 Static and dynamic pressures in intact conditionsThe static and dynamic lateral pressures, as defined in Ch.4, in intact condition induced by the sea and thevarious types of cargoes, ballast and other liquids shall be considered. Applied loads will depend on thelocation of the elements under consideration, and the adjacent type of compartments.

1.2.2 Lateral pressure in flooded conditionsWatertight boundaries of compartments not intended to carry liquids, excluding hull envelope, shall besubjected to lateral pressure in flooded conditions. Compartments intended to carry liquids which haveoverflow height below freeboard deck shall also be checked for lateral pressure in flooded conditions.

1.3 Pressure combination1.3.1 Elements of the outer shellIf the compartment adjacent to the outer shell is intended to carry liquids, the static and dynamic lateralpressures to be considered are the differences between the internal pressures and the external sea pressuresat the corresponding draught.If the compartment adjacent to the outer shell is not intended to carry liquids, the internal pressures andexternal sea pressures shall be considered independently.

1.3.2 Elements other than those of the outer shellExcept as specified in [1.3.1], the static and dynamic lateral pressures on an element separating twoadjacent compartments are those obtained considering the two compartments individually loaded.

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2 Design load sets

2.1 Application of load components2.1.1 ApplicationThese requirements apply to:

— plating and stiffeners along the full length of the ship— primary supporting members, if scantlings are not determined by global FE analysis or partial ship

structural FE analysis— plating, stiffeners and primary supporting members in superstructures and deckhouses contributing to hull

girder longitudinal strength

2.1.2 Load componentsThe static and dynamic load components shall be determined in accordance with Ch.4 Sec.7 Table 1.Radius of gyration, kr, and metacentric height, GM, shall be in accordance with Ch.4 Sec.3 for the consideredloading conditions specified in the design load sets given in Table 1.

2.1.3 Design load sets for plating and stiffenersStatic and dynamic design load sets for plating and stiffeners are given in Table 1. Impact and sloshing loadsets are considered in Ch.10.In addition, design load sets for specific ship types are given in Pt.5.

Table 1 Design load sets

Designload set

Designload

scenarioLoad component4) Draught Acceptance

criteria

Loadingcondition fordefinition ofGM and kr

External shell andexposed deck

PS+ PW , PD

Superstructure side

SEA-1

2

max(PW;PSI)

TSC

AC-II

Full Loadcondition

External shell SEA-2 1 PS TSC AC-I -

WB-1 2 Pls-1 +Pld – (PS+PW)1) TBAL AC-IINormalballast

condition

WB-2 3Pls-2 +Pld – (PS+PW)1)

TBAL AC-II

Normalballast

condition

WB-3 4 max(Pls-4;Pls-ST) – PS1) max(TBAL;

0.25TSC)AC-III -

Boundaries of waterballast tanks and ballastholds

WB-4 1 Pls-3 - PS1) max(TBAL;

0.25TSC)AC-I -

Str

uctu

ral m

embe

r

Boundaries of tanksother than ballast watertanks

TK-1 2 Pls-1 +Pld – (PS+PW)(1) TBAL AC-IINormalballast

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Designload set

Designload

scenarioLoad component4) Draught Acceptance

criteria


TK-2 4 Pls-ST – PS1)

max(TBAL;

0.25TSC)AC-III

TK-3 1 Pls-3 - PS1)

max(TBAL;

0.25TSC)AC-I -

Internal structures intanks INT-1 1 Pint TSC AC-I -

Collision bulkhead AC-I

Watertight boundariesother than collisionbulkhead

FD-1 5 Pfs TDAMAC-III

-

UDL-12) 2

Pdl-s + Pdl-d

FU-s + FU-dTBAL

3) AC-IINormalballast

condition3)Exposed decks andnon-exposed decks andplatforms with distributedload UDL-2

2) 1Pdl-s

FU-s- AC-I -

1) (PS+PW) and PSshall be considered for external shell only.2) Distributed or concentrated loads only. Need not to be combined with simultaneously occurring green sea pressure.3) For cargo loads, draught, GM and kr values may be based on actual cargo conditions in the loading manual.4) Local loads:

PS = hydrostatic sea pressure as given in Ch.4 Sec.5 [1.2]PW = wave pressure as given in Ch.4 Sec.5 [1.3]PD = external dynamic design pressure for exposed decks and wheelhouse top due to green sea loading

as given in Ch.4 Sec.5 [2.2] and Ch.4 Sec.5 [3.2], respectivelyPA = design pressure for aft- and forward external bulkheads of superstructure and deckhouse walls as

given in Ch.4 Sec.5 [3.4]PSI = external design pressure for external side of superstructure as given in Ch.4 Sec.5 [3.4]Pls-1 = static tank pressure during normal operations at sea as given in Ch.4 Sec.6 [1.2.1]Pls-2 = static tank pressure during flow through ballast water exchange as given in Ch.4 Sec.6 [1.2.2]Pls-3 = static tank pressure during normal operations at harbour/sheltered water as given in Ch.4 Sec.6

[1.2.3]Pls-4 = static tank pressure during overfilling of ballast water tanks as given in Ch.4 Sec.6 [1.2.4]Pls-ST = static tank testing pressure as given in Ch.4 Sec.6 [1.2.5]Pfs = static tank pressure in flooded condition as given in Ch.4 Sec.6 [1.2.7]Pld = dynamic tank pressure as given in Ch.4 Sec.6 [1.3]Pint = minimum pressure for internal structures in tanks as given in Ch.4 Sec.6 [3.1]Pdl = pressure due to distributed deck load as given in Ch.4 Sec.5 [2.3.1] or Ch.4 Sec.6 [2.2.1]FU = force on exposed and non-exposed decks and platforms due to unit loads as given in Ch.4 Sec.5

[2.3.2]

2.1.4 Design load sets for primary supporting members

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Design load sets to be applied for primary supporting members are described in Table 2. The load sets are ingeneral to be based on the net load acting on the PSM of double- and single skin type.In addition, design load sets for specific ship types are given in Pt.5.Design loading conditions in FE analysis are described in Ch.7 Sec.1 in general and for specific ship types aregiven in Pt.5.

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Part 3 Chapter 6 Section 2

Table 2 Design load sets for primary supporting members

Load componentDescription Primary supporting members Designload set

Local load 10) Hull girderload

Draught Acceptancecriteria

Loadingcondition

fordefinition

of GMand kr

Load pattern

Vertical side web frames/floors SEA-1

Pex 1)- (Pdl-s +

Pdl-d) or (FU-s+ FU-d

1)8))N/A

SEA-1h Pex 2)- (Pdl-s +


2)8))

Mwv-h + Msw-h 2)

SEA-1h Pex 3)- (Pdl-s +


3)8))

Mwv-h + Msw-h 3)

SEA-1s Pex 2)- (Pdl-s +


2)8))

Mwv-s + Msw-s 2)

Exte

rnal

she

ll (e

mpt

yta

nks)

, ex

clud

ing

deck

s

Bottom and side girders/grillage

SEA-1s Pex 3)- (Pdl-s +


3)8))

Mwv-s + Msw-s 3)

TSC AC-II

Full

load

con

ditio

n

Vertical side web frames/floors TK-1,

WB-1

Pin - Pex 1) 4)

5)- (Pdl-s + Pdl-

d) or (FU-s +FU-d

1)8))

N/A

TK-1h,WB-1h

Pin - Pex 2) 4)

5)- (Pdl-s + Pdl-

d) or (FU-s +FU-d

1)8))

Mwv-h + Msw-h 2)

TK-1h,WB-1h

Pin - Pex3)4) 5)-

(Pdl-s + Pdl-d)or (FU-s + FU-

d1)8))

Mwv-h + Msw-h 3)

Exte

rnal

she

ll (t

ank

pres

sure

incl

uded

)ex

clud

ing

deck

s


TK-1s,WB-1s

Pin - Pex 2) 4)

5)- (Pdl-s + Pdl-

d) or (FU-s +FU-d

1)8))

Mwv-s + Msw-s 2)

TBAL AC-II

Nor

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Loadingcondition

fordefinition

of GMand kr

Load pattern

TK-1s,WB-1s

Pin - Pex 3) 4)

5)- (Pdl-s + Pdl-

d) or (FU-s +FU-d

1)8))

Mwv-s + Msw-s 3)

Vertical side web frames/floors

TK-3,WB-4

Pin - Pex 1) 4)

5)- Pdl-s,FU-s1)8)

N/A

TK-3h,WB-4h

Pin - Pex 2) 4)

5)- Pdl-s,FU-s2)8)

Msw-h

TK-3h,WB-4h

Pin - Pex3) 4) 5)-

Pdl-s,FU-s3)8)

Msw-h

TK-3s,WB-4s

Pin - Pex 2) 4)

5)- Pdl-s,FU-s2)8)

Msw-s


TK-3s,WB-4s

Pin - Pex 3) 4)

5)- Pdl-s,FU-s3)8)

Msw-s

TBAL AC-I -


TK-2,WB-3

Pin - Pex 1) 4) 5)

N/A

TK-2h,WB-3h

Pin - Pex 2) 4) 5)

Msw-h

TK-2h,WB-3h

Pin - Pex3) 4) 5)

Msw-h

TK-2s,WB-3s

Pin - Pex 2) 4) 5)

Msw-s


TK-2s,WB-3s

Pin - Pex3) 4) 5)

Msw-s

TBAL AC-III -


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Loadingcondition

fordefinition

of GMand kr

Load pattern

Vertical side web frames SEA-1 Pex , PSI 1) 9) N/A

SEA-1h Pex , PSI 2) 9) Mwv-h + Msw-h

2)

SEA-1h Pex , PSI 3) 9) Mwv-h + Msw-h

3)

SEA-1s Pex , PSI 2) 9) Mwv-s + Msw-s

2)

Sup

erst

ruct

ure

side

Longitudinal stringers/grillage

SEA-1s Pex , PSI 3) 9) Mwv-s + Msw-s

3)

TSC AC-II -

Transverse deck girders SEA-1 Pex , PD 1) N/A

SEA-1h Pex , PD 2) Mwv-h + Msw-h

2)

SEA-1h Pex , PD 3) Mwv-h + Msw-h

3)

SEA-1s Pex , PD 2) Mwv-s + Msw-s

2)

Exte

rnal

dec

ks a

ndpl

atfo

rms,

incl

udin

gsu

pers

truc

ture

(gr

een

sea

pres

sure

onl

y) Longitudinal deck girders/grillage

SEA-1sPex , PD

3)Mwv-s + Msw-s

3)

TSC AC-II

Full

load

con

ditio

n

Transverse deck girders UDL-1 Pdℓ-s + Pdℓ-d

FU-s + FU-d 1) 8) N/A

UDL-1h Pdℓ-s + Pdℓ-d

FU-s + FU-d 2) 8)

Mwv-h + Msw-h 2)

UDL-1h Pdℓ-s + Pdℓ-d

FU-s + FU-d 3) 8)

Mwv-h + Msw-h 3)

UDL-1s Pdℓ-s + Pdℓ-d

FU-s + FU-d 2) 8)

Mwv-s + Msw-s 2)

Longitudinal deck girders/grillage

UDL-1s Pdℓ-s + Pdℓ-d

FU-s + FU-d 3) 8)

Mwv-s + Msw-s 3)

TBAL AC-II

Nor

mal

bal

last

con

ditio

n

Dis

trib

uted

dec

k lo

ad o

nin

tern

al o

r ex

tern

al d

ecks

(adj

acen

t ta

nks

empt

y)

Transverse deck girders UDL-2 Pdℓ-s ,FU-s 1) 8) N/A TBAL AC-I -


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Loadingcondition

fordefinition

of GMand kr

Load pattern

Longitudinal deck girders/grillage

UDL-2h Pdℓ-s , FU-s 2)8) Msw-h

2)

UDL-2s Pdℓ-s , FU-s 3)8) Msw-s

3)

Decks and transversebulkheads: stringers/verticalweb frames/grillage andtransverse deck girders

TK-1,WB-1 Pin

1) 4) 6) N/A

Longitudinal bulkheads:vertical web frames

TK-1,WB-1 Pin

1) 4) 6) N/A

TK-1h,WB-1h Pin

2) 4) 6) Mwv-h + Msw-h 2)

TK-1h,WB-1h Pin

3) 4) 6) Mwv-h + Msw-h 3)

TK-1s,WB-1s Pin

2) 4) 6) Mwv-s + Msw-s 2)

Decks and longitudinalbulkheads:girders/grillage

TK-1s,WB-1s Pin

3) 4) 6) Mwv-s + Msw-s 3)

TBAL AC-II

Nor

mal

bal

last

con

ditio

n


TK-3,WB-4 Pin

1) 4) 6) N/A

Longitudinalbulkheads:vertical webframes

TK-3,WB-4 Pin

1) 4) 6) N/A

TK-3h,WB-4h Pin

4) 6) Msw-hDecks and longitudinalbulkheads:girders/grillage TK-3s,

WB-4s Pin 4) 6) Msw-s

TBAL AC-I -

Tank

bou

ndar

ies

and/

orw

ater

tight

bou

ndar

ies

(exc

ludi

ng e

xter

nal

shel

l)in

clud

ing

expo

sed

deck

s


TK-2,WB-3

Pin - Pex 1) 4) 5)

N/A TBAL AC-III -


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Loadingcondition

fordefinition

of GMand kr

Load pattern

TK-2h,WB-3h

Pin - Pex 2) 4) 5)

Msw-h

TK-2h,WB-3h

Pin - Pex3) 4) 5)

Msw-h

TK-2s,WB-3s

Pin - Pex 2) 4) 5)

Msw-s


TK-2s,WB-3s

Pin - Pex3) 4) 5)

Msw-s


FD-1 Pin 1) 7) N/A

Longitudinalbulkheads:vertical webframes

FD-1 Pin 1) 7) N/A

FD-1h Pin7) Msw-hDecks and longitudinal

bulkheads:girders/grillageand transverse deck girders FD-1s Pin

7) Msw-s

TDAM AC-III -

1) The EDW giving the highest pressure to be applied.2) The EDW giving the highest pressure with corresponding bending moment to be applied.3) The EDW giving the highest bending moment with corresponding pressure to be applied.4) Pin shall also cover water ballast and bulk cargo hold loads.5) Pexshall be considered for external shell only.6) Pressure from one side only. Full tank with adjacent tank empty.7) Flooded pressure is not applicable to external shell. Pressure from one side only. Full tank with adjacent tank empty. The boundaries of void and

dry spaces not forming part of hull external shell shall be evaluated using Design Load Sets FD-1, FD-1h and FD-1s.8) Distributed or concentrated loads only. Need not to be combined with simultaneously occurring green sea pressure.9) PSI is design pressure for external sides of superstructure and deckhouse.10) Local loads are described in Ch.4 Sec.2 Table 1.

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SECTION 3 MINIMUM THICKNESSESSymbolsFor symbols not defined in this section, refer to Ch.1 Sec.4.

1 Plating

1.1 Minimum thickness requirements

1.1.1 The net thickness of plating, in mm, shall comply with the minimum thickness requirement given by:

where:

a = coefficient as defined in Table 1b = coefficient as defined in Table 1

Table 1 Minimum net thickness for plating

Element Location a b

Keel 5.0 0.05

Bottom and bilge 4.5 0.035

From upper end of bilge plating to TSC + 4.6m 0.035

From TSC + 4.6m to TSC + 6.9m 0.025

Side shell

Elsewhere

4.0

0.01

Shell

Sea chest boundaries 4.5 0.05

Weather deck1),2),3),4), strength deck2),3) and platform deck in machinery space 0.02

Boundary for cargo tanks, water ballast tanks and hold intended for cargo in bulk 0.015Deck

Other decks3),4),5)

4.5

0.01

Cargo spaces loaded through cargo hatches except container holds 5.5 0.025Innerbottom Other spaces 4.5 0.02

Bulkheads for cargo tanks, water ballast tanks and hold intended for cargo in bulk

Peak bulkheads and machinery space end bulkheads0.015

Watertight bulkheads and other tanks bulkheads

4.5

0.01

Non-tight bulkheads in tanks 0.005

Bulkheads

Other non-tight bulkheads5.0

0

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Element Location a b

1) For weather deck forward of 0.2 L from F.E, b is not to be taken less than 0.01.2) For two continuous decks arranged above 0.7 D from baseline b may be reduced by 0.01.3) For more than two continuous decks arranged above 0.7 D from baseline b may be taken equal to 0.4) For the decks not contributing to hull girder longitudinal strength, b may be taken equal to 0.5) For cargo decks sheltered with wood or an approved composition, a may be taken equal to 4.0.

Minimum thicknesses for deckhouses and superstructures are specified in Sec.8 [3.1].

2 Stiffeners and tripping brackets


2.1.1 The net thickness of the web and face plate, if any, of stiffeners and tripping brackets in mm, shallcomply with the minimum net thickness given in Table 2.In addition, the net thickness of the web of stiffeners and tripping brackets, in mm, shall be:

— not less than 40% of the net required thickness of the attached plating, to be determined according toSec.4

Table 2 Minimum net thickness for stiffeners and tripping brackets

Element Location Net thickness

Tank boundary 3.0 + 0.015 L2

Structures in deckhouse and superstructure and decks forvessels with more than 2 continuous decks above 0.7 Dfrom baseline

4.0Stiffeners and attached end brackets

Other structure 3.5 + 0.010 L2

Tripping brackets 3.0 + 0.015 L2

3 Primary supporting members


3.1.1 The net thickness of web plating and flange of primary supporting members in mm, shall comply withthe appropriate minimum thickness requirements given by:

where:

a = coefficient as defined in Table 3b = coefficient as defined in Table 3

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Table 3 Minimum net thickness for primary supporting members

Element a b

Bottom centreline girder and lower strake of centreline wash bulkhead 5.0 0.03

Other bottom girders 5.0 0.017

Floors 5.0 0.015

Floors in peak tanks 5.0 0.0251)

PSM supporting side shell, ballast tank, cargo tank and hold intended for cargoin bulk2),3), 4.5 0.015

Other PSM 4.5 0.01

1) The value of bL2 does not need to be greater than 5.0.2) For stringers in double side next to dry space not intended for cargo in bulk, the value of bL2 does not need to be

taken greater than 2.5.3) Other specific requirements related to ship types are given in Pt.5.

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SECTION 4 PLATINGSymbols

For symbols not defined in this section, refer to Ch.1 Sec.4.

αp = correction factor for the panel aspect ratio to be taken as follows but not to be taken greater than1.0:

a = length of plate panel, in mm, as defined in Ch.3 Sec.7 [2.1.1]b = breadth of plate panel, in mm, as defined in Ch.3 Sec.7 [2.1.1]P = design pressure for the considered design load set, see Sec.2 [2], calculated at the load calculation

point defined in Ch.3 Sec.7 [2.2], in kN/m2

σhg = hull girder stress, in N/mm2, as defined in Sec.2 [1], calculated at the load calculation point asdefined in Ch.3 Sec.7 [2.2]

1 Plating subjected to lateral pressure

1.1 General1.1.1 PlatingThe net thickness, in mm, shall not be taken less than the greatest value for all applicable design load sets,as defined in Sec.2 [2.1.3], given by:

where:

Ca = permissible bending stress coefficient for plate taken equal to:

not to be taken greater than Ca-max

βa = coefficient as defined in Table 1αa = coefficient as defined in Table 1Ca-max = maximum permissible bending stress coefficient as defined in Table 1

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Table 1 Plating definition of βa, αa and Ca-max

Acceptance criteria Structural member βa αa Ca-max

Longitudinal stiffened plating 0.90 0.50 0.80Longitudinal members

Transverse stiffened plating 0.90 1.00 0.80AC-I

Other members 0.80 0.00 0.80


Transverse stiffened plating 1.05 1.00 0.95AC-II



Transverse stiffened plating 1.10 1.00 1.00AC-III


1.2 Plating of corrugated bulkheads1.2.1 Cold and hot formed corrugationsThe net thicknesses, in mm, of the web and flange plates of corrugated bulkheads shall not be taken lessthan the greatest value calculated for all applicable design load sets, as defined in Sec.2 [2.1.3], given by:

where:

bp = breadth of plane corrugation plating:bp = a for flange plating, in mm, as defined in Ch.3 Sec.6 Figure 9bp = c for web plating, in mm, as defined in Ch.3 Sec.6 Figure 9

CCB = permissible bending stress coefficient for corrugated bulkhead plating taken equal to:

not to be greater than CCB-max

βCB = coefficient as defined in Table 2αCB = coefficient as defined in Table 2CCB-max = maximum permissible bending stress coefficient as defined in Table 2

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Table 2 Corrugations, definition of βCB, αCB and CCB-max

Acceptance criteria Structural member βCB αCB CCB-max

Horizontally corrugated longitudinal bulkheads 0.90 0.50 0.75AC-I

Other corrugated bulkheads 0.75 0.00 0.75

Horizontally corrugated longitudinal bulkheads 1.05 0.50 0.90AC-II


Horizontally corrugated longitudinal bulkheads 1.10 0.50 0.95AC-III


1.2.2 Built-up corrugationsFor built-up corrugations, with flange and web plate of different thickness, the net thickness, in mm, shall betaken as the greatest value calculated for all applicable design load sets, as defined in Sec.2 [2.1.3], givenby:

where:

t1 = net thickness of the thicker plating, either flange or web, in mmt2 = net required thickness of the thinner plating, either flange or web, not to be less than required by

[1.2.1], in mmbP = breadth of thicker plate, either flange or web, in mmCCB = permissible bending stress coefficient as defined in [1.2.1]

1.2.3 Section modulus of corrugationsThe requirements given in the following apply to corrugations of bulkheads.

As an alternative the strength of the corrugations may be verified by direct strength assessment inaccordance with Sec.6 [2].

The net section modulus, in cm3, of corrugated bulkheads subjected to lateral pressure shall not be less thanthe value obtained from the following formula:

where:

P = design pressure for the design load set as defined in Sec.2 Table 1 and calculated at the loadcalculation point defined in Ch.3 Sec.7 [3.2] in kN/m2

sC = half pitch length, in mm, of the corrugation, as defined in Ch.3 Sec.6 Figure 9ℓbdg = effective bending span, in m, as defined in Ch.3 Sec.6 [5.1.4]fbdg = bending moment factor given in Sec.6 Table 1. More exact value may be based on direct

calculationsCs = permissible bending stress coefficient as defined in Table 3 for the design load set being

considered, to be taken as:

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not to be greater than CS-max

Cs-max = coefficient, as defined in Table 3αs = coefficient, as defined in Table 3βs = coefficient, as defined in Table 3σcx' = ultimate buckling stress, in N/mm2, of corrugation flange as defined in the Society's document

DNVGL-CG-0128Buckling [3.2.2.3] applying buckling coefficients given in the Society's documentDNVGL-CG-0128Buckling [3.3]

Table 3 Corrugations, definition of βs, αs and Cs-max

Acceptance criteria Structural member βs αs Cs-max

Longitudinal horizontal corrugations 0.85 1.00 0.75AC-I

Other corrugations 0.75 0.00 0.75

Longitudinal, horizontal corrugations 1.00 1.00 0.85AC-II


Longitudinal horizontal corrugations 1.00 1.00 0.90AC-III


2 Special requirements

2.1 Bilge plating2.1.1 Thickness of bilge platingThe thickness of plating in bilge area as defined in Ch.1 Sec.4 [3.8]shall be equal or greater than the lesserof [1.1.1] and [2.1.3], and shall also satisfy [2.1.2].

2.1.2 The net thickness of the bilge plate shall not be less than that of the required adjacent bottom and sideplates, whichever is the greater.

2.1.3 Thickness of bilge plating without longitudinal stiffeningThe net thickness of bilge plating without longitudinal stiffening, in mm, shall not be taken less than:

where:

Pex = design sea pressure for the design load set SEA-1 as defined in Sec.2 [2.1.3] calculated at the lowerturn of the bilge, in kN/m2

R = effective bilge radius, in mm, taken as:

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R0 = radius of curvature, in mm. See Figure 1Δs1 = distance between the lower turn of bilge and the outermost bottom longitudinal, in mm, see Figure

1. Where the outermost bottom longitudinal is within the curvature, this distance shall be taken aszero

Δs2 = distance between the upper turn of bilge and the lowest side longitudinal, in mm, see Figure 1.Where the lowest side longitudinal is within the curvature, this distance shall be taken as zero

sb = distance between transverse stiffeners, webs or bilge brackets, in mm

A bilge keel is not considered as an effective ‘longitudinal stiffening’ member.

2.1.4 Transverse extension of bilge minimum plate thicknessWhere a plate seam is located in the straight plate just below the lowest stiffener on the side shell, anyincreased thickness required for the bilge plating does not have to be extended to the adjacent plate abovethe bilge provided the plate seam is not more than s2/4 below the lowest side longitudinal. Similarly, forthe flat part of adjacent bottom plating, any increased thickness for the bilge plating does not have to beextended to the adjacent plate provided that the plate seam is not more than s1/4 beyond the outboardbottom longitudinal. For definition of s1 and s2, see Figure 1.

Figure 1 Bilge plating without longitudinal stiffening

2.2 Side shell plating in aft- and forebody2.2.1 Strengthening for anchor and chain cable contactThe shell plating shall be increased in thickness at the forward end of the bulb and also in areas likely to besubjected to contact with anchors and chain cables during anchor handling. The increased plate thicknessshall be the same as that required for plated stems given in Ch.10 Sec.6 [1.1.1].

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2.2.2 Shell plating connected with stern frameThe net thickness of shell plating connected with the stern frame shall not be less than that obtained, in mm,from the following formula:

In way of the boss and heel plate, the net thickness of shell plating, in mm, shall not be less than:

2.2.3 Heavy shell plates in way of rudder hornHeavy shell plates shall be fitted locally in way of the heavy plate floors in way of the rudder horn. Outboardof the heavy floors, the heavy shell plates may be reduced in thickness.

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SECTION 5 STIFFENERSSymbols


dshr = effective shear depth, in mm, as defined in Ch.3 Sec.7 [1.4.3]ℓbdg = effective bending span, in m, as defined in Ch.3 Sec.7 [1.1.2]ℓshr = effective shear span, in m, as defined in Ch.3 Sec.7 [1.1.3]P = design pressure for the design load set being defined in Sec.2 and calculated at the load calculation

point defined in Ch.3 Sec.7 [3.2], in kN/m2


1 Stiffeners subject to lateral pressure

1.1 General1.1.1 Web platingThe minimum net web thickness, in mm, shall not be taken less than the greatest value calculated for allapplicable design load sets as defined in Sec.2 [2], given by:

where:

fshr = shear force distribution factor as defined in Table 1. For stiffeners with end fixity deviating from theones included in Table 1, with complex load pattern, or being part of a grillage, the requirementsgiven in [1.2] apply.

Table 1 Definition of fshr

For continuous stiffeners with fixed end For non-continuous stiffenerswith simply supported ends

CoefficientHorizontal stiffeners Upper end of

vertical stiffenersLower end of

vertical stiffeners All stiffeners

fshr 0.5 0.4 0.7 0.5

Ct = permissible shear stress coefficient for the acceptance criteria being considered, as defined in Table2

Table 2 Stiffeners, definition of Ct

Acceptance criteria Structural member Ct

AC-I All stiffeners 0.75

AC-II All stiffeners 0.90

AC-III All stiffeners 0.95

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1.1.2 Section modulusThe minimum net section modulus, in cm3, shall not be taken less than the greatest value calculated for allapplicable design load sets as defined in Sec.2 [2.1.3], given by:

where:

fbdg = bending moment factor as defined in Table 5. For stiffeners with end fixity deviating from theones included in Table 5, with complex load pattern, or being part of a grillage, the requirementgiven in [1.2] applies

fm = bending moment ratio between end support and midspan as defined in Table 5fu = factor for unsymmetrical profiles, to be taken as:

= 1.00 for flat bars and symmetrical profiles (T-profiles)= 1.03 for bulb profiles= 1.15 for unsymmetrical profiles (L-profiles)

Cs = permissible bending stress coefficient as defined in Table 3 for the acceptance criteria given inTable 4

Cs-max = coefficient, as defined in Table 4σhg = hull girder bending stress, in N/mm2, as defined in Sec.2 [1.1], calculated at the load calculation

point as defined in Ch.3 Sec.7 [3.2]αs = coefficient, as defined in Table 4βs = coefficient, as defined in Table 4

Table 3 Stiffeners, definition of Cs

Structuralmember

Sign of hullgirder stress, σhg

Lateral pressureacting on Coefficient Cs

Tension (positive) Stiffener side

Compression (negative) Plate side

but not to be taken greater than Cs-max

Tension (positive) Plate side

For continuousstiffeners

Compression (negative) Stiffener side


Tension (positive) Plate side

Compression (negative) Stiffener side


Tension (positive) Stiffener side

For non-continuousstiffeners

Compression (negative) Plate sideCs = Cs-max

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Table 4 Stiffeners, definition of βs, αs and Cs-max

Acceptance criteria Structural member βs αs Cs-max

Longitudinal members 0.95 1.00 0.85AC-I


Longitudinal members 1.10 1.00 0.95AC-II


Longitudinal members 1.20 1.00 1.00AC-III


Table 5 Stiffeners, definition of fbdg and fm

For continuous stiffeners with fixed ends

For continuousstiffeners withone fixed end

and one simplysupported end

For non-continuousstiffeners

with simplysupported endsCoefficient Acceptance

criteria

Horizontal stiffenersand upper end ofvertical stiffeners

Lower endof verticalstiffeners

Horizontal andvertical stiffeners

Horizontal andvertical stiffeners

fbdgAC-I, AC-II,AC-III 12.00 10.00 8.00 8.00

AC-I 2.00 2.33 1.77fm

AC-II, AC-III 1.60 1.86 1.42-

1.1.3 Grouping of stiffenersScantlings of stiffeners based on requirements given in [1.1.1] and [1.1.2] may be decided based on theconcept of grouping designated sequentially placed stiffeners of equal scantlings on a single stiffened panel.The scantling of the group shall be taken as the greater of the following:

— the average of the required scantling of all stiffeners within a group— 90% of the maximum scantling required for any one stiffener within the group

1.1.4 Plate and stiffener of different materialsWhen the minimum specified yield stress of a stiffener exceeds the minimum specified yield stress of theattached plate by more than 35%, the following criterion shall be satisfied:

where:

ReH-S = minimum specified yield stress of the material of the stiffener, in N/mm2

ReH-P = minimum specified yield stress of the material of the attached plate, in N/mm2

σhg = hull girder bending stress, in N/mm2, as defined in Pt.4 Ch.6 Sec.2 [1.1] with |σhg| not to betaken less than 0.4 ReH-P

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Z = net section modulus, in way of face plate/free edge of the stiffener, in cm3

ZP = net section modulus, in way of the attached plate of stiffener, in cm3

αs , βs = coefficients defined in Table 4

1.1.5 Struts connecting stiffenersStruts fitted between stiffeners in a double skin structure are in general not to be considered as effectivesupports for the stiffeners.

The requirements given in[1.1.1] and [1.1.2], however, may be based on reduced bending and shear span asgiven in Ch.3 Sec.7 [1.1.4].

The net sectional area, in cm2, and the net moment of inertia about the weaker axis, in cm4, of strutsconnecting stiffeners shall not be less than the values obtained from the following formulae:

where:

PSR = pressure to be taken as the greater of the following values, in kN/m2:

PSR1 = pressure in way of the strut, in kN/m2, acting on one side, outside the compartment inwhich the strut is located

PSR2 = pressure in way of the strut, in kN/m2, acting on the opposite side, outside thecompartment in which the strut is located

PSR3 = internal pressure at mid-span of the strut, in kN/m2, in the compartment in which thestrut is located

ℓSR = length of the strut, in mAASR = actual net sectional area of the strut, in cm2

1.2 Beam analysis1.2.1 ApplicationThe maximum normal bending stress, σb, and shear stress, τ, in a stiffener using net properties with reducedend fixity, variable load or being part of grillage shall be determined by direct calculations taking intoaccount:

— the distribution of static and dynamic pressures and forces, if any— the number and position of intermediate supports, e.g. decks, girders, etc— the condition of fixity at the ends of the stiffener and at intermediate supports— the geometrical characteristics of the stiffener on the intermediate spans— the effective breadth, beff, for yield check as given in Ch.3 Sec.7 [1.3]

1.2.2 Stress criteriaThe calculated stress, in N/mm2, shall comply with the following criteria:

— τ ≤ CtτeH— σb ≤ CsReH

where:

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Ct = permissible shear stress coefficient for the design load set being considered, as defined in Table 2Cs = permissible bending stress coefficient as defined in Table 3 for the design load set being consideredτ = average shear stress in member, in N/mm2, at the considered position, taken as:

Q = shear force, in kN, at the considered positionAshr = net shear area, in cm2, at the considered positionσb = bending normal stress, in N/mm2, at the considered position, taken as:

fu = factor for unsymmetrical profiles to be taken as given in [1.1.2]M = bending moment, in kNm, at the considered positionZ = net section modulus, in cm3, based on effective breadth according to Ch.3 Sec.7 [1.3] at the

considered position

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SECTION 6 PRIMARY SUPPORTING MEMBERS AND PILLARSSymbols


P = design pressure for the design load set being considered as defined in Sec.2 and calculated at theload calculation point as defined in Ch.3 Sec.7 [4.1], in kN/m2


ℓbdg = effective bending span, as defined in Ch.3 Sec.7 [1.1.6], in mℓshr = effective shear span, as defined in Ch.3 Sec.7 [1.1.7], in m

1 General

1.1 Application

1.1.1 The requirements for this section apply to PSM (primary supporting members) subjected to lateralpressure and concentrated loads and pillars subjected to axial loads. The yielding and where relevantbuckling checkshall be carried out for such members subjected to specific loads.

1.1.2 The requirements for this article apply unless verification by means of FE analysis has been carried out.The section modulus requirement given in [2.1.1] is not applicable for double skin primary supportingmembers and to longitudinal primary supporting members with hull girder stresses exceeding 0.15 ReH. Suchmembers shall be assessed in accordance with [2.2] or by FE analysis.

2 Primary supporting members beam analysis

2.1 Scantling requirements2.1.1 Net section modulusThe net section modulus, in cm3, of primary supporting members subjected to lateral pressureshall not betaken less than the greatest value for all applicable design load sets defined inSec.2 [2], given by:

where:

fbdg = bending moment distribution factor, as given in Table 1Cs = permissible stress coefficient to be taken as:

Cs = 0.70 for AC-ICs = 0.85 for AC-II and AC-III

2.1.2 Net shear areaThe net shear area, in cm2, of primary supporting members subjected to lateral pressure shall not be takenless than the greatest value for all applicable design load sets defined in Sec.2 [2], given by:

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where:

fshr = shear force distribution factor, as given in Table 1Ct = permissible shear stress coefficient to be taken as:

Ct = 0.70 for AC-ICt = 0.85 for AC-II and AC-III

Table 1 Definition of bending moment and shear force factors, fbdg and fshr

Load and boundary conditionBending moment and shear forcedistribution factors (based on loadat mid span, where load varies)

Position 1 2 3

Load model1

Support2

Field3

Supportfbdg1

fshr1

fbdg2

-fbdg3

fshr3

A

12.00.50

24.0-

12.00.50

B

-0.38

14.2-

8.00.63

C

-0.50

8.0-

-0.50

D

15.00.30

23.3-

10.00.70

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Load and boundary conditionBending moment and shear forcedistribution factors (based on loadat mid span, where load varies)

Position 1 2 3

Load model1

Support2

Field3

Supportfbdg1

fshr1

fbdg2

-fbdg3

fshr3

E

-0.20

16.8-

7.50.80

F

--

--

2.01.0

Note 1: The bending moment distribution factor, fbdg for the support positions is applicable for a distance of 0.2ℓbdg fromthe end of the effective bending span of the primary supporting member.

Note 2: The shear force distribution factor, fshr for the support positions is applicable for a distance of 0.2 ℓshr from theend of the effective shear span of the primary supporting member.

Note 3: Application of fbdg and fshr:

The section modulus requirement within 0.2ℓbdg from the end of the effective span shall be determined using theapplicable fbdg1 and fbdg3, however thefbdgis not to be taken greater than 12

The section modulus of mid-span area shall be determined using fbdg = 24, or fbdg2 from the table if lesser.

The shear area requirement for end connections within 0.2ℓshr from the end of the effective span shall be determinedusing fshr = 0.5 or the applicable fshr1 or fshr3, whichever is greater.

For models A through F, the value of fshr may be gradually reduced outside of 0.2ℓshr towards 0.5 fshr at mid-span, wherefshr is the greater value of fshr1 and fshr3.

2.1.3 Maximum flange area of primary supporting memberThe effective flange area of primary supporting member shall satisfy the following:

where:

ReH,p = minimum specified yield stress of the material of the plate, in N/mm2

ReH,f = minimum specified yield stress of the material of the flange, in N/mm2

2.2 Advanced calculation methods2.2.1 ApplicationWhere complex grillage structures are employed or cross ties are fitted in side shell primary supportingmembers, the scantlings shall be determined by direct calculation taking into account:

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— the distribution of still water and wave pressure and forces, if any— the number and position of intermediate supports, e.g. decks, girders, etc— the condition of fixity at the ends of the primary supporting members and at intermediate supports— the geometrical characteristics of the primary supporting members on the intermediate spans— the effective breadth, beff, for yield check as given in Ch.3 Sec.7 [1.3]

Modelling methods and techniques for a beam analysis are given in the Society's document DNVGL-CG-0127,Finite element analysis, Sec.5.

2.2.2 Yield criteria for beam analysisThe calculated stresses, in N/mm2, shall comply with the following criteria:

— σ ≤ Cs1ReH— σb ≤ Cs2ReH

— τ ≤ CtτeH

where:

τ = average shear stress in member, in N/mm2, at the considered position, taken as:

Q = shear force, in kN, at the considered positionAshr-n50 = net shear area, in cm2, at the considered positionσ = combined stress of normal stress including hull girder stress, σhg, and bending stress in

member, in N/mm2, at the considered positionσb = bending normal stress, in N/mm2, at the considered position, taken as:

M = bending moment, in kNm, at the considered positionZn50 = net section modulus, in cm3, based on effective breadth according to Ch.3 Sec.7 [1.3] at the

considered position

Table 2 Beam analysis of primary supporting members, definition of Cs1,Cs2 and Ct

Acceptance criteria Structural member Cs1 Cs2 Ct

AC-I 0.85 0.70 0.70

AC-II, AC-IIIAll primary supporting members

0.95 0.85 0.85

2.2.3 Buckling criteria for beam analysisBuckling strength shall be considered for panels with high in-plane stresses e.g. bottom/deck in midshiparea, with acceptance criteria given in Ch.8 Sec.4. For buckling assessment fully effective plate flange maybe used.

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The normal stresses including hull girder stress, σhg, and the shear stresses taken from the strengthassessment to be applied for buckling capacity calculation of plate panels, as given in Ch.8 Sec.4, shall becorrected as given in the Society's document DNVGL-CG-0128, Buckling analysis, [3.2.2.7].

2.2.4 Yield and buckling criteria for finite element analysisWhen finite element analysis is used for analysis of PSM then all significant stress components shall beconsidered, to a similar extent as for partial ship finite element models described in Ch.7 Sec.3. The strengthshall satisfy the yield criteria given in Ch.7 Sec.3 and buckling criteria given in Ch.8 Sec.4.

3 Pillars

3.1 Pillars subjected to compressive axial load3.1.1 CriteriaThe maximum applied compressive axial load on a pillar, Fpill, in kN, shall be taken as the greatest valuecalculated for all applicable design load sets defined in Sec.2 [2], and is given by the following formula:

The buckling check of the pillar shall be performed according to Ch.8 Sec.4 [4.1], with σav in N/mm2 givenby:

where:

ba-sup = mean breadth of area supported, in mℓa-sup = mean length of area supported, in mFpill-upr = axial load from pillar including axial load from pillars above, in kN, if anyApill-n50 = net cross section area of the pillar, in cm2

3.2 Pillars subject to tensile axial loadThe calculated stresses in pillars inclusive end connections subjected to tensile axial load, shallsatisfy thefollowing criteria:

where:σ = normal stress in N/mm2, for the minimum cross section inclusive end connectionsτ = shear stress in N/mm2 the bracket/gusset end connectionsCs, = permissible normal stress coefficient as given in [2.1.1]Ct = permissible shear stress coefficient as given in [2.1.2]

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SECTION 7 INTERSECTION OF STIFFENERS AND PSMSymbolsFor symbols not defined in this section, refer to Ch.1 Sec.4.

1 Stiffener connections

1.1 Arrangement of cut-outs

1.1.1 Cut-outs for the passage of stiffeners through the web of primary supporting members, and the relatedcollaring arrangements, shall be designed to minimise stress concentrations around the perimeter of theopening and on the attached web stiffeners.

1.1.2 The total depth of cut-outs without lug or collar plate shall be not greater than 40% of the depth ofthe primary supporting member. A larger depth of cut-outs may be accepted given that shear strength andbuckling capacity are sufficient.

1.1.3 Cut-outs in way of cross tie ends and floors under bulkhead stools or in high stress areas shall be fittedwith lug plates welded to the attached plating, see Figure 1.

Figure 1 Lug plates welded to the attached plating

1.1.4 Lug plates shall be fitted in cut-outs where required for compliance with the requirements givenin[1.2], and in areas of high stress concentrations, e.g. in way of primary supporting member toes. SeeFigure 2 for typical lug arrangements.

1.1.5 At connection to shell envelope longitudinals below the scantling draught, Tsc and at connectionto inner bottom longitudinals, a soft heel shall be provided in way of the heel of the primary supportingmember web stiffeners when the calculated direct stress, σw, in the primary supporting member web stiffeneraccording to [1.2] exceeds 80% of the permissible values. The soft heel shall have a keyhole, similar to thatshown in item (c) in Figure 3.A soft heel is not required at the intersection with watertight bulkheads and primary supporting members,where a back bracket is fitted or where the primary supporting member web is welded to the stiffener faceplate.

1.1.6 In general, cut-outs shall have rounded corners and the corner radii, R, shall be as large as practicable,with a minimum of 20% of the breadth, b, of the cut-out or 25 mm, whichever is greater. The corner radii, R,do not need to be greater than 50 mm, see Figure 1. Consideration shall be given to other cut-out shapes onthe basis of maintaining equivalent strength and minimising stress concentration.

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Figure 2 Symmetric and asymmetric cut-outs

The details shown in this figure are only used to illustrate symbols and definitions and are not intended torepresent design guidance.

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Figure 3 Primary supporting member web stiffener details

Symbols shown in Figure 3 shall be taken as:

tws , tws1, tws2 = net thickness of the primary supporting member web stiffener/backing bracket, in mmdw , dw1, dw2 = minimum depth of the primary supporting member web stiffener/backing bracket, in

mm

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dwc , dwc1, dwc2 = length of connection between the primary supporting member web stiffener/backingbracket and the stiffener, in mm.

Note:Except where specific dimensions are noted for the details of the keyhole in way of the soft heel, the details shown in this figure areonly used to illustrate symbols and definitions and are not intended to represent design guidance or recommendations.

---e-n-d---of---n-o-t-e---

1.2 Connection of stiffeners to PSM1.2.1 ApplicationIn lieu of simplified method as given in [1.3], calculations may be performed according to [1.2] irrespectiveof ship’s length.

1.2.2 GeneralFor connection of stiffeners to PSM in case of lateral pressure other than bottom slamming and bow impactloads, [1.2.3] and [1.2.4] shall be applied. In case of bottom slamming or bow impact loads, Ch.10 Sec.2[3.2.2] and Ch.10 Sec.1 [3.2.3] shall be applied respectively.The cross sectional areas of the connections shall be determined from the proportion of load transmittedthrough each component in association with its appropriate permissible stress.

1.2.3 The load, in kN, transmitted through the shear connection shall be taken as follows.

— If the web stiffener is connected to the intersecting stiffener:

— If the web stiffener is not connected to the intersecting stiffener:

W1 = W

where:

W = total load, in kN, transmitted through the stiffener connection to the PSM taken equal to:

P1, P2 = design pressure applied on the stiffener for the design load set being considered, in kN/m2, oneach side of the considered connection

S1, S2 = spacing between the considered and the adjacent PSM on each side of the consideredconnection, in m

s1, s2 = spacing of the stiffener, in mm, on each side of the considered connectionαa = panel aspect ratio, not to be taken greater than 0.25

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A1 = effective net shear area, in cm2, of the connection, to be taken equal to:A1 = A1d + A1c

In case of a slit type slot connections area, A1, is given by:A1 = 2 A1d

In case of a typical double lug or collar plate connection area, A1, is given by:A1 = 2 A1c

A1d = net shear connection area, in cm2, excluding lug or collar plate, as given by:A1d = ℓd tw 10-2

ℓd = length of direct connection between stiffener and PSM web, in mmtw = net web thickness of the primary supporting member, in mmA1c = net shear connection area, in cm2, with lug or collar plate, given by:

A1c = f1ℓc tc 10-2

ℓc = length of connection between lug or collar plate and PSM, in mmtc = net thickness of lug or collar plate shall not be less than 75% of the web plate thickness and

need not to be taken greater than the net thickness of the adjacent PSM web, in mmf1 = shear stiffness coefficient, taken as:

f1 = 1.0, for stiffeners of symmetrical cross sectionf1 = 140/w, not to be taken greater than 1.0, for stiffeners of asymmetrical cross section

w = width of the cut-out for an asymmetrical stiffener, measured from the cut-out side of thestiffener web, in mm, as indicated in Figure 2

Aw = effective net cross sectional area, in cm2, of the PSM web stiffener in way of the connectionincluding backing bracket where fitted, as shown in Figure 3. If the PSM web stiffenerincorporates a soft heel ending or soft heel and soft toe ending, Awshall be measured at thethroat of the connection, as shown in Figure 3

fc = collar load factor taken equal to:For intersecting stiffeners of symmetrical cross section:

fc = 1.85 for Aw ≤ 14

fc = 1.85 –0.0441(Aw – 14)

for 14 < Aw ≤ 31

fc = 1.1 – 0.013(Aw– 31)

for 31 < Aw ≤ 58

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fc = 0.75 for Aw > 58

For intersecting stiffeners of asymmetrical cross section:

ℓs = connection length equal to:For a single lug or collar plate connection to the PSM:ℓs = ℓcFor a single sided direct connection to the PSM:ℓs = ℓdIn the case of a lug or collar plus a direct connection:ℓs = 0.5 (ℓc + ℓd)

1.2.4 The load, in kN, transmitted through the PSM web stiffener shall be taken as:

— if the web stiffener is connected to the intersecting stiffener:

— if the web stiffener is not connected to the intersecting stiffener:W2 = 0

The values of Aw, Awc and A1shall be such that the calculated stresses satisfy the following criteria:

— for the connection to the PSM web stiffener not in way of the weld: σw ≤ σperm— for the connection to the PSM web stiffener in way of the weld: σwc ≤ σperm— for the shear connection to the PSM web: τw ≤ τpermwhere:

W = load, in kN, as defined in [1.2.3]fc = collar load factor as defined in [1.2.3]αa = panel aspect ratio, as defined in [1.2.3]A1 = effective net shear area, in cm2, as defined in [1.2.3]Aw = effective net cross sectional area, in cm2, as defined in [1.2.3]σw = direct stress, in N/mm2, in the PSM web stiffener at the minimum bracket area away from the

weld connection:

σwc = direct stress, in N/mm2, in the PSM web stiffener in way of the weld connection:

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τw = shear stress, in N/mm2, in the shear connection to the PSM web:

Awc = effective net area, in cm2, of the PSM web stiffener in way of the weld as shown in Figure 3σperm = permissible nominal stress, in N/mm2, as given in Table 1τperm = permissible shear stress, in N/mm2, as given in Table 1

Table 1 Permissible stresses for connection between stiffeners and PSMs

Item Direct stress, σperm, in N/mm2 (1)Shear stress, τperm, in N/mm2 (1)

Acceptance criteria AC-I AC-II AC-III AC-I AC-II AC-III

PSM web stiffener 0.83 ReH(2) ReH ReH - - -

PSM web stiffener to intersecting stiffenerin way of weld connection:

— Double continuous fillet 0.58 ReH(3) 0.7 ReH

(3) 0.75 ReH(3) - - -

— Partial penetration weld 0.83 ReH(2) (3) ReH

(2) ReH(2) - - -

PSM stiffener to intersecting stiffener inway of lapped welding 0.5 ReH 0.6 ReH 0.65 ReH - - -

Shear connection including lugs or collarplates:

— Single sided connection - - - 0.71 τeH 0.85 τeH 0.90 τeH

— Double sided connection - - - 0.83 τeH τeH τeH

1) Acceptance criteria for the design load sets are given in Sec.2 Table 1.2) The root face shall not be greater than one third of the gross thickness of the PSM stiffener.3) Permissible stresses may be increased by 5 percent where a soft heel is provided in way of the heel of the PSM web

stiffener.

1.2.5 Where a backing bracket is fitted in addition to the PSM web stiffener, it shall be aligned with the webstiffener. The arm length of the backing bracket shall not be less than the depth of the web stiffener. The netcross sectional area through the throat of the bracket shall be included in the calculation of Aw as shown inFigure 3.

1.2.6 Lapped connections of PSM web stiffeners or tripping brackets to stiffeners are not permitted within 0.4L for vessels with single deck and with length L of 150 m or above.

1.2.7 Where built-up stiffeners have their flange welded to the side of the web, a double sided arrangementof web stiffener connection to the PSM shall be fitted. This may be achieved by fitting backing brackets

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1.2.8 Where the web stiffener of the PSM is parallel to the web of the intersecting stiffener, but notconnected to it, the offset PSM web stiffener shall be located in close proximity to the stiffener as shown inFigure 4. The ends of the offset web stiffeners shall be suitably tapered and softened.Locations where the web stiffener of the PSM are not connected to the intersecting stiffeners as well as thedetail arrangements shall be specially considered on the basis of their ability to transmit load with equivalenteffectiveness to that of [1.2.3] through [1.2.7]. Details of calculations made and/or testing procedures andresults shall be submitted.

Figure 4 Offset PSM web stiffeners

1.2.9 Size of weldsThe size of the fillet welds for connections between stiffeners and PSM shall be calculated according to Ch.13Sec.1 [2.5.6].

1.3 Simplified calculation of connection of stiffeners to PSM1.3.1 ApplicationThe simplified calculation method given in this sub-section is applicable for ships of length less than 90meters.

1.3.2 GeneralFor connection of stiffeners to PSM in case of lateral pressure other than bottom slamming and bow impactloads, [1.3.3]shall be applied. In case of bottom slamming or bow impact loads, [1.3.4]shall be applied.The cross sectional areas of the connections shall be determined from the proportion of load transmittedthrough each component in association with its appropriate permissible stress.

1.3.3 The total load, in kN, transmitted through the connection to the PSM shall be taken equal to:

where:

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P = design pressure applied on the stiffener for the design load set being considered, in kN/m2. Forstiffeners having different spans on each side of the PSM (i.e. different PSM spacing, S1 and S2),and/or subject to different pressure, P1 and P2, at each side of the PSM, the average load for thetwo sides shall be applied to estimate the reaction force, e.g. vertical stiffeners at transversebulkhead, taken as:

S = average spacing of the considered PSM crossed by the stiffener, in m. For stiffeners havingdifferent spans on each side of PSM (i.e. different PSM spacing, S1 and S2), the average span istaken as:

A1 = effective net shear area, in cm2, of the connection to the PSM web, to be taken equal to the sumof the single or double sided connection:

Aw = effective net cross sectional area, in cm2, of the PSM web stiffener in way of the connectionincluding backing bracket where fitted, as shown in Figure 3

W1 = the load transmitted through the shear connection, in kN, see Table 2W2 = the load transmitted through the PSM web stiffener, in kN, see Table 2σperm = permissible nominal stress , in N/mm2, as given in Table 2τperm = permissible shear stress , in N/mm2, as given in Table 2

Table 2 Load distribution and permissible stresses

Permissible stresses (1) Load distribution

Load

AC-I AC-II, AC-IIIIntersecting stiffenersof symmetrical crosssection, e.g T-profile

Intersecting stiffenersof asymmetrical crosssection, e.g. L-profile

No webstiffeners

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W1 τperm = 0.64 τeH - τperm = 0.76 τReH 0.4 W 0.5 W W

W2 σperm = 0.52 ReH - σperm = 0.63 ReH 0.6 W 0.5 W 0

1) Acceptance criteria for the design load sets are given in Sec.2 Table 2

1.3.4 Size of weldsThe size of the fillet welds for connections between stiffeners and PSM shall be calculated according to Ch.13Sec.1 [2.5.5].

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SECTION 8 SUPERSTRUCTURE, DECKHOUSE AND COMPANIONWAYSSymbols


αp = correction factor for the panel aspect ratio to be taken as follows but not to be taken greater than1.0:

P = design pressure for the design load set being defined below, and calculated at the load calculationpoint defined in Ch.3 Sec.7 [3.2], in kN/m2

PD = lateral pressure for exposed decks, in kN/m2, as defined in Ch.4 Sec.5 [3.2]Pdl = lateral pressure due to distributed load, in kN/m2, as defined in Ch.4 Sec.6 and Ch.4 Sec.5 [2.3]PSI = lateral pressure for superstructure side, in kN/m2, as defined in Ch.4 Sec.5 [3.3]PA = external pressure for end bulkheads of superstructure and deckhouse walls, in kN/m2 according to

Ch.4 Sec.5 [3.4.1]ℓbdg = effective bending span, in m, as defined in Ch.3 Sec.7 [1.1]ℓshr = effective shear span, in m, as defined in Ch.3 Sec.7 [1.1]dshr = effective shear depth, in mm, as defined in Ch.3 Sec.7 [1.4.3]

1 General

1.1 Application

1.1.1 The requirements for this section are applicable to superstructures, deckhouses and companionways.Applicable rule requirements and design pressures and forces for plate, stiffener and primary supportingmembers are given in Table 1 for the different design load sets.

Table 1 Design load sets

Structural member Designload set

Designload

scenarioLoad component4) Applicable rule

requirementsAcceptance

criteria


Side bulkhead Max(Pw;PSI)

Exposed decksSEA-1 2

PD

Full loadcondition

UDL-12) 2Pdl-s+Pdl-d

FU-s+FU-d

AC-IINormalballast

condition3)

Longitudinalstrengthmembers

Exposeddecks and

non-exposeddecks with

distributed load UDL-22) 1Pdl-s

FU-s

Sec.4, Sec.5and Sec.6

AC-I -

Front and aftbulkhead PA

Others

Side bulkhead

SEA-1 2

PA

Sec.8 - 1) -

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Structural member Designload set

Designload

scenarioLoad component4) Applicable rule

requirementsAcceptance

criteria


Exposed decks PD

UDL-12) 2

Pdl-s+Pdl-d

FU-s+FU-dAC-II

Normalballast

condition3)

Exposed decksand non-exposed decksand platformswith distributedload

UDL-22) 1

Pdl-s

FU-s

Sec.4, Sec.5and Sec.6-

AC-I -

1) The requirements are based on IACS UR S3.2) Distributed or concentrated loads only. Need not to be combined with simultaneously occurring green sea pressure.3) For cargo loads, draught, GM and kr values may be based on actual cargo conditions in the loading manual.4) Local loads:

PW = wave pressure as given in Ch.4 Sec.5 [1.3]PD = external dynamic design pressure for exposed decks and wheelhouse top due to green sea loading as

given in Ch.4 Sec.5 [2.2] and Ch.4 Sec.5 [3.2], respectivelyPA = design pressure for aft- and forward external bulkheads of superstructure and deckhouse walls as

given in Ch.4 Sec.5 [3.4]PSI = external design pressure for external side of superstructure as given in Ch.4 Sec.5 [3.3]Pdl = pressure due to distributed deck load given in Ch.4 Sec.5 [2.3.1] or Ch.4 Sec.6 [2.2]FU = force on exposed and non-exposed decks and platforms due to unit loads as given in Ch.4 Sec.5

[2.3.2]

2 Structural arrangement

2.1 Structural continuity2.1.1 Bulkheads and sidesThe aft, front and side bulkheads shall be effectively supported by under deck structures such as bulkheads,girders and pillars.Sides and main longitudinal and transverse bulkheads shall be in line in the various tiers of deckhouses.Where such arrangement in line is not possible, other effective support shall be provided.Sufficient transverse strength shall be provided by means of transverse bulkheads or girder structures.

2.1.2 Ends of superstructureAt the end of superstructures, which are in line with the ship sides, the side plating of poop and bridge shallextend beyond the ends of the superstructure, and shall be gradually reduced in height down to the sheerstrake. The transition shall be smooth and without local discontinuities. A substantial stiffener shall be fittedat the upper edge of plating, which extends beyond the superstructure. The plating shall also be additionallystiffened.

2.1.3 OpeningsArrangements shall be made to minimise the effect of structural discontinuities. All openings cut in the sidesshall be framed and have well-rounded corners. Horizontal stiffeners shall be fitted at the upper and loweredge of large openings for windows. Continuous coamings or girders shall be fitted below and above doorsand similar openings, and shall extend well beyond the openings.

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2.1.4 Deckhouse side and cornersDeck girders shall be fitted below long deckhouses in line with deckhouse sides. The girders shall extendthree frame spaces forward and aft of the deckhouse ends. Girders shall be stiffened at the lower edge.

Guidance note:Expansions joints should be provided for long deckhouse sides, not intended to take part in the global hull girder strength.

---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e---

At the corners where the deckhouse is attached to the strength deck, attention shall be given to thearrangements to transmit load into the under deck supporting structure. The connection area betweendeckhouse corners and deck plating shall be increased locally.

2.1.5 ScallopsDeck beams under front and aft ends of deckhouses shall not be scalloped for a distance of 0.5 m from eachside of the deckhouse corners.

2.2 End connections2.2.1 Deck stiffenersTransverse beams shall be connected to side frames by brackets according to Ch.3 Sec.6 [2.2]. Beamscrossing longitudinal walls and girders may be attached to the stiffeners of longitudinal walls and the webs ofgirders respectively by welding without brackets.

2.2.2 Longitudinal and transverse deck girdersFace plates shall be stiffened by tripping brackets according to Ch.3 Sec.6 [3.3].

2.2.3 End connections of superstructure framesVertical frames shall be welded to the main frames below, or to the deck under provision of a sufficientsupporting structure.

2.3 Local reinforcement on bulkheads

2.3.1 Local reinforcement shall be provided in way of large openings and areas supporting life savingappliances or high loads from other equipment, fittings, etc.

2.4 Exposed sides of superstructure sidesExposed sides of superstructures, when flush with ship side, inclusive their supporting structure are tocomply with the bow impact requirements given in Ch.10 Sec.1 [4.1], if applicable.

3 Scantlings

3.1 Minimum thicknesses and minimum section modulus3.1.1 Minimum thickness of decksThe minimum net thickness of deck plating, in mm, shall not be less than 4.5 mm in general.For the first tier of weather deck in superstructure or deckhouse in vessels with single continuous deck whenmore than 50% of 0.4L amidships is covered, the minimum net thickness of deck plating, in mm, shall not beless than 4.5+0.01L2.If the decks of superstructure and deckhouses contribute to hull girder longitudinal strength, the minimumnet thickness of plating shall not be less than the requirement given in Sec.3 Table 1.

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3.1.2 Minimum thickness of end bulkheadsThe minimum net thickness of plate for end bulkheads, i.e. front, aft and side, in mm, shall not be less than;t = 4.0 + 0.01L2 for first tier above freeboard deckt = 3.0 + 0.01L2 for upper tiers, but not to be less than 4.0 mm

3.1.3 Minimum thickness of protected casings and internal wallsTThe minimum net thickness of plate for the protected casing and internal wall, in mm, shall not be lessthan;t = 5.0 mm for structure in the cargo areat = 4.5 mm for structure in way of accommodation

3.1.4 Minimum section modulus of stiffenersThe minimum net section modulus, in cm3, of stiffeners used for deckhouse and superstructureshall not beless than:

3.2 PlatingThe net thickness, in mm, shall not be less than:

3.3 StiffenersThe net section modulus, in cm3, of stiffener is not be taken less than:

3.4 Primary supporting members3.4.1 Net section modulusThe minimum net section modulus, in cm3, of primary supporting members shall not be taken less than:

fbdg = bending moment factor as given in Sec.6 Table 1

3.4.2 Net shear areaThe net shear area, in cm2, of primary supporting members subjected to lateral pressure shall not be takenless than:

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fshr = shear force distribution factor as given in Sec.6 Table 1

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3.4.3 Alternative grillage analysis for primary supporting members

Where arrangements of deck girders and transverses are such that these members act as a grillagestructure, additional analysis may be carried out with a structural model based on net scantlings. Theresulting stresses shall not exceed the following permissible bending, shear and equivalent stresses, in N/mm2, taken as:

σb = 0.9 ReHτ = 0.9 τeHσvm = ReH

3.5 Aluminium deckhouse or superstructure3.5.1 ScantlingsScantlings of plates, stiffeners and primary supporting members shall be in accordance with [3.1] to [3.5].Minimum thickness and slenderness will be considered on a case-by-case basis.

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