COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No. 1
January 2009

Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 1 OF 171

RULE CHANGE NOTICE NO.1

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table of Contents
Rule Change Notice No.1-1 (Hull Girder Strength) …………………...…………………3
Technical Background for Rule Change Notice No.1-1(Hull Girder Strength)…………19
Rule Change Notice No.1-2 (Hatch Covers) ………………………………………....…31
Technical Background for Rule Change Notice No.1-2 (Hatch Covers) …………..…...35
Rule Change Notice No.1-3 (Steel Coil) …………………………………….…….……41
Technical Background for Rule Change Notice No.1-3 (Steel Coil) ……..…………….51
Rule Change Notice No.1-4 (Minimum Scantling, Side Frame and Grab) ………..……71
Technical Background for Rule Change Notice No.1-4(Minimum Scantling, Side Frame and Grab) ………....79
Rule Change Notice No.1-5 (Direct Strength Analysis) ………………………..……….83
Technical Background for Rule Change Notice No.1-5 (Direct Strength Analysis) ...….89
Rule Change Notice No.1-6 (Fatigue Check for Longitudinals) …...………………...…97
Technical Background for Rule Change Notice No.1-6(Fatigue Check for Longitudinals) ……...…...………119
Rule Change Notice No.1-7 (Corrosion Additions) …...……………………………….133
Technical Background for Rule Change Notice No.1-7 (Corrosion Additions) …....….139
Rule Change Notice No.1-8 (Corrugated Bulkhead) ……...………………………..….143
Technical Background for Rule Change Notice No.1-8 (Corrugated Bulkhead) ......….163
Rule Change Notice No.1-9 (Main Engine Foundation) ……………....………………167
Technical Background for Rule Change Notice No.1-9 (Main Engine Foundation) … 169

PAGE 2 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-1

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-1(Hull Girder Strength)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 3 OF 171

RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-1.

CHAPTER 5 HULL GIRDER STRENGTH
Section 1 YIELDING CHECK

2. Hull girder stresses
2.2 Shear stresses
2.2.2 Simplified calculation of shear stresses induced by vertical shear forces
The shear stresses induced by the vertical shear forces in the calculation point are obtained, in N/mm2, from thefollowing formula:τ 1 = (QSW + QWV − εΔQC )

S
δ
IY t

where:t: Minimum net thickness, in mm, of side and inner side plating, as applicable according to Tab 1

δ: Shear distribution coefficient defined in Tab 1

ε = sgn (QSW )ΔQC: Shear force correction (see Fig 2) at the section considered. The shear force correction is to beconsidered independently forward and aft of the transverse bulkhead for the hold considered. , which
The shear force correction takes into account, when applicable, the portion of loads transmitted by the
double bottom girders to the transverse bulkheads:• for ships with any non-homogeneous loading conditions, such as alternate hold loading conditions
and heavy ballast conditions carrying ballast in hold(s):ΔQC = αM
M
− ρTLC ΔQC = α− ρTLC ,mh for each non-homogeneous loading condition
BH l H
BH l H• for other ships and homogeneous loading conditions:

ΔQC = 0lb0

ϕ = 1.38 + 1.55 0 , to be taken not greater than 3.7α=g

l 0 b0l
2 +ϕ 0b0

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COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-1

l0 , b0 : Length and breadth, respectively, in m, of the flat portion of the double bottom in way of the holdconsidered; b0 is to be measured on the hull transverse section at the middle of the holdlH

: Length, in m, of the hold considered, measured between the middle of the transverse corrugatedbulkheads depth

BH: Ship’s breadth, in m, measured at the level of inner bottom on the hull transverse section at the middleof the hold consideredM: Total mass of cargo, in t, in the hold of the section considered Mass, in t, in the considered section.
• Adjacent cargo hold is loaded in a non homogeneous loading condition for the condition underconsideration
M is to include the total mass in the hold and the mass of water ballast in double bottom tank,bounded by side girders in way of hopper tank plating or longitudinal bulkhead.
• Other cases
M is the total mass in the hold.

TLC TLC,mh : Draught, in m, measured vertically on the hull transverse section at the middle of the holdconsidered, from the moulded baseline to the waterline in the loading condition considered.

Bulkhead

Bulkhead

ΔQC ΔQC _ F

Full hold

Empty holdCorrected
shear force

Bulkhead

ΔQC _ E ΔQC=ραTLC

Shear force obtained as
specified in Ch 4, Sec 3

ΔQC _ F : shear force correction for the full hold
ΔQC _ E : shear force correction for the empty hold
Figure 2: Shear force correction ΔQC

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RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 1: Shear stresses induced by vertical shear forces
Ship typology

Locationt, in mmδSingle side ship

Sides

tS

0,5

Double side ship

Sides

tS

0.5(1 − φ )Inner sides

tIS

0.5φ

where:
tS, tIS : Minimum net thicknesses, in mm, of side and inner side, respectivelytSM, tISM : Mean net thicknesses, in mm, over all the strakes of side and inner side , respectively. They are calculatedas Σ(li ti) / Σli, where li and ti are the length, in m, and the net thickness, in mm, of the ith strake of sideand inner side.
t: Coefficient taken equal to: φ = 0.275 + 0.25 ISM
t SM

φ2.2.3 Shear stresses in flooded conditions of BC-A or BC-B ships
This requirement applies to BC-A or BC-B ships, in addition to [2.2.1] and [2.2.2].
The shear stresses, in the flooded conditions specified in Ch 4, Sec 3, are to be obtained at the calculation any
point, in N/mm2, from the following formula:τ 1 = (QSW , F + QWV , F − εΔQC )

S
δ
ΙY t

ε = sgn (Q SW ,F )ΔQC

: Shear force correction, to be calculated according to [2.2.2],where the mass M is to include the massof the ingressed water in the hold considered is to be added to M and where the draught TLC TLC,mh is tobe measured up to the equilibrium waterline.

t: Net thickness, in mm, of the side plating.

5. Permissible still water bending moment and shear force
5.1 Permissible still water bending moment and shear force stresses
5.1.3 Permissible still water shear force - Simplified calculation

Where the shear stresses are obtained through the simplified procedure in [2.2.2], the permissible positive or
negative still water shear force in intact condition at any hull transverse section is obtained, in kN, from thefollowing formula:⎛ 120 Ι Y t⎞
QP = ε ⎜+ ΔQC ⎟ − QWV
δ
k
S
⎝
⎠

where:

ε = sgn (QSW )δ: Shear distribution coefficient defined in Tab 1

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COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-1

t: Minimum net thickness, in mm, of side and inner side plating, as applicable according to Tab 1

ΔQC: Shear force corrections defined in [2.2.2], to be considered independently forward and aft of thetransverse bulkhead.

A lower value of the permissible still water shear force may be considered, if requested by the Shipbuilder.

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RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERSAppendix 1 - HULL GIRDER ULTIMATE STRENGTH

Symbols

For symbols not defined in this Appendix, refer to Ch 1, Sec 4.
IY: Moment of inertia, in m4, of the hull transverse section around its horizontal neutral axis, to be
calculated according to Ch 5, Sec 1, [1.5.1]

ZAB, ZAD : Section moduli, in m3, at bottom and deck, respectively, defined in Ch 5, Sec 1, [1.4.2].
ReHs: Minimum yield stress, in N/mm2, of the material of the considered stiffener.

ReHp: Minimum yield stress, in N/mm2, of the material of the considered plate.

As: Net sectional area, in cm2, of stiffener, without attached plating

Ap: Net sectional area, in cm2, of attached plating

2. Criteria for the calculation of the curve M-χ
2.1 Simplified method based on a incremental-iterative approach
2.1.1 Procedure
The curve M-χ is to be obtained by means of an incremental-iterative approach, summarised in the flow chart in

Fig 1.
In this approach, the ultimate hull girder bending moment capacity MU is defined as the peak value of the curvewith vertical bending moment M versus the curvature χ of the ship cross section as shown in Fig 1. The curve is
to be obtained through an incremental-iterative approach.
Each step of the incremental procedure is represented by the calculation of the bending moment Mi which acts on
the hull transverse section as the effect of an imposed curvature χi.
For each step, the value χi is to be obtained by summing an increment of curvature Δχ to the value relevant to theprevious step χi-1.This increment of curvature corresponds to an increment of the rotation angle of the hull girdertransverse section around its horizontal neutral axis.
This rotation increment induces axial strains ε in each hull structural element, whose value depends on theposition of the element. In hogging condition, the structural elements above the neutral axis are lengthened,
while the elements below the neutral axis are shortened. Vice-versa in sagging condition.
The stress σ induced in each structural element by the strain ε is to be obtained from the load-end shortening
curve σ-ε of the element, which takes into account the behaviour of the element in the non-linear elasto-plastic
domain.
The distribution of the stresses induced in all the elements composing the hull transverse section determines, foreach step, a variation of the neutral axis position, since the relationship σ-ε is non-linear. The new position of theneutral axis relevant to the step considered is to be obtained by means of an iterative process, imposing theequilibrium among the stresses acting in all the hull elements.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-1

Once the position of the neutral axis is known and the relevant stress distribution in the section structuralelements is obtained, the bending moment of the section Mi around the new position of the neutral axis, whichcorresponds to the curvature χi imposed in the step considered, is to be obtained by summing the contribution
given by each element stress.
The main steps of the incremental-iterative approach described above are summarised as follows (see also Fig
1):
Step 1Divide the transverse section of hull into stiffened plate elements.

Step 2

Define stress-strain relationships for all elements as shown in Tab 1

Step 3

Initialize curvature χ1 and neutral axis for the first incremental step with the value of incremental
curvature (curvature that induces a stress equal to 1% of yield strength in strength deck) as:
ReHEχ 1 = Δχ =zD − N
0.01

where:
zD : Z co-ordinate, in m, of strength deck at side, with respect to reference co-ordinate defined in Ch
1, Sec 4, [4]Step 4

Calculate for each element the corresponding strain εi = χ zi εi = χ (zi-zNA) and the corresponding stress

σi
Step 5Determine the neutral axis zNA_cur at each incremental step by establishing force equilibrium over thewhole transverse section as:
ΣAi σi = ΣAj σj (i-th element is under compression, j-th element under tension)

Step 6

Calculate the corresponding moment by summing the contributions of all elements as:
MU =Step 7∑σ A (z − z
Ui

i

i

NA _ cur)Compare the moment in the current incremental step with the moment in the previous incremental
step. If the slope in M-χ relationship is less than a negative fixed value, terminate the process anddefine the peak value of MU. Otherwise, increase the curvature by the amount of Δχ and go to Step 4.

2.1.3 Modeling of the hull girder cross section

Hull girder transverse sections are to be considered as being constituted by the members contributing to the hull
girder ultimate strength.
Sniped stiffeners are also to be modeled imaginarily, taking account that they doesn’t contribute to the hull
girder strength.
The structural members are categorized into an ordinary stiffener element, a stiffened plate element or a hardcorner element.
The plate panel including web plate of girder or side stringer is idealized into either a stiffened plate element, an
attached plate of an ordinary stiffener element or a hard corner element.
The plate panel is categorized into the following two kinds:- longitudinally stiffened panel of which the longer side is in the longitudinal direction, and- transversely stiffened panel of which the longer side is in the perpendicular direction to the longitudinal
direction.

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RULE CHANGE NOTICE NO.1-1•

COMMON STRUCTURAL RULES FOR BULK CARRIERSHard corner element
Hard corner elements are sturdier elements composing the hull girder transverse section, which collapse
mainly according to an elasto-plastic mode of failure (material yielding); they are generally constituted by
two plates not lying in the same plane.
The extent of a hard corner element from the point of intersection of the plates is taken equal to 20tp ontransversely stiffened panel and to 0.5s on a longitudinally stiffened panel. (See Fig 6)
where:
tp : Gross offered thickness of the plate, in mms: Spacing of the adjacent longitudinal stiffener, in m

Bilge, sheer strake-deck stringer elements, girder-deck connections and face plate-web connections on large
girders are typical hard corners.
•

Ordinary stiffener element
The ordinary stiffener constitutes an ordinary stiffener element together with the attached plate.
The attached plate width is in principle:- equal to the mean spacing of the ordinary stiffener when the panels on both sides of the stiffener are
longitudinally stiffened, or- equal to the width of the longitudinally stiffened panel when the panel on one side of the stiffener islongitudinally stiffened and the other panel is of the transversely stiffened. (See Fig 6)•

Stiffened plate element
The plate between ordinary stiffener elements, between an ordinary stiffener element and a hard corner
element or between hard corner elements is to be treated as a stiffened plate element. (See Fig 6)

s1=Min(20tp,s2/2)
s2-s1-s３/2

s2-(s1+s3)/2

s1

s2

s3

(Longitudinally (Transversely (Longitudinally
stiffened panel) stiffened panel) stiffened panel)s2(Transversely
stiffened panel)

s4/2

s3

s4

(Longitudinally
stiffened panel)

Ordinary stiffener element
Stiffened plate element
Hard corner element
Figure 6: Extension of the breadth of the attached plating and hard corner element

The typical examples of modeling of hull girder section are illustrated in Figs 7 and 8.
Notwithstanding the foregoing principle these figures are to be applied to the modeling in the vicinity of upper
deck, sheer strake and hatch side girder.

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COMMON STRUCTURAL RULES FOR BULK CARRIERS
s2

s3

s1/2

s2/2

s2/2

s3/2

s3/2

s6/2

s1/2

s7

s7/2

s4/2

s4

s6

s4/2

s6/2

s1

RULE CHANGE NOTICE NO.1-1

s7/2: Ordinary stiffener element: Hard corner element

2
s 8/

2
s 8/

s8

Figure 7: Extension of the breadth of the attached plating and hard corner element

Hard corner element
Ordinary stiffener element
Stiffened plate element

Figure 8: Examples of the configuration of stiffened plate elements, ordinary stiffener elements
and hard corner elements on a hull section

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RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERS(Note)(1) In case of the knuckle point as shown in Fig 9, the plating area adjacent to knuckles in the plating with anangle greater than 30 degrees is defined as a hard corner. The extent of one side of the corner is taken equal
to 20tp on transversely framed panels and to 0.5s on longitudinally framed panels from the knuckle point.

Knuckle pointαFigure 9: The case of plating with knuckle point(2) Where the plate members are stiffened by non-continuous longitudinal stiffeners, the non-continuous
stiffeners are considered only as dividing a plate into various elementary plate panels.
(3) Where the opening is provided in the stiffened plate element, the openings are to be considered inaccordance with Ch 5 Sec 1, [1.2.7], [1.2.8] and [1.2.9].
(4) Where attached plating is made of steels having different thicknesses and/or yield stresses, an average
thickness and/or average yield stress obtained by the following formula are to be used for the calculation.

t s +t s
t= 11 2 2,s

ReHp =

ReHp1t1s1 + ReHp 2t2 s2
ts

Where,
ReH1, ReH2, t1, t2, s1, s2 and s are shown in Fig 10.

s
s1

s2

t1
ReHp1

t2
ReHp2

Figure 10: Element with different thickness and yield strength

2.2 Load-end shortening curves σ-ε2.2.1 Stiffened plate element Plating panels and ordinary stiffeners element

Stiffened plate element Plating panels and ordinary stiffener, element composing the hull girder transverse
sections may collapse following one of the modes of failure specified in Tab 1.

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COMMON STRUCTURAL RULES FOR BULK CARRIERS•RULE CHANGE NOTICE NO.1-1

Where the plate members are stiffened by non-continuous longitudinal stiffeners, the stress of the element is
to be obtained in accordance with [2.2.3] to [2.2.7], taking into account the non-continuous longitudinal
stiffener.
In calculating the total forces for checking the hull girder ultimate strength, the area of non-continuous
longitudinal stiffener is to be assumed as zero.

•

Where the opening is provided in the stiffened plate element, the considered area of the stiffened plateelement is to be obtained by deducting the opening area from the plating in calculating the total forces forchecking the hull girder ultimate strength. The consideration of the opening is in accordance with therequirement in Ch 5 Sec 1, [1.2.7] to [1.2.9].

•

For stiffened plate element, the effective breadth of plate for the load shortening portion of the stress-strain
curve is to be taken as full plate breadth, i.e. to the intersection of other plate or longitudinal stiffener – notfrom the end of the hard corner element nor from the attached plating of ordinary stiffener element, if any.
In calculating the total forces for checking the hull girder ultimate strength, the area of the stiffened plateelement is to be taken between the hard corner element and the ordinary stiffener element or between thehard corner elements, as applicable.

Table 1:

Modes of failure of stiffened plate element plating panel and ordinary stiffeners
element
Element

Mode of failure

Curve σ−εdefined in

Lengthened
stiffenedplate
element Elasto-plastic collapse
transversely framed plating panel or ordinary
stiffeners element[2.2.3]

Shortened ordinary stiffeners element

Beam column buckling[2.2.4]

Torsional buckling[2.2.5]Web local buckling of flanged profiles[2.2.6]Web local buckling of flat bars

[2.2.7]

Shortened
stiffened
plate
transversely framed plating panel

element Plate buckling[2.2.8]2.2.2 Hard corners element

Hard corners are sturdier elements composing the hull girder transverse section, which collapse mainly
according to an elasto-plastic mode of failure (material yielding). These elements are generally constituted of
two plates not lying in the same plane. Bilge, sheer strake-deck stringer elements, girder-deck connections andface plate-web connections on large girders are typical hard corners.
The relevant load-end shortening curve σ-ε is to be obtained for lengthened and shortened hard corners
according to [2.2.3].

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RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERS

2.2.3 Elasto-plastic collapse of structural elements

The equation describing the load-end shortening curve σ-ε for the elasto-plastic collapse of structural elementscomposing the hull girder transverse section is to be obtained from the following formula, valid for both positive(shortening) and negative (lengthening) strains (see Fig 2):

σ = Φ ReHσ = Φ ReHA

where:ReHA: Equivalent minimum yield stress, in N/mm2, of the considered element, obtained by the following
formula

ReHA =
ΦεReHp Ap + ReHs As
Ap + As: Edge function, equal to:Φ = -1for ε < −1

Φ=εfor −1 ≤ ε ≤ 1

Φ=1for ε > 1

: Relative strain, equal to:

ε=

εE
εY

εE

: Element strainεY: Strain at yield stress in the element, equal to:

εY =

ReH
E

εY =

ReHA
E
ReHA

-ReHA

Figure 2: Load-end curve σ-ε for elasto plastic collapse
2.2.4 Beam column buckling

The equation describing the load-end shortening curve σCR1-ε for the beam column buckling of ordinary
stiffeners composing the hull girder transverse section is to be obtained from the following formula (see Fig 3):
σ CR1 = Φσ C1

AStif + 10bE t p
AStif + 10 st p

σ CR1 = Φσ C1AS + ApE
AS + Ap

where:

PAGE 14 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-1

Φ: Edge function defined in [2.2.3]

AStif: Net sectional area of the stiffener, in cm2, without attached plating

σC1: Critical stress, in N/mm2, equal to:σ C1 =⎛σ C1 = ReH ⎜⎜1 −⎝⎛σ C1 = ReHB ⎜⎜1 −⎝ReHB

for σ E1 ≤

ReH
ε
2

ReH ε ⎞⎟
4σ E1 ⎟⎠for σ E1 >

ReH
ε
2

ReHB ε ⎞⎟4σ E1 ⎟⎠for σ E1 >

ReHB
ε
2

σ E1
ε

σ E1 ≤ReHB
ε2: Equivalent minimum yield stress, in N/mm2, of the considered element, obtained by the following
formulaReHp ApE1l pE + ReHs AslsE

ReHB =ApE1

ApE1l pE + AslsE: Effective area, in cm2, equal to

ApE1 = 10bE1t p
lpE: Distance, in mm, measured from the neutral axis of the stiffener with attached plate of width bE1 to thebottom of the attached platelsE: Distance, in mm, measured from the neutral axis of the stiffener with attached plate of width bE1 tothe top of the stiffenerε: Relative strain defined in [2.2.3]

σE1: Euler column buckling stress, in N/mm2, equal to:σ E1 = π 2 E

IE
AE l 210 −4

IE: Net moment of inertia of ordinary stiffeners, in cm4, with attached shell plating of width bE1

bE1: Effective width, in m, of the attached shell plating, equal to:b E1 =sβE

bE1 = sβ E = 10 3

s

εReH

tp

E

for β E > 1.0
for β E ≤ 1.0

β E = 103

s
tp

εReHp
E

AE ApE : Net sectional area, in cm2, of ordinary stiffeners with attached shell plating of width bE, equal to:

ApE = 10bE t p

PAGE 15 OF 171

RULE CHANGE NOTICE NO.1-1
bE

COMMON STRUCTURAL RULES FOR BULK CARRIERS: Effective width, in m, of the attached shell plating, equal to:⎛ 2.25 1.25 ⎞bE = ⎜− 2 ⎟s⎜ ββ E ⎟⎠⎝ E

for β E > 1.25

bE = sfor β E ≤ 1.25

Figure 3: Load-end shortening curve σCR1-ε for beam column buckling
2.2.5 Torsional buckling
The equation describing the load-end shortening curve σCR2-ε for the flexural-torsional buckling of ordinary

stiffeners composing the hull girder transverse section is to be obtained according to the following formula (seeFig 4).

σ CR 2 = Φ

AStiff σ C 2 + 10st pσ CP

σ CR 2 = Φ

AStiff + 10st p

Asσ C 2 + Apσ CP
As + Ap

where:

Φ: Edge function defined in [2.2.3]

AStiff : Net sectional area of stiffener, in cm2, without attached plate

σC2: Critical stress, in N/mm2, equal to:σ C2 =σ E2
ε⎛σ C 2 = ReH ⎜⎜1 −⎝ReH ε ⎞⎟
4σ E 2 ⎟⎠⎛σ C 2 = ReHs ⎜⎜1 −⎝for σ E 2 ≤

ReH
ε
2

for σ E 2 >

ReH
ε
2

ReHs ε ⎞⎟4 σ E 2 ⎟⎠for σ E 2 >σ E2 ≤

ReHs
ε
2

ReHs
ε
2

σE2

: Euler torsional buckling stress, in N/mm2, defined in Ch 6, Sec 3, [4.3]ε: Relative strain defined in [2.2.3]

σCP: Buckling stress of the attached plating, in N/mm2, equal to:⎛ 2.25 1.25 ⎞− 2 ⎟ ReH⎜ β
β E ⎟⎠⎝ E

βE⎛ 2.25 1.25 ⎞− 2 ⎟⎟ ReHp
βE ⎠
⎝ βE

σ CP = ⎜σ CP = ⎜⎜for β E > 1.25

σ CP = ReH

σ CP = ReHp

for β E ≤ 1.25

: Coefficient defined in [2.2.4]

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COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-1

Figure 4: Load-end shortening curve σCR2-ε for flexural-torsional buckling
2.2.6 Web local buckling of ordinary stiffeners made of flanged profiles

The equation describing the load-end shortening curve σCR3-ε for the web local buckling of flanged ordinary
stiffeners composing the hull girder transverse section is to be obtained from the following formula:σ CR 3 = ΦReH

10 3 bE t p + hwe t w + b f t f

σ CR 3 = Φ

10 3 st p + hw t w + b f t f

103 bE t p ReHp + (hwet w + b f t f ) ReHs
103 st p + hwt w + b f t f

where

Φ

: Edge function defined in [2.2.3]

bE: Effective width, in m, of the attached shell plating, defined in [2.2.4]

hwe: Effective height, in mm, of the web, equal to:βw =for β w > 1.25

hwe = hw

for β w ≤ 1.25

ε ReH

hw
tw

ε

⎛ 2.25 1.25 ⎞hwe = ⎜
− 2 ⎟ hw
⎜ βw
β w ⎟⎠⎝βw =E

hw ε ReHs
tw
E: Relative strain defined in [2.2.3]

2.2.7 Web local buckling of ordinary stiffeners made of flat bars

The equation describing the load-end shortening curve σCR4-ε for the web local buckling of flat bar ordinary
stiffeners composing the hull girder transverse section is to be obtained from the following formula (see Fig 5):

σ CR 4 = Φ

10 st Pσ CP + AStiff σ C 4

σ CR 4 = Φ

AStiff + 10st P

Apσ CP + Asσ C 4
Ap + As

where:

Φ: Edge function defined in [2.2.3]

AStiff : Net sectional area of stiffener, in cm2, without attached plateσCP: Buckling stress of the attached plating, in N/mm2, defined in [2.2.5]

σC4: Critical stress, in N/mm2, equal to:σ C4 =σ E4
εfor σ E 4 ≤

ReH
ε
2

PAGE 17 OF 171

σ E4 ≤ReHs
ε2

RULE CHANGE NOTICE NO.1-1⎛

σ C 4 = ReH ⎜⎜1 −⎝⎛σ C 4 = ReHs ⎜⎜1 −⎝σE4

COMMON STRUCTURAL RULES FOR BULK CARRIERSReH ε ⎞⎟
4σ E 4 ⎟⎠for σ E 4 >

ReH
ε
2

ReHs ε ⎞⎟4σ E 4 ⎟⎠for σ E 4 >

ReHs
ε
2

: Local Euler buckling stress, in N/mm2, equal to:⎛t ⎞2

σ E 4 = 160000⎜⎜ w ⎟⎟⎝ hw ⎠ε: Relative strain defined in [2.2.3].

Figure 5: Load-end shortening curve σCR4-ε for web local buckling
2.2.8 Plate buckling
The equation describing the load-end shortening curve σCR5-ε for the buckling of transversely stiffened panels

composing the hull girder transverse section is to be obtained from the following formula:⎧ ReH Φ⎪⎪2⎡ s ⎛ 2.25 1.25 ⎞σ CR 5 = min ⎨1 ⎞ ⎤⎛ s ⎞⎛⎪ΦReH ⎢ l ⎜⎜ β − β 2 ⎟⎟ + 0.1⎜1 − l ⎟⎜⎜1 + β 2 ⎟⎟ ⎥⎠⎝⎝⎢⎣ ⎝ E
E ⎠
E ⎠ ⎥
⎪⎩
⎦
⎧ ReHp Φ⎪⎪2⎡ s ⎛ 2.25 1.25 ⎞σ CR 5 = min ⎨1 ⎞ ⎤⎛ s ⎞⎛⎪ΦReHp ⎢ l ⎜⎜ β − β 2 ⎟⎟ + 0.1⎜1 − l ⎟⎜⎜1 + β 2 ⎟⎟ ⎥⎝⎠⎝⎢⎣ ⎝ E
E ⎠
E ⎠ ⎥
⎪⎩
⎦
where:

Φ: Edge function defined in [2.2.3].

β E = 103

s
tp

εReH
E

β E = 103

s
tp

εReHp
E

s

: plate breadth, in m, taken as the spacing between the ordinary stiffenersl: longer side of the plate, in m.

PAGE 18 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-1(Hull Girder Strength)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and inthat case any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 19 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for the Changes Regarding Hull Girder
Strength
1. Reason for the Rule Change in:
1.1 Chapter 5, Section 1, [2.2.2], [2.2.3] and [5.1.3]
These changes are made to clarify the requirements (Refer to KC ID 353, 453 and 459).
The way to consider any shear force corrections forward and aft of transverse bulkheads is
specified in [2.2.2] and [5.1.3].
It is specified that the total mass M in those holds loaded in non-homogeneous loading
conditions deadweight such as water ballast and fuel oil tank in double bottom, bounded byside girders in way of hopper tank plating or longitudinal bulkhead.
In addition, the symbol “TLC” defined in Chapter 1 Section 4, [2.1.1] is defined differently in
Chapter 5 Section 1.
1.2 Chapter 5, Appendix 1, Symbols, [2.1.1], [2.1.3], [2.2.1] to [2.2.8]
These changes are made to clarify the requirements (Refer to KC ID 499, 519 and 520).
The position and extent of the hard corners is specified in order to provide the equivalentdefinition of hard corners used in the CSR for Bulk Carriers regarding hull girder ultimate
strength calculations to the one used in the CSR for Oil Tankers.
The calculation method is specified for those cases where any attached plating and stiffeners
are made of steels having different yield stresses and/or thicknesses.
The way to consider non-continuous stiffeners for the hull girder ultimate strength calculationis specified.
In cases where attached plating and stiffeners are made of steel having different yield stresses,
load end shortening curves are to be separately calculated for the stiffeners and the attachedplates, i.e. the method is similar to the “weighted average method on area” in consideration of
the net area of stiffeners and attached plates because this approach is very simple and easy tounderstand.
However, as described in Annex 1, this approach sometimes give a smaller ultimate strength
in comparison to the results attained from a 3D non-linear FEA in cases where the yield stressof stiffeners is smaller than that of any attached plates. This is because the area of suchattached plates is greater than that of the stiffeners. Normally, such a case is scarcely found in
actual designs.
From the results of 3D non-linear FEA, it has been found that any underestimation of the load
end shortening curves for beam column buckling of such stiffened panels can be resolved byconsidering the first moment of such stiffened panels. In addition, load end shortening curves
for modes of failure other than beam column buckling can be evaluated by using the yieldstress of stiffeners and attached plates, respectively.

2. Summary of Rule Changes
2.1 Chapter 5, Section 1, [2.2.2], [2.2.3] and [5.1.3]
The shear force correction is to be considered independently forward and aft of transverse
bulkheads for any hold considered.
In addition, the total mass M may include masses of water ballast in double bottoms tanks,
bounded by side girders in way of hopper tank plating or longitudinal bulkheads, if such
spaces are loaded for the non-homogeneous loading condition considered.
Finally, the symbol “TLC” is changed to “TLC_mh”
PAGE 20 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

2.2 Chapter 5, Appendix 1, [2.1.1], [2.1.3], [2.2.1] to [2.2.8]
2.2.1 Chapter 5, Appendix 1, Symbols and [2.1.1](1) Definitions of necessary symbols are added in order to evaluate stiffened panels in cases
where any attached plating and stiffeners are made of steel having different stresses.
(2) Editorial correction in [2.1.1] is made.
2.2.2 Ch 5 Appendix 5 [2.1.3]
The new paragraph [2.1.3] is added for the modelling of hull girder cross sections.
The extent of hard corner elements from corners is taken equal to 20tp on transversely framed
panels and to 0.5s on longitudinally framed panels.
In cases where attached plating is made of steels having different thicknesses and/or yieldstresses, average thickness and/or average yield stress are to be used in calculations.
2.2.3 Ch 5 Appendix 5, [2.2.1] to [2.2.8]
The provisions regarding the definition of hard corners specified in [2.2.2] are shifted to a
new paragraph [2.1.3].
In addition, the ways to calculate the load-end shortening curves of the following cases are
explained: in cases where attached plating and stiffener are made of steels having different
yield stresses; in cases where plate members are stiffened by non-continuous longitudinal
stiffeners; in cases where openings are provided in stiffened plate elements; and, in cases
where stiffened plate elements are provided.

3. Impact on Scantling
3.1 Chapter 5, Section 1, [2.2.2], [2.2.3] and [5.1.3]
There is no change in terms of steel weight by comparing that before and after the proposed
rule change.
3.2 Chapter 5, Appendix 1, [2.1.1], [2.1.3], [2.2.1] to [2.2.8]
There is no change in terms of steel weight by comparing that before and after the proposed
rule change.

PAGE 21 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Annex 1: Evaluation method of the load end shortening curve forstiffened panel where the attached plate and stiffener are made ofsteel having different yield stresses
1. Introduction
The evaluation methodology of hull girder ultimate strength in CSR-BC is based on Smith’s method.
In cases where any attached plates and stiffeners are made of steel having different yield stresses,
the procedures and formulae for load end shortening curves are not described in the current Rules.
The following two methods to deal with such elements were considered.
(1) Using lower yield stresses.
(2) Considering plate elements and stiffener elements to be separate elements, and calculating theload-end shortening curves for the stiffener and the attached plating separately as follows:
For stiffeners: by adding attached plating having the same yield stress as the stiffener and thendetermining the shortening curve and the stress to be applied to the stiffener
only.
For attached plating: by adding a stiffener having the same yield stress as the attached plating
and then determining the shortening curve and the stress to be applied to theattached plating only.
Finally, load end shortening curves for stiffened panels can be obtained by adding the load end
shortening curve for the stiffener to the load end shortening curve for the attached plating anddividing the sum by the total area of the stiffened panel.
This method is called “Method A”. It has been confirmed that any load end shortening curve
obtained by this method is nearly equal to that obtained by using the average yield stress considering
areas of any stiffeners and attached plates.
It is obvious that the method specified in (1) above gives a conservative load end shortening curve
because the higher yield strengths of stiffeners or panels is not taking into account. On the other hand,because Method A is simple and easy to understand, this method has been indicated in the IACS KC
DB 520 as a practicable approach to evaluate the load end shortening curves of stiffened panels withdifferent yield stresses between attached plates and stiffeners
However, there are some cases where Method A may give inadequate values of the load end
shortening curves of stiffened panels of different materials used for the attached plate and the stiffener.
Specifically, in cases where stiffened panel elements consist of attached plates of HT36 andstiffeners of HT 32, the load end shortening curves of such elements are sometimes overestimated incomparison to the results of 3D non-linear FEAs (FEA). On the contrary, in cases where elements
consist of attached plates of HT32 and stiffeners of HT36, the load end shortening curves of such
stiffened panel elements are sometimes underestimated in comparison to the results of FEA.
Although stiffeners with yield stresses lower than that of attached plates are rarely used in actual
ship design, any underestimated result obtained by Method A should be resolved.
Since the areas of attached plates are larger than that of stiffeners in most cases, the load end
shortening curve of the stiffened panel obtained by method A is affected by the yield strength of theattached plating. However, in reality, the yield stress of the stiffener has great impact on its load end
shortening curve if beam-column buckling takes place, the parameters other than the areas of stiffeners
and attached plates should be considered to accurately estimate the load end shortening curves of
stiffened panels of attached plates and stiffeners having different yield stresses
In order to reduce the dependency on the areas of attached panels, the first moment of stiffened
panels instead of the areas of attached plates and stiffeners are considered.
This method is called “Method B”.
For example, using Method B, load end shortening curves of beam column buckling are calculated
in the following manner:

PAGE 22 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

ReHs : yield stress of the stiffener
As : area of the stiffener

StiffenerlsE : distance to the top of the stiffener from the neutral
axis of the stiffened panel having the attached platewith bE1

lsE

As
Neutral Axis

lpE

Attached plate

ReHp : yield stress of the attached platebE1 : effective width of the attached plate.
bE1

ApE : area of the attached plate with effective
breadth bE1.
lpE : distance to the bottom of the attached plate fromthe neutral axis of the stiffened panel having theattached plate with bE1

ApE

Equivalent yield stress ReHB of the stiffened panel can be expressed by the following formula:

ReHB =

ReHp ApE1l pE + ReHs AslsE
ApE1l pE + AslsE

The load end shortening curve for the beam column buckling is obtained from the following
formula:σ CR1 = Φσ C1AS + ApE
AS + Ap

where:

Φ andε : defined in [2.2.3], Ch 5 Appendix 1 of the Rules.
σC1: Critical stress, in N/mm2, equal to:σ C1 =σ E1
ε⎛σ C1 = ReHB ⎜⎜1 −⎝ReHB ε ⎞⎟4σ E1 ⎟⎠

forσ E1 ≤

ReHB
ε
2

for

σ E1 >ReHB
ε2

ApE1 : Effective area, in cm2, equal to 10bE1t p

σE1: Euler column buckling stress, in N/mm2, equal to:σ E1 = π 2 E

IE
AE l

2

10 −4

IE

: Net moment of inertia of ordinary stiffeners, in cm4, with attached shell plating of width bE1

bE1: Effective width, in m, of the attached shell plating, equal to:b E1 =sfor β E > 1.0

βE

for β E ≤ 1.0

bE1 = sβ E = 103

s
tp

εReHp
E
PAGE 23 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

ApE

COMMON STRUCTURAL RULES FOR BULK CARRIERS: Net sectional area, in cm2, of attached shell plating of width bE, equal to:

ApE = 10bE t p
bE: Effective width, in m, of the attached shell plating, equal to:⎛ 2.25 1.25 ⎞− 2 ⎟sbE = ⎜⎜ βE
β E ⎟⎠⎝

for β E > 1.25

bE = sfor β E ≤ 1.25

3D non-linear FEAs are carried out for the purpose of verifying the accuracy of the ultimate strengthof stiffened panels obtained by Method B as well as Method A.

2. FEA
96 cases of the collapse analyses of the stiffened panels with non-linear FEM have been performed.
The scantlings of stiffened plates analysed are listed in Table 1. As seen in Fig.1, the stiffened panels
are modelled in the range of double span – double bay. Periodical continuous conditions are imposed
along the edges of the model in the longitudinal and transverse directions. The material properties usedin the analyses are as follows:
Young’s Modulus : E = 206000 N/mm2
Poisson’s Ratio: n = 0.3
Strain Hardening Rate: Η’=0
Case 1 : 315 N/mm2 for attached plate and 315 N/mm2 for stiffener
Case 2 : 315 N/mm2 for attached plate and HT 355 N/mm2for stiffener (Different material case)
Case 3 : 355 N/mm2 for attached plate and HT 315 N/mm2 for stiffener (Different material case)
Case 4 : 355 N/mm2 for attached plate and 355 N/mm2 for stiffener
Table 1 Scantling and yield strength of each analysis case
Stiffener
Type

Angle

T-bar

Flat-bar

Attached plate

Size (mm)Lengtha (mm)

Breadthb (mm)

Aspect ratio
(a/b)

2400

800

3.0

4000

800

5.0

3600

900

4.0

5400

900

6.0

2400

800

3.0

4000

800

5.0

250x90x12/16

400x120x13/18

300x15

PAGE 24 OF 171

Thickness
tp (mm)
10
15
20
25
10
15
20
25
10
15
20
25
10
15
20
25
10
15
20
25
10
15

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

20
25

Fig.1 Model of stiffened panel

3. Verification results of the two methods
The results of the FEA, method A and Method B analyses are shown in Fig. 2 to Fig. 7. In thesefigures, FEA results are indicated by a line, the results of Method A and Method B are indicated bysymbols.
Generally, it was found that there is good agreement between the results obtained by both methods
and those by FEA from these figures except those cases where the plate thickness is 10mm.
However, considering the actual thickness of hull transverse members, both methods can be used
for the evaluation of ultimate strength.

Fig. 2 Comparison on ultimate strength (Angle a/b=3.0)

PAGE 25 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Fig. 3 Comparison on ultimate strength (Angle a/b=5.0)

Fig. 4 Comparison on ultimate strength (T-bar a/b=4.0)

Fig. 5 Comparison on ultimate strength (T-bar a/b=6.0)

PAGE 26 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

Fig. 6 Comparison on ultimate strength (Flat-bar a/b=3.0)

Fig. 7 Comparison on ultimate strength (Flat-bar a/b=5.0)
In order to discuss the accuracy of the results of Method A and Method B, a ratio obtained by
dividing the results of both methods into that of FEA is given in Fig. 8 to Fig. 13.
Here, we call attention to the results of Case 2 and Case 3 in cases where any attached plates andstiffeners are made of steels having different yield stresses.
The ultimate strengths of all of the calculation conditions in Case 3 evaluated by Method A always
are greater than those in Case 3.
In addition, the error (difference) becomes greater in those cases where the thickness of the attachedplate with large aspect ratio becomes greater. This is because the ultimate strength of the stiffened
panels is strongly affected by the yield strengths of attached plates.
On the other hand, the error of any results obtained by Method B seems to be smaller than thoseobtained by Method A, and any tendencies obtained by Method A cannot be observed in the results
obtained by Method C.

PAGE 27 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Fig. 8 Comparison on accuracy of estimation method (Angle a/b=3.0)

Fig. 9 Comparison on accuracy of estimation method (Angle a/b=5.0)

Fig. 10 Comparison on accuracy of estimation method (T-bar a/b=4.0)

PAGE 28 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

Fig. 11 Comparison on accuracy of estimation method (T-bar a/b=6.0)

Fig. 12 Comparison on accuracy of estimation method (Flat-bar a/b=3.0)

Fig. 13 Comparison on accuracy of estimation method (Flat-bar a/b=5.0)
For the purpose of confirming the accuracy of any results obtained by Method A and Method B,
average values and coefficients of variation (COV) are calculated and those results are given in Figure
14 and 15.

PAGE 29 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

Fig. 14 Averages of Ultimate Strength in Each Case

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Fig. 15 Coefficients of Variation in Each Case

From Figure 15, it is obvious that the variance of any results obtained by method B is small.
This means the accuracy of any results obtained by Method B is higher than those results obtained by
Method A.

4. Conclusion
Two methods to estimate the ultimate strength of stiffened panels in cases where attached plates andstiffeners are made of steel having different yield stresses are considered.
One is Method A, where the yield stress used in the estimation of beam-column buckling is
calculated so as to be the weighted average value of the yield stresses of the stiffener and the attachedplating according to their area.
The other is method B, where the yield stress in the estimation of beam-column buckling is set to theweighted average value of the yield stresses of the stiffener and the attached plating according to the
product of their areas and their distances from the neutral axis.
In order to evaluate the accuracy of the ultimate strength of the stiffened panel obtained by bothmethods, the results obtained by both methods are compared to those obtained by 3D non-linear FEAs.
From these comparison works, the following findings are obtained.
(1) The method A is very simple and practicable, but it may overestimated the ultimate strength in
the case that the yield strength of the stiffener is lower than that of the attach plating(2) Method B is not as simple and practicable as Method A, but it gives more accurate ultimate
strength values for stiffened panels in comparison to those obtained by Method A.
Therefore, in cases where attached panels and stiffeners are made of steel having different yieldstresses, Method B should be used for the evaluation of the load end shortening curve thereof.
The text in the RCP is based on this.

PAGE 30 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-2

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-2(Hatch Covers)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 31 OF 171

RULE CHANGE NOTICE NO.1-2

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-2.

CHAPTER 9 OTHER STRUCTURES
Section 5 HATCH COVERS

Symbols

For symbols not defined in this Section, refer to Ch 1, Sec 4.
pS: Still water pressure, in kN/m2, defined in [4.1]pW: Wave pressure, in kN/m2, defined in [4.1]pC: Pressure acting on the hatch coaming, in kN/m2, defined in [6.2]

FS, FW : Coefficients taken equal to:
FS = 0 and FW = 0.9

for ballast water loads on hatch covers of the cargo ballast holdFS = 1.0 and FW = 1.0

in other casess: Length, in m, of the shorter side of the elementary plate panell: Length, in m, of the longer side of the elementary plate panelbp: Effective width, in m, of the plating attached to the ordinary stiffener or primary supporting member,defined in [3]w: Net section modulus, in cm3, of the ordinary stiffener or primary supporting member, with an attachedplating of width bp

Ash: Net shear sectional area, in cm2, of the ordinary stiffener or primary supporting memberm: Boundary coefficient for ordinary stiffeners and primary supporting members, taken equal to:m = 8 , in the case of ordinary stiffeners and primary supporting members simply supported at bothends or supported at one end and clamped at the other end
m = 12 , in the case of ordinary stiffeners and primary supporting members clamped at both endstC

: Total corrosion addition, in mm, defined in [1.4]σa , τa : Allowable stresses, in N/mm2, defined in [1.5]1. General
1.5 Allowable stresses
1.5.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 15(6) and 16(5))

The allowable stresses σa and τa, in N/mm2, are to be obtained from Tab 2.

PAGE 32 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-2

Table 2 Allowable stresses, in N/mm2
Members ofSubjected toσa, in N/mm2

τa, in N/mm2

Weathertight hatch cover
Pontoon hatch cover
Weathertight hatch cover and pontoon
hatch cover

External pressure, as defined in Ch
4, Sec 5, [2][5.2.1]

0.80 ReH
0.68 ReH
0.90 ReH

0.46 ReH
0.39 ReH
0.51 ReH

Other loads, as defined in Ch 4 ,Sec5, [5.1.1] and Ch 4, Sec 6, [2]5. Strength check
5.2 Plating
5.2.3 Critical buckling stress check
The compressive stress σ in the hatch cover plating, induced by the bending of primary supporting members,parallel to the direction of ordinary stiffeners is to comply with the following formula:

σ≤

0.88
σ C1
S

where:
S: Safety factor defined in Ch 6, Sec 3

σC1: Critical buckling stress, in N/mm2, taken equal to:σ C1 = σ E1⎛

σ C1 = ReH ⎜⎜1 −
⎝

⎛ t ⎞
⎟
⎝ 1000 s ⎠forσ E1 ≤

ReH
2

ReH ⎞
⎟ for
4σ E1 ⎟⎠σ E1 >ReH
2

2

σ E1 = 3.6 E ⎜t: Net thickness, in mm, of plate panel

The compressive stress σ in the hatch cover plating, induced by the bending of primary supporting members,
perpendicular to the direction of ordinary stiffeners is to comply with the following formula:

σ≤

0.88
σ C2
S

where:
S: Safety factor defined in Ch 6, Sec 3

σC2: Critical buckling stress, in N/mm2, taken equal to:σ C2 = σ E2⎛

σ C 2 = ReH ⎜⎜1 −
⎝

⎛

⎞
t
⎟
⎟
⎝ 1000 s s ⎠forσ E2 ≤

ReH
2

ReH ⎞
⎟ for
4σ E 2 ⎟⎠σ E2 >ReH2

2

σ E 2 = 0.9 m E ⎜⎜PAGE 33 OF 171

RULE CHANGE NOTICE NO.1-2
m

COMMON STRUCTURAL RULES FOR BULK CARRIERS: Coefficient taken equal to:2⎡ ⎛ s ⎞2 ⎤2.1
m = c ⎢1 + ⎜⎜ s ⎟⎟ ⎥⎢ ⎝ l s ⎠ ⎥ ψ + 1.1⎣⎦t: Net thickness, in mm, of plate panelss: Length, in m, of the shorter side of the plate panells: Length, in m, of the longer side of the plate panelψ: Ratio between smallest and largest compressive stressc: Coefficient taken equal to:c = 1.3 when plating is stiffened by primary supporting members
c = 1.21 when plating is stiffened by ordinary stiffeners of angle or T typec = 1.1 when plating is stiffened by ordinary stiffeners of bulb typec = 1.05 when plating is stiffened by flat bar
c = 1.30 when plating is stiffened by ordinary stiffeners of U type. The higher c value but not greaterthan 2.0 may be taken if it is verified by buckling strength check of panel using non-linear FEA anddeemed appropriate by the Society.
An averaged value of c is to be used for plate panels having different edge stiffeners.

In addition, Tthe bi-axial compression stress in the hatch cover plating, when calculated by means of finite
element analysis, is to comply with the requirements in Ch 6, Sec 3.

5.3 Ordinary stiffeners
5.3.2 Minimum net thickness of web
The web net thickness of the ordinary stiffener, in mm, is to be not less than the minimum values given in [5.2.2]4mm.

5.4 Primary supporting members
5.4.2 Minimum net thickness of web
The web net thickness of primary supporting members, in mm, is to be not less than the minimum values given

in [5.2.2] 6mm.

PAGE 34 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-2

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-2(Hatch Covers)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are, individuallyand collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individually and collectively,
assume no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on theinformation or advice in this document or howsoever provided, unless that person has signed a contract with therelevant IACS Member entity for the provision of this information or advice and in that case any responsibility or
liability is exclusively on the terms and conditions set out in that contract.

PAGE 35 of 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-2

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for the Change Regarding Hatch Covers
1. Reason for the Rule Changes
1.1 Symbols
To consider the internal pressure due to ballast water in ballast hold, the load combination
coefficients are introduced in Symbols. The rule change is made to clarify the application of thesymbols Fs and Fw.
1.2 Table 2 Allowable stresses
According to ILLC and IACS UR S21, the external pressure is only external wave pressure
acting on the hatch cover. However, as the pressure is referred to Ch 4 Sec 5 [2] which are
mentioned not only the wave pressure on exposed deck but also other distributed load andconcentrated loads.
This rule change is made according to the answer in KC ID 537 in order to be in line with ILLC andIACS UR S21.
1.3 “5.2.3 Critical buckling stress”
1.3.1 Application of buckling check
When the bi-axial compression stress in the hatch cover plating calculated by means of finite
element analysis, buckling check is to be carried out in accordance with the requirement in Ch 6 Sec
3. This check is alternative check to the buckling check using the compression stress obtained by agrillage analysis as specified in IACS UR S21.
This rule change is made according to the answer in KC ID 477 in order to be in line with IACS UR
S21.
1.3.2 “c” or “F1” factor for ordinary stiffener of U type
There are many hatch covers stiffened by ordinary stiffener of U type. As the ordinary stiffenerof U-type has the merit of being more resistant to rotational effect than other ordinary stiffener offlat bar, angle type or T type. However, the coefficient “c” is taken equal to 1.05 to 1.2
corresponding to the type of stiffener. Regarding this issue, the interpretation is made according to
the results as shown in Annex 1.
1.4 5.3.2 Minimum thickness of ordinary stiffener and 5.4.2 Minimum thickness of Primary
supporting member
The definition of the web minimum thickness of ordinary stiffeners and primary supporting
members was linked to the minimum requirements for the hatch cover plating, as defined in URS
21 and ILLC Reg. 16 (5.b). These rules contain no requirement for minimum web thickness forordinary stiffeners and primary supporting members. But the rules for hatch covers of CSR-BC
should have such a minimum requirement, comparable to the approach for the ship structure.
The reason is the change to the net thickness concept, which has not taken into account for the
stiffeners. Hatch cover manufactures demand that the minimum net thickness of ordinary stiffeners
plus the corrosion margin of 2mm has not to be greater than the well proven gross thickness of 6mm.
In addition, the relation to the distance between ordinary stiffeners (tmin = 10s) is only valid forthe hatch cover plating.
The rule change is made in accordance with the answer in KC ID 535.

2. Summary of the Rule Change
2.1 Symbols
The use of the coefficients Fs=0 and Fw=0.9 are limited for hatch covers of the ballast hold incase scantling check is done against the ballast water pressure.
PAGE 36 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-2

2.2 Table 2
The reference is changed to Ch 4 Sec 5 [5.2.1] from Ch 4 Sec 5 [2] and clarification of “otherload” is made.
2.3 “5.2.3 Critical buckling stress”
2.3.1 Application of buckling check
The used stress for buckling check is clarified as follows.
For uni-axial compression stress, the stress is obtained by a grillage analysis.
For bi-axial compression stress, the stresses are obtained by a FEA
2.3.2 “c” or “F1” factor for ordinary stiffener of U type
According to the results specified in Annex 1, the coefficient “c” for ordinary stiffener of Utype can be taken to higher value than 1.3. However, “c” value depends on the aspect ratio as shownin Annex 1. Therefore, the coefficient “c” is taken equal to 1.3 as a minimum, but the higher value
may be used if it is verified by buckling strength check of panel using non-linear FEA and deemed
appropriate by the Society.

In addition, the treatment of the different edge stiffeners is added according to Table 1 in Ch 6
Sec 3.
2.4 “5.3.2 Minimum thickness of web of ordinary stiffener” and “5.4.2 Minimum thickness ofPrimary supporting member”(1) The relation to the distance between ordinary stiffeners (tmin = 10s) is only valid for the hatch
cover plating. Therefore this requirement is deleted the reference to the minimum thickness ofhatch cover plate for ordinary stiffeners and primary supporting.
(2) In addition to the change, described in (1) above, the minimum net web thickness of ordinary
stiffener of 6mm has been changed to 4mm.
(3) In addition to the change, described in (2) above, the minimum net thickness of 6mm is
specified in the requirement for web of primary supporting member, but the value is the same as
the current Rule.

3. Effects and impact on scantling due to this definition
3.1 Items in 2.1, 2.2 and 2.3.1 mentioned above
As the rule change is only made for the clarification, there is no scantling impact due to thesechanges.
3.2 Items in 2.3.2 mentioned above
Regarding the U-type stiffeners, the coefficient “c” is to be an appropriate value deemed by theSociety because the factor of such stiffeners are not defined in CSR and IACS UR S21. The
minimum value is newly defined by this rule change although the used value still depends on thediscretion of the Society. Therefore, the scantling impact due to this change can not be estimated.
3.3 Item in 2.4
The minimum web thickness for ordinary stiffeners and primary supporting members isdecreased.
The impact on scantling can not be estimated in general. Depending on the hatch cover type, thehatch cover size and loads, different design criteria determine the dimensions of the structure. One
manufacturer estimates the weight increase when using the current CSR approach with 40% for
ordinary stiffeners (KC-ID. 535).

PAGE 37 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-2

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Annex 1: Technical Background for the Changes regarding F1
factor for transverse compressed plate fields in buckling check ofhatch cover plating
1. Reason for the Rule Change in Ch 9 Sec 5 [5.2.3]
It was requested to make an interpretation for the factor “c” in case of U-type stiffener inbuckling assessment of hatch covers. The factor “c” considers the torsion stiffness of thelongitudinal stiffener of an elementary plate panel under transverse compression loads. The
following values are given in the URS 11:
c = 1.3 when plating is stiffened by primary supporting members
c = 1.21 when plating is stiffened by ordinary stiffeners of angle or T typec = 1.1 when plating is stiffened by ordinary stiffeners of bulb typec = 1.05 when plating is stiffened by flat bar

The intention of this RC is to make a proposal for the “c” factor for U-type stiffener

2. Summary of the Rule Change
The derivation of the “c”-factor for U-type stiffeners based on nonlinear FE-analyses
should be treated as a future development, because this work is beyond the capability of CSR
PT1. CSR PT1 proposes to make a comparison study to estimate a F1 value by comparing thebuckling load case (BLC) 9 (clamped edges) with the reference BLC 2 (simply supported).
Both buckling load cases BLC 2 and BLC 9 are theoretical cases and the real boundary
condition of the U-Profile is in between these extreme cases. As a short term solution we
propose to use the mean buckling reduction factor κy value of both BLC's to estimate the “c”factor for U-type stiffeners.
The following diagrams show the buckling reduction factors of BLC 1 and 9 together withthe mean value and the “c”-factors as a function of c = κy(9) / κy(1) and c = κy(mean) / κy(1)for different plate thicknesses and aspect ratios.

PAGE 38 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-2

Influence of longitudinal stiffeners
with high torsional stiffness of the buckling behaviour oftransverse loaded plate panels (t=25mm)

kappa, F1

2,0
1,8

kappa BLC2

1,6

kappa BLC 91,4c=f(BLC2,9)
kappa mean

1,2c_mean

1,0
0,8
0,6
0,4
0,2
0,0
1

2

3

4

5

6

7

8

9

10

alpha

Influence of longitudinal stiffeners
with high torsional stiffness of the buckling behaviour oftransverse loaded plate panels (t=15mm)
3,0
kappa BLC2
kappa BLC 9c=f(BLC2,9)
kappa meanc_mean2,5kappa, F1

2,0
1,5
1,0
0,5
0,0
1

2

3

4

5

6

7

alpha

PAGE 39 OF 171

8

9

10

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-2

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Influence of longitudinal stiffeners
with high torsional stiffness of the buckling behaviour oftransverse loaded plate panels (t=7mm)
4,0kappa BLC2

3,5

kappa, F1

kappa BLC 93,0c=f(BLC2,9)2,5

kappa meanc_mean

2,0
1,5
1,0
0,5
0,0
1

2

3

4

5

6

7

8

9

10

alpha

The diagrams show the following dependencies•
With decreasing thickness the “c” factor increases•
With decreasing thickness the range of a constant “c” factor increases
Different hatch cover designs show aspect ratios between 3 and 8 with a majority of ratios
between 3 and 6. The plate thickness is typically below 10mm. For these parameter ranges a“c” factor of 2.0 may be assumed.
To be in line with the simple definitions of “c” in URS 11 a constant “c” value of 1.3 canbe used regardless of the thickness and aspect ratio. The diagrams leads to the assumption,that a higher value might be possible, taking the aspect ratio and plate thickness into account.
But this has to be verified as a future development for CSR-BC.

3. Effects and impact on scantling due to this definition
The highest value for “c”, given in the URS 11 is 1.3 for primary supporting members.
Higher values are not allowed by IACS up to now. Defining a constant value of 1.3 for Utype stiffeners regardless of plate field aspect ratios or thicknesses, we do not change theresult of the plate buckling check for hatch covers and this definition has no impact on
scantling.
With the selection of a higher “c” value for such kind of stiffeners, the buckling strengthof hatch cover plating, stiffened with U-type stiffeners increases with respect to transverse
loaded plate fields.

PAGE 40 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-3

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-3(Steel Coil)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 41 OF 171

RULE CHANGE NOTICE NO.1-3

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-3.

CHAPTER 4 DESIGN LOADS
Section 2 SHIP MOTION AND ACCELERATIONS
2. Ship absolute motions and accelerations
2.1 Roll
2.1.1

The roll period TR, in s, and the single roll amplitude θ, in deg, are given by:
2.3kr
TR =
GM

θ=

9000(1.25 − 0.025T R ) f p k b(B + 75)πwhere:kb: Coefficient taken equal to:
kb = 1.2 for ships without bilge keel
kb = 1.0 for ships with bilge keel

kr

: Roll radius of gyration, in m, in the considered loading condition. When kr is not known, the values
indicated in Tab 1 may be assumed.

GM: Metacentric height, in m, in the considered loading condition. When GM is not known, the values
indicated in Tab 1 may be assumed.
Table 1: Values of kr and GM
Loading condition(Alternate or homogeneous loading)
Full load condition
Steel coil loading
Normal ballast condition
Heavy ballast condition

PAGE 42 OF 171

kr
0.35B
0.42B
0.45B
0.40B

GM
0.12B
0.24B
0.33B
0.25B

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-3

CHAPTER 6 HULL SCANTLING

Section 1 PLATING
2. General requirements
2.7 Inner bottom loaded by steel coils on a wooden support
2.7.1 General
The net thickness of inner bottom, bilge hopper sloping plate and inner hull for ships intended to carry steel

coils is to comply with [2.7.2] to [2.7.4].
The provision is determined by assuming Fig 2 as the standard means of securing steel coils. In case where steel
coils are lined up two or more tier, formulae in [2.7.2] and [2.7.3] can be applied to the case that only lowest tierof steel coils is in contact with hopper sloping plate or inner hull plate. In other cases, scantlings of plate
thickness are calculated by direct strength analysis or other procedures.

Figure 2: Inner bottom loaded by steel coils
2.7.1 bis1 Accelerations
In order to calculate the accelerations, the following coordinates are to be used for the centre of gravity.

xG − sc = 0.75 l forward of aft bulkhead, where the hold of which the mid position is located forward fromH
0,45L from A.E.

PAGE 43 OF 171

RULE CHANGE NOTICE NO.1-3

COMMON STRUCTURAL RULES FOR BULK CARRIERS

xG − sc = 0.75 l afterward of fore bulkhead, where the hold of which the mid position is located afterward fromH

0,45L from A.E.

yG − sc = ε

Bh
4

⎧
3⎫ d
zG − sc = hDB + ⎨1 + (n1 − 1) ⎬ sc
2 ⎭ 2⎩
where:

ε: 1.0 when a port side structural member is considered , or -1.0 when a starboard side structural member
is considered.

Bh: breadth in m, at the mid of the hold, of the cargo hold at the level of connection of bilge hopper platewith side shell or inner hulldsc

: diameter of steel coils, in m

hDB

: height of inner bottom, in mlH

: Cargo hold length, in m

Vertical acceleration aZ, in m/s2,.are to be calculated by the formulae defined in Ch 4, Sec 2, [3.2] and tangential
acceleration aR due to roll, in m/s2 .is to be calculated by the following formula.

aR = θ

π ⎛ 2π ⎞⎜⎟180 ⎜⎝ TR ⎟⎠22

y G _ SC + R 2

where:
θ, TR and R: as defined in Ch 4 Sec 2, [3.2].
2.7.2 Inner bottom plating
The net thickness of plating of longitudinally framed inner bottom is to be not less than the value obtained, in

mm, from the following formula:t = K1

t = K1(g + aZ )F
λP RY{g (cos(C ZP Φ )cos(C ZRθ )) + a z }F
λ P RY

where:
K1: Coefficient taken equal to:K1 =1.7 slK 2 − 0.73s 2 K 22 − (l − l' )22l' (2 s + 2lK 2 )aZ: Vertical acceleration, in m/s2, defined in Ch 4, Sec 2, [3.2] [2.7.1 bis1]

Φ: Single pitch amplitude, in deg, defined in Ch 4, Sec 2, [2.2]θ: Single roll amplitude, in deg, defined in Ch 4, Sec 2, [2.1]

CZP,CZR : Load combination factor defined in Ch 4, Sec 4, [2.2]

PAGE 44 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSF

RULE CHANGE NOTICE NO.1-3: Force, in kg, taken equal to:
F = KS

Wn1n 2n3

for n 2 ≤ 10 and n3 ≤ 5lfor n 2 > 10 or n3 > 5

F = K S n1W

lS

λP: Coefficient defined in Tab 6

KS: Coefficient taken equal to:
KS = 1.4

when steel coils are lined up in one tier with a key coil

KS = 1.0

in other cases

W: Mass of one steel coil, in kg

n1: Number of tiers of steel coilsn2: Number of load points per elementary plate panel of inner bottom (See Figs 3 and 4), taken equal to.
When n3 ≤ 5 , n 2 can be obtained from Tab 3 according to the values of n3 and l / l S• in case of steel coils loaded as shown in Fig 3, n2 is obtained from Tab 3 according to the values ofn3 and l/lS
• in case of steel coils loaded as shown in Fig 4, n2 = n3

n3

: Number of dunnages supporting one steel coillS

: Length of a steel coil, in m

K2

: Coefficient taken equal to:
2

2

2

s
⎛s⎞
⎛ l ⎞ ⎛ l' ⎞K 2 = − + ⎜ ⎟ + 1.37⎜ ⎟ ⎜1 − ⎟ + 2.33
l
l
l⎠
⎝ ⎠
⎝s⎠ ⎝

l’

: Distance, in m, between outermost load points per elementary plate panel of inner bottom plate in ship
length, taken equal to: (See Figs 3 and 4). When n 2 ≤ 10 and n3 ≤ 5 , l’ can be obtained from Tab 4
according to the values of l, lS, n2 and n3. When n 2 > 10 or n3 > 5 , l’ is to be taken equal to l.
• in case of steel coils loaded as shown in Fig 3, l’ is obtained from Tab 4 according to the values ofl, lS, n2 and n3• in case of steel coils loaded as shown in Fig 4, l’ is the actual value.
2.7.3 Bilge hHopper sloping plate and inner hull plateing
The net thickness of plating of longitudinally framed bilge hopper sloping plate and inner hull is to be not lessthan the value obtained, in mm, from the following formula:t = K1

t = K1[g cos(θ 1 − θ 2 ) + aY sin θ 1 ]F ′λ P RYa hopper F 'λ p RyPAGE 45 OF 171

RULE CHANGE NOTICE NO.1-3

COMMON STRUCTURAL RULES FOR BULK CARRIERS

where:
K1: Coefficient defined in [2.7.2]

θ 1 θ h : Angle, in deg, between inner bottom plate and bilge hopper sloping plate or inner hull plateingθ2: Single roll amplitude, in deg, defined in Ch 4, Sec 2, [2.1]aY: Transverse acceleration, in m/s2, defined in Ch 4, Sec2, [3.2]⎞⎛yG _ scahopper = −CYR a R sin ⎜ tan −1− θ h ⎟ + g cos(θ h − CYGθ ) cos(C XG Φ ) + CYS a sway sin θ h
⎟
⎜
R
⎠
⎝

aR

: tangential acceleration defined in [2.7.1 bis1].

asway: Transverse acceleration due to sway, in m/s2, defined in Ch 4, Sec 2, [2.4]

CXG, CYS, CYR, CYG: Load combination factors defined in Ch 4, Sec 4, [2.2]yG_sc: Centre of gravity in transverse direction, in m, defined in [2.7.1 bis1]

R: Coefficient defined in Ch 4 Sec 2, [3.2.1]

F′: Force, in kg, taken equal to:F′ =Wn 2 C kn3

F ' = CkW

λP

l
lS

for n 2 ≤ 10 and n3 ≤ 5

for n 2 > 10 or n3 > 5 ,: Coefficient defined in Tab 6

W, n2, n3, Φ and θ : As defined in [2.7.2]
Ck: Coefficient taken equal to:
Ck = 4.03.2 when steel coils are lined up two or more tier, or when steel coils are lined up one tierand key coil is located second or third from bilge hopper sloping plate or inner hull plate
Ck = 2.52.0 for other cases
Steel coil

Dunnage

Inner bottom

n2 and ℓ’ are given by
Tables 3 and 4

Floor

BottomFigure 3: Loading condition of steel coils (Example of n 2 = 4 , n3 = 3 )PAGE 46 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-3
Steel coil

Dunnage

Inner bottom

ℓ'
Floor

BottomFigure 4: Loading condition of steel coils (Example of n 2 = 3 , n3 = 3 )2.7.4
Where the number of load points per elementary plate panel n2 is greater than 10 and/or the number of dunnages

n3 is greater than 5, the inner bottom may be considered as loaded by a uniform distributed load. In such a case,the thickness of the inner bottom plating is to be obtained according to [3.2.1]. (void)

PAGE 47 OF 171

RULE CHANGE NOTICE NO.1-3

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 3: Number n2 of load points per elementary plate paneln2n3 = 2l≤ 0.5
lS

n3 = 30<l≤ 0.33
lS

1

0<

2

0.5 <

l
≤ 1.2
lS

0.33 <

3

1.2 <

l
≤ 1.7
lS

0.67 <

4

1.7 <

l
≤ 2.4
lS

5

2.4 <

6

n3 = 40<l≤ 0.25lSl≤ 0.67lS

0.25 <

l
≤ 1.2
lS

0.5 <

1.2 <

l
≤ 1.53lS

0.75 <

l≤ 2.9
lS

1.53 <

l≤ 1.87
lS

1.2 <

2.9 <

l
≤ 3.6
lS

1.87 <

l≤ 2.4
lS

1.45 <

7

3.6 <

l
≤ 4.1
lS

2.4 <

l
≤ 2.73
lS

1.7 <

8

4.1 <

l
≤ 4.8
lS

2.73 <

l≤ 3.07lS

1.95 <

9

4.8 <

l
≤ 5.3
lS

3.07 <

l
≤ 3.6
lS

2.4 <

10

5.3 <

l
≤ 6.0
lS

3.6 <

l
≤ 3.93lS

2.65 <

n3 = 5
0<

l
≤ 0.2
lS

l
≤ 0.5
lS

0.2 <

l
≤ 0.4
lS

l
≤ 0.75
lS

0.4 <

l
≤ 0.6
lS

l
≤ 1.2
lS

0.6 <

l
≤ 0.8
lS

l
≤ 1.45
lS

0.8 <

l
≤ 1.2
lS

l
≤ 1.7
lS

1.2 <

l
≤ 1.4
lS

l
≤ 1.95
lS

1.4 <

l
≤ 1.6
lS

l
≤ 2.4
lS

1.6 <

l
≤ 1.8
lS

l
≤ 2.65
lS

1.8 <

l
≤ 2.0
lS

l
≤ 2.9
lS

2.0 <

l
≤ 2.4
lS

Table 4: Distance between load points in ship length direction
per elementary plate panel of inner bottom
n2
1
2
3
4
5
6
7
8
9
10

n3
2
3
Actual breadth of dunnage
0.5lS
0.33lS
1.2lS
0.67lS
1.7lS
1.20lS
2.4lS
1.53lS
2.9lS
1.87lS
3.6lS
2.40lS
4.1lS
2.73lS
4.8lS
3.07lS
5.3lS
3.60lS

PAGE 48 OF 171

450.25lS
0.50lS
0.75lS
1.20lS
1.45lS
1.70lS
1.95lS
2.40lS
2.65lS

0.2lS
0.4lS
0.6lS
0.8lS
1.2lS
1.4lS
1.6lS
1.8lS
2.0lS

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-3

Section 2 ORDINARY STIFFENERS

2. General requirements
2.5 Ordinary stiffeners of inner bottom loaded by steel coils on a wooden
support2.5.1 General
The requirements of this sub-article apply to the ordinary stiffeners located on inner bottom plate, bilge hopper

sloping plate and inner hull plate when loaded by steel coils on a wooden support (dunnage), as indicated in Fig
2 of Ch 6, Sec 1.
In case where steel coils are lined up two or more tier, formulae in [2.5.2] and [2.5.3] can be applied to the casethat only lowest tier of steel coils is in contact with hopper sloping plate or inner hull plate. In other cases,
scantlings of net section modulus and net shear section area are calculated by direct strength analysis or otherprocedures.
2.5.2 Ordinary stiffeners located on inner bottom plating
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of single span ordinary stiffeners

located on inner bottom plating are to be not less than the values obtained from the following formulae:
w = K38λ S RY

5(g + a Z )F −3
10τ a sin φ

Ash =w = K3Ash =(g + a Z )F

[g ⋅ cos(C ZP Φ )⋅ cos(C ZRθ ) + a Z ]⋅ F
8 ⋅ λ S RY

5[g ⋅ cos(C ZP Φ ) ⋅ cos(C ZR θ )) + a Z ]⋅ F −310
τ a sin φwhere:
K3: Coefficient defined in Tab 1. When n 2 is greater than 10, K 3 is to be taken equal to 2l/3

aZ

: Vertical acceleration, in m/s2, defined in Ch 4, Sec2, [3.2] Ch 6, Sec 1, [2.7.1 bis1]

Φ: Single pitch amplitude, in deg, defined in Ch 4, Sec 2, [2.2]θ: Single roll amplitude, in deg, defined in Ch 4, Sec 2, [2.1]

CZP,CZR : Load combination factor defined in Ch 4, Sec 4, [2.2]F: Force, in kg, defined in Ch 6, Sec 1, [2.7.2]

λS: Coefficient defined in Tab 3

φ: Angle, in deg, defined in [3.2.3].

PAGE 49 OF 171

RULE CHANGE NOTICE NO.1-3
2.5.3

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Ordinary stiffeners located on bilge hopper sloping plate or inner hull plateing

The net section modulus w , in cm3, and the net shear sectional area Ash , in cm2, of single span ordinary
stiffeners located on bilge hopper sloping plate and inner hull plate are to be not less than the values obtained
from the following formulae:[g cos(θ1 − θ 2 ) + aY sin θ1 ]F 'w = K3Ash =8λ S RY

5aY F '10 −3
τ a sin ϕ sin φa hopper F 'w = K3Ash =8λ S RY

5a hopper F 'τ a sin φ

10 −3

where:
K3: Coefficient defined in Tab 1. When n 2 > 10 , K 3 is taken equal to 2l/3.

θ1, θ2: Angles, in deg, defined in Ch 6, Sec 1, [2.7.3]

θh: Angle, in deg, between inner bottom plate and bilge hopper sloping plate or inner hull plateaY: Transverse acceleration, in m/s2, defined in Ch 4, Sec 2, [3.2]

a hopper : Acceleration, in m/s2, defined in Ch 6 Sec 1, [2.7.3]
F': Force, in kg, defined in Ch 6, Sec 1, [2.7.3]

λS: Coefficient defined in Tab 3

φ: Angle, in deg, defined in [3.2.3]

φ: Angle, in deg, between inner bottom plating and hopper sloping plate or inner hull plating.

l': Distance, in m, between load points per elementary plate panel of inner bottom plate in ship length,
sloping plate or inner hull plating, as defined in Ch 6, Sec 1, [2.7.2].

l′: Distance, in m, between outermost load points per elementary plate panel in ship length
Table 1 : Coefficient K3

n2
K3

1
l

2
l−

3
'2

l
l

l−

4
'2

2l
3l

l−

6

5
'2

5l
9l

l−

'2

l
2l

l−

7
'2

7l
15l

l−

8
'2

4l
9l

l−

9
'2

3l
7l

l−

10
'2

5l
12l

l−

11l ' 227l

2.5.4

Where the number of load points per elementary plate panel n2 is greater than 10 and/or the number of dunnages
n3 is greater than 5, the inner bottom may be considered as loaded by a uniform distributed load. In such a case,the scantling of the inner bottom ordinary stiffeners is to be obtained according to [3.2.3]. (void)

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-3(Steel Coil)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are, individuallyand collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individually and collectively,
assume no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on theinformation or advice in this document or howsoever provided, unless that person has signed a contract with therelevant IACS Member entity for the provision of this information or advice and in that case any responsibility or
liability is exclusively on the terms and conditions set out in that contract.

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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for the Change Regarding Scantling Formulafor Steel Coil Loading
1. Background of Rule change regarding steel coil loading
1.1 Addition of GM and kr value for steel coil loading to the note of Table 1 in Ch 4, Sec 2,[2.1.1]
Roll radius of gyration ( k r ) and metacentric height ( GM ) in the considered loading condition isused for the calculation of the parameters regarding the ship’s absolute motion and accelerations.
When these values are not known, the default values specified in Table 1 in Ch 4, Sec 2, [2.1.1]
may be assumed in the current CSR.
However, these default values specified in the Table do not correspond to the steel coil loading
condition because the steel coil load is normally concentrated near the inner bottom.
The rule change is made to set the GM value based on the actual design values given in Table 1 andthe averaged values of GM and kr is about 0.24B and 0.42B, respectively.
Table 1 Actual GM Value

B
Actual GM
GM = X*B
B
Actual GM
GM = X*B
B
Actual GM
GM = X*B

32.26
8.05
0.245
27.00
6.88
0.255
23.50
4.95
0.211

32.26
7.76
0.241
26.00
6.38
0.245
22.30
4.65
0.209

31.00
8.34
0.269
23.50
4.95
0.211
27.00
6.89
0.255

29.40
7.99
0.272
24.50
5.78
0.236
27.00
6.93
0.257

23.00
4.39
0.191
24.40
4.93
0.202
32.26
9.30
0.288

19.60
4.12.
0.210
23.70
5.06
0.214
32.26
9.11
0.282

23.50
4.95
0.211
27.0
6.89
0.255
27.20
6.12
0.225

23.70
5.10
0.215
23.700
5.10
0.215
32.26
9.14
0.283

The GM and kr value for steel coil loading are newly added to Table 1 in Ch 4, Sec 2, [2.1.1] asa default value.
1.2 Modification of the requirements in Ch 6, Sec 1, [2.7.1] and Ch 6, Sec 2, [2.5.1]
The 3rd sentence and the 4th sentence in Ch 6, Sec 1, [2.7.1] and the 2nd sentence and the 3rd
sentence in Ch 6, Sec 2, [2.5.1] are deleted due to the following reasons.
(a) As the term of the acceleration in the scantling formula is revised in order to accommodate anyloading pattern of steel coil as mentioned in Annex 1, the limitation of the rule application
regarding the loading pattern is not necessary.
(b) In addition, CSR does not permit overruling the scantling determined by the prescriptive
requirement by FEA.
1.3 Clarification of the treatment of centre of gravity for steel coil loading
If the actual centre of gravity in steel coil loaded condition is known, it is better to use the actual
one in calculating the acceleration. Therefore, this treatment has been added to the text.
If the actual centre of gravity is not known, the standard value of the centre of gravity is needed.
Then the centre of gravity (x, y, z ) is set up mid − hold , εBh 4 , hDB + 1 + (n1 − 1) 3 2 d SC 2 as a

(

(

)

)

conservative manner, where Bh is defined as a breadth of the cargo hold and ε is 1.0 when a portside structural member is considered, or -1.0 when a starboard side structural member isconsidered.

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1.4 Amendment of the formulae for plating and ordinary stiffeners of inner bottom, bilge
hopper and inner hullIn the current formulae for inner bottom plating and ordinary stiffeners (inner bottom
longitudinals), load cases H and F are only considered but the load cases R and P is not considered.
The rule change is made to consider the all load cases.
The current formulae for plating and ordinary stiffeners of bilge hopper and inner hull give theexcessive scantling due to the account of gravity acceleration in duplicate and conservative
coefficient C k . In addition, formula for shear area of the ordinary stiffeners is modified.
1.5 Amendment of the treatment which the number of load points per elementary plate panel
is greater than 10 and/or the number of dunnages is greater than 5.
In the current requirements, the number of load points per elementary plate panel n 2 is greaterthan 10 and/or the number of dunnages n3 is greater than 5, the scantling of plating and ordinary
stiffeners may be checked by the formulae based on uniform distributed loads. However, thisassumption is inappropriate because the scantling formula for steel coil is based on the line load
which is transformed from the concentrated loads due to steel coil acting on the most severe
locations of an elementary plate panel. Even if the number of load points becomes larger than 10,
this assumption for the load model should be kept.
Therefore, the texts of Ch 6, Sec 1, [2.7.4] and Ch 6, Sec 2, [2.5.4] are deleted.
Furthermore, in order to clarify the treatment where the number of load points per elementary
plate panel is greater than 10 and/or the number of dunnages is greater than 5, the relevant text isrevised.
The technical backgrounds of these modifications are described in Annex 1.

2. Summary of Rule Changes
2.1 Ch 4, Sec 2, Table 1
The GM and kr values are added to Table 1 as averaged values based on the investigation resultsof actual ships’ data.
2.2 Ch 6, Sec 1, [2.7.1]
The 3rd and the 4th sentences are deleted.
2.3 Ch 6, Sec 1, [2.7.2], [2.7.3], [2.7.4]
The new paragraph [2.7.1 bis1] is added for calculating the acceleration and the paragraph [2.7.4]
is deleted. The tangential acceleration due to roll is added.

aR = θ

π ⎛ 2π ⎞⎜⎟180 ⎜⎝ TR ⎟⎠Where,

22y SC + R 2

yG_SC: Centre of gravity in transverse direction, in m, is taken equal to yG − sc = ε

Bh4

R: Coefficient defined in Ch 4 Sec 2, [3.2.1] of the Rules
TR: Roll period, in s, defined in Ch 4, Sec 2, [2.1.1] of the Rules
Bh: breadth in m, at the mid of the hold.
In order to consider the acceleration of pitch, although the effect is very small because the holdlength is relative short, the definition of xG_SC is added as follows.
xG − sc = 0.75 l forward of aft bulkhead, where the hold of which the mid position is located forwardHfrom 0,45L from A.E.

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COMMON STRUCTURAL RULES FOR BULK CARRIERS

xG − sc = 0.75l afterward of fore bulkhead, where the hold of which the mid position is locatedHafterward from 0,45L from A.E
The backgrounds of these modifications are described in Annex 1
2.4 Ch 6, Sec 1, [2.7.2]
The scantling formula for load cases H and F is revised in order to consider all load cases. In
addition, the interpretation of the case where n2>10 or n3>5 is added.
t = K1{g (cos(CZP Φ ) ⋅ cos(CZRθ )) + az }F
λP RY

Where,
Wn1n 2n3

For n2<=10 and n3<=5,

F = KSFor n2>10 or n3>5

F = K S n1WllS

Definitions of all symbols are specified in the Rule text.
2.5 Ch 6, Sec 1, [2.7.3]
In the current formula, the gravity component is accounted in duplicate because the acceleration“ay” contains the component of gravity acceleration. The formula is corrected to consider thegravity acceleration component correctly and to correspond to the all load case. In addition, thecoefficient ck is changed based on the experimental data.
t = K1

a hopper F 'λ p RyWhere,For n2<=10 and n3<=5,
For n2>10 or n3>5

Wn2Ck
n3
l
F ' = CkW
lS
F '=

⎛
⎞
y G _ SC− θ h ⎟⎟ + g cos(ϑh − CYGθ ) cos(C XG Φ ) + CYS a sway sin θ ha hopper = −CYR a R sin ⎜⎜ tan −1
R⎝⎠
Definitions of all symbols are specified in the Rule text.
2.6 Ch 6, Sec 1, [2.7.4]
As the interpretation of the cases where n2>10 and/or n3>5 are added to the renumberedparagraph [2.7.3], the paragraph [2.7.4] is deleted.
2.7 Ch 6, Sec 2, [2.5.1]
The 2nd and the 3rd sentences are deleted.
2.8 Ch 6, Sec 2, [2.5.2] and [2.5.3]
The formulae for all load cases are provided as similar to the revision of the scantling formula for
plating in Ch 6 Sec 1.
2.9 Ch 6, Sec 2, [2.5.4]
As the interpretation of the cases where n2>10 and/or n3>5 are added to the paragraph [2.5.3], thisparagraph is deleted.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

3. Scantling impact due to modifications
For scantling of inner bottom plating and ordinary stiffeners there is less impact due to thismodification.
For thickness of bilge hopper sloping plate and inner hull plate and section modulus of ordinary
stiffeners, the conservative scantling required by the current requirement is improved by thismodification.
Details of the calculation for scantling impact due to these modifications are described in Annex
2.

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COMMON STRUCTURAL RULES FOR BULK CARRIERS

Annex 1: Background of the formulae for steel coil loading
Ch 6, Sec 1
2.7 Inner bottom loaded by steel coils on a wooden support
2.7.1 General
2.7.1a In dimensioning the plating and ordinary stiffeners, static and dynamic loads due to dry
bulk cargoes and liquid acting on the plating and ordinary stiffeners are considered as
uniformly distributed loads. On the other hand, as steel coils are loaded on a wooden
support (dunnage) provided on the inner bottom plating and bilge hopper plating, theconcentrated loads due to steel coils act on the plating through the dunnage. However,as the location of concentrated loads and the distance between concentrated loads
depend on the loading pattern and size of dunnage, it is assumed that the concentrated
load is transformed to a line load with a small breadth (hereinafter referred to as“rectangular load”) which acts on the most severe conditions (load point and distance
between load points). Based on this assumption, the specific formulae fordimensioning the plating and ordinary stiffeners under steel coil loading are introducedin the Rules separately from those based on uniformly distributed loads.
2.7.1b The specific requirements for plating are specified in Ch 6 Sec 1 [2.7.2] and [2.7.3],
and those for ordinary stiffeners are specified in Ch 6 Sec 2 [2.5.2] and [2.5.4].
2.7.1c The technical background of loads due to steel coils is common for plating andordinary stiffeners.
2.7.1d These requirements are based on the assumption that steel coils are loaded on awooden support and secured in the standard manner. These assumptions are given in
Figure 2 in Ch 6 Sec 1.
2.7.2 Inner bottom plating
2.7.2a Load model
Steel coils are usually secured to each other by means of steel wires. Heavier steel coils
are loaded with one or two tiers, and lighter ones are loaded with two or more tiers.
Examples of steel coil loading are shown in Figs.1 and 2.

key coilBilge hopper
sloping plating

Bilge hopper
sloping plating

Inner bottom plating(A) with key coil

Inner bottom plating(B) without key coilFig.1 Loading conditions of one tierBilge hopper
sloping plating
Inner bottom plating

Fig.2 Loading conditions of two tiers

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The load due to steel coils acts on an elementary plate panel as a concentrated load
through dunnages. However, it is difficult to treat concentrated loads directly because
the location of concentrated loads and the distance between concentrated loads dependon the loading pattern and size of dunnage. Then, the following assumptions regarding
the loads due to steel coils are considered.
(1) Loads due to steel coils act along a centreline of a plate panel.
(2) A rectangular load instead of concentrated loads is used in order to be on the safer
side considering the interaction between concentrated loads.
Steel coilz

Inner bottom plating

l
x
Floor

y

s

Floor

dunnage

Elementary plate panel

l'

l

l

x

Fig.3 Convert concentrated loads to rectangular loads
As it is the most severe when loads act on the inner bottom vertically, the verticalacceleration is considered for the scantling formula of inner bottom structures. The
position of the centre of gravity is given by the following.
x direction: (i) for the hold of which the mid position is located forward of 0.45L from A.E.: XG_SC =0.75 lH forward of aft bulkhead, and (ii) for the hold of which the mid position is located afterward of
0.45L from A.E.: XG_SC= 0.75 lH afterward of fore bulkhead, where lH is a cargo hold length
y direction: εBh 4 , measured from the centreline()

z direction: h DB + 1 + (n − 1) 3 2 d SC 2

Where,d SC : The diameter, in m, of steel coilh DB : The height, in m, of double bottom
Bh: breadth, in m, at the mid of the hold

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COMMON STRUCTURAL RULES FOR BULK CARRIERS

2 3 dSC
2
3 dSC
2

dSC
2
hDB

dSC
2
Inner bottom
plating

hDB

Bottom plating

Fig.4 The height of steel coils
2.7.2b Structural model

As mentioned in 2.7.2a, the rectangular load acts along the centreline of the panel. Its
length l ' is determined by the panel length l , the length of a steel coil l S , the number ofload points n 2 and the number of dunnages supporting one steel coil n3 , and its width
0.3s is derived from dunnage width based on the actual loading data. Of course, theaxial stress due to hull girder bending is considered in addition to the lateral rectangularload due to the steel coils. An elementary plate panel is collapsed like Fig.5. The
boundary conditions of an elementary plate panel are that all sides are considered fixed.
l

0.3s

s
l'

Fig.5 Rectangular load and collapsed mode
2.7.2c Number of load points and distances between load points in ship length direction perelementary plate panel

Tables 3 and 4 in Ch 6, Sec 1 of the Rules give the standard number of load points anddistances between load points in ship length direction for the case of n 2 ≤ 10 and/or
n3 ≤ 5 . For other cases, the current treatment as noted in Ch 6, Sec 1, [2.7.4] stipulates
that loads due to steel coils are considered as a uniform distribution load and thescantling of plating is obtained according to Ch 6, Sec 1, [3.2.1]. However, it isconsidered that the scantlings of plating and ordinary stiffeners under steel coil loads
are treated separately from those for distributed loads. Therefore, the instruction in Ch
6, Sec 1, [2.7.4] is not appropriate and it has been deleted. Instead a line load at panel
centreline is assumed throughout the panel length.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

The calculation results are shown in Table 1. In this calculation, the coefficient n3 ischanged from 3 to 6, the coefficient n 2 is derived from the same procedure gotten from
Tables 3 and 4 in Ch 6, Sec 1 of the Rules.
The calculation results according to the generic formula for plating and ordinary
stiffener specified in Ch 6, Sec 1, [3.2.1] and Sec 2, [3.2.3] of the Rules are calculated
by assuming that the loads due to steel coils are treated as uniformly distributed loads
defined as (Wl/ls).
It is found from this result that the required net thickness and net section modulus foruniform load is greater than those for load model specified in the Rules. In order toeliminate this difference between the case of n2>10 and/or n3>5 and the case of n2<=10
and n3<=5, the treatment of the case n2>10 and/or n3>5 is added to the Rules andcurrent paragraphs [2.7.4] of Ch 6 Sec 1 and [2.5.4] of Ch 6, Sec 2 are deleted.

l (m)
s (m)
n1
n2
n3
ls (m)l’ (m)W (kg)F (kg)
tnet_req (mm)wnet_req (cm3)

Table 1 Comparison of required scantlings
Line load according to Ch 6, Sec 1, [2.7.2] and Uniform load according
Sec 2, [2.5.2]
to Ch 6, Sec 1, [3.2.1]
2.4
2.4
2.4
2.4
2.4
0.8
0.8
0.8
0.8
0.8
2
2
2
2
5
6
7
9
3
4
5
6
1.5
1.5
1.5
1.5
1.53 11.45 11.40 11.53 1
15000
15000
15000
15000
50000
45000
42000
45000
45000(n2=6)
15.8
15.4
15.0
15.0
17.5
391
400
399
401
432

2.7.2d Coefficient KS

When steel coils are lined up in one tier with a key coil as shown in Fig.1 (A), twocoils support a key coil. However, it is known that half of the weight of a key coil does
not act on the supporting coil due to the frictional resistance between steel coils. In
order to investigate the effect of the frictional resistance between steel coils,
parametric experiments were carried out by the Shipbuilding Research Association ofJapan.
If the force due to steel coils is expressed by the following formula, the effect offrictional resistance ( K S ) is given in Table 2.
Wn1 n 2
F = KS
n3
Where,
W : Mass of one steel coil, in kg
n1 : Number of tier of steel coilsn 2 : Number of load points per elementary paneln : Number of dunnages supporting steel coil

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Table 2 Coefficient K S derived from experiments results
Position of
key coil (m-n)
3-3
3-6

1/2
1.40
1.36

a/D
1/3
1.36
1.41

1/6
1.34
1.43

This result shows that the effect of the frictional resistance depends on the diameter ofsteel coils and distance between the centres of coils. The average value is 1.38, andtherefore K S is taken to equal to 1.4 to be on the safe side.
2.7.2e Coefficient K1 and K2
The coefficients K 1 and K 2 are derived from the principle of virtual work based onmaterial physics.
2.7.2f Formula for required thickness of inner bottom plating
Finally, the scantling formula for inner bottom plating is given as follows.
{g (cos(C ZP Φ )cos(C ZRθ )) + a z }F
t = K1λP RY

Where,
Wn1n 2n3

For n2<=10 and n3<=5,

F = KSFor n2>10 or n3>5

F = K S n1WllS

2.7.3 Bilge hopper sloping plate and inner hull plate
2.7.3a Load model

The load model for hopper sloping and inner hull plating is very complex because theloads are supported by the inner bottom directly or by other steel coils as shown in Fig.6.

Inner hull
plating

Bilge hopper
sloping plating
Inner bottom plating

Inner bottom plating

Fig.6 The examples of steel coil loading conditions
The force due to steel coils for bilge hopper sloping plate and inner hull plate isexpressed by the following formula considering the effect of frictional resistance
between steel coils and the support by the inner bottom.
Wn2 C kF'=
n3
Where,
W , n 2 and n3 are specified in 2.7.2d.
C k : The coefficient specified in 2.7.3c.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

This load model is the same for the inner bottom. Although the vertical component of theload is supported by the inner bottom directly or by other coils, only Ck is considered toderive the loads acting on the side wall.
As specified in 2.7.3c, the coefficient Ck is introduced based on the experiments. Thiscoefficient Ck is based on the component of the load in the transverse direction.
Therefore, the component of the load in transverse direction is only considered in the
scantling formula for bilge hopper plate and inner hull plate.
In the original formula specified in the current Rule text, it was considered that theequivalent design wave (EDW) “R” was dominant in the bilge hopper sloping plate or
inner hull plate. However, as the acceleration in transverse direction specified in Ch 4
Sec 2, [3.2.1] includes the static component due to roll angle, the static component due togravity acceleration is counted in duplicate. Therefore, the term related to the transverse
acceleration in scantling formula for load case R is revised.
In addition, in order to cover all load cases, the term related to the acceleration in the
scantling formula is revised as follows, considering the load combination factors.
⎛⎞
y G _ SC− θ h ⎟⎟ + g cos(θ h − CYGθ ) cos(C XG Φ ) + CYS a sway sin θ ha hopper = −CYR a R sin ⎜⎜ tan −1
R⎝⎠
Where:
2
a roll y asway : Acceleration due to roll and sway, in m/s , defined in Ch.4 Sec.2 [3.2]2

a R : Tangential roll acceleration, in m/s . (See Fig. 7)2
π ⎛ 2π ⎞2⎜⎟aR = θ
y G − sc + R 2⎜⎟
180 ⎝ TR ⎠y G − sc : Centre of gravity of steel coils in transverse direction, in m. (see Fig, 7)
R : Coefficient defined in Ch. 4 Sec. 2 [3.2.1]. (see Fig.7)
TR : Roll period, in s, defined in Ch 4, Sec 2, [2.1]2

g : Gravity acceleration, in m/s

θ h : Angle, in degrees, between inner bottom plating and bilge hopper sloping plate or
inner hull plate. (see Fig. 7)
θ : Single roll amplitude, in degrees, defined in Ch 4, Sec 2, [2.1]
CYG, CYR, CYS, CXG: Load combination factors defined in Ch 4, Sec 4, [2.2]

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COMMON STRUCTURAL RULES FOR BULK CARRIERS

θh
yG-sc

R

aR

θh
CL
Centre of gravity

Fig.7 Definition of the acceleration aR
2.7.3b Structural model

The structural model for bilge hopper sloping plating and inner hull plating is the samefor inner bottom plating.
2.7.3c Coefficient Ck

In order to determine the coefficient C k specified in 2.7.3a, experiments were
performed by the Shipbuilding Research Association of Japan. According to the report,
the experiments were carried out under the following conditions specified in (a) to (d)and as shown in Fig.8.
m

Key coiln

Dunnage

Side shell
Strain gaugeaD

Note: m and n is the number of coils counted from the key coil.
Fig.8 Experiment device and loading condition of steel coils
(a)
(b)
(c)
(d)

Steel coils were loaded with one tier with key coilRoll angle was 20 degree
Roll period was 60 seconds
Position of key coil was changed (“m” in Fig.8 was changed from 1 to 8)

In addition, a theoretical analysis was tried and the results are shown in Fig. 9.
According to the results shown in Fig. 9, the following outcomes were obtained.
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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3i) The Ck value is obtained from the loads on side wall based on the force in transverse
direction.
ii) The C k value strongly depends on the location of the key coil.
iii) The effect of the diameter of steel coils and the length between the gravity centre ofsteel coils is relatively small compared to the effect of the location of the key coil.
iv) The calculation results match the experimental results well.
v) In order to be on the safe side, C k = 3.2 is an appropriate value when the key coil islocated second or third from the side shell and C k = 2.0 is appropriate in other cases.
Ck :Coefficient taken to equal:
C k = 3.2 when steel coils are lined up in two or more tiers, or steel coils are lined up
in one tier and the key coil is located second or third from the bilge hopper
sloping plating or inner hull plating
C k = 2 .0
for other cases
3.2

Ck

Roll angle = 20 (deg)Calculation

m-n

Fig.9 Experimental results
2.7.4
2.7.4a The current text is deleted.

Ch 6, Sec 2
2.5 Ordinary stiffeners of inner bottom loaded with steel coils on a wooden support
2.5.1 General
2.5.1a Same as specified in 2.7 for plating.

2.5.2 Ordinary stiffeners located on inner bottom plating
2.5.2a Load model
As the structural model for plating is based on the plastic theory, it is too complex totreat the concentrated load. Therefore, a rectangular load is considered in therequirement for plating mentioned in Ch 6, Sec 1, [2.7.2].
On the other hand, the structural model for ordinary stiffeners is based on the simple
elastic beam theory. Therefore, the load model for ordinary stiffeners is based on
concentrated loads due to steel coils acting through the dunnage.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSThe calculation of acceleration is based on the same assumption for plating.
The parameter and coefficients are also the same for plating.
According to the similar reason specified in 2.7.2c, Ch 6, Sec 2, [2.5.4] has been
deleted.
2.5.2b Structural model
Structural model of ordinary stiffeners is based on the simple beam theory with theboundary condition that both ends of beams are fixed.
2.5.2c Coefficient K3
The coefficient K 3 is derived from the ratios of moments at ends of ordinary stiffeners
against n 2 = 1 when load points of the concentrated loads are located evenly between l 'as shown in Fig.10 When n 2 is over 10, the coefficient K 3 is 2/3.
P

P/2

P/2

l'
n2=2

n2=1
P/3

P/3

P/3

P/4

P/4

P/4

l'

l'

n2=3

n2=4

P/4

Fig.10 Load points on an ordinary stiffener
2.5.3 Ordinary stiffeners located on hopper sloping plate or inner hull plating
2.5.3a Load model
The concentrated load is considered as specified in 2.5.2a and the acceleration due toroll motion is considered as specified in 2.7.3a of Ch 6, Sec 1.
2.5.3b Structural model
Structural model of an ordinary stiffener is specified in 2.5.2b.
2.5.4
2.5.4a This item is deleted.

PAGE 64 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

Annex 2: Scantling impact due to modifications
Ramification studies
In order to quantify the impact due to the modification of the scantling formula for plating
and ordinary stiffeners, ramification studies were performed using the following 6 ships listed
in Table 2-1.
The data of the steel coils listed in Table 2-2 taken from the loading manuals of theconsidered ships was used for the ramification study.

Ship 1
Handy max

W (kg)l S (m)Number of tiers
Key coil

Table 2-1 Principal dimensions of subject ships
Pre-CSR ship
CSR ship
Ship 2
Ship 3
Ship 4
Ship 5
Ship 6
Small
Small Handymax Handymax
Handy
Table 2-2 Data of steel coils
Ship 1
Ship 2
Ship 3
15000
20000
15000
1.5
1.8
1.5
2
1
1
not used
used
used

Ship 420000
1.5

Ship 515000
1.5Ship 615000
1.5

2
Not used2
Not used2
Not used

1. Scantling changes at inner bottom structures
Where the number of load points is not greater than 10 and/or number of dunnages is not
greater than 5, the scantling formulae for inner bottom plating and ordinary stiffeners are notchanged by the Rule Change proposal 3. However, as the calculation point of acceleration ismodified and the default value of GM and k r are newly added, the scantling impact
calculations were carried out in order to grasp the changes.
Calculation results are shown in Figs.2-1 to 2-3. These results show that the required
scantlings are not that different between the current CSR and the modification because thevertical acceleration in EDW “H” which is dominant for the scantlings of inner bottom plating
and longitudinals is not affected by the y- and z- coordinate of the gravity centre.
For reference, the required thickness of inner bottom plating was increased by 3 to 4mm
compared to that of pre-CSR designs because the corrosion additions specified in CSR arelarger by 3 to 4 mm than those used in Pre-CSR designs.
Regarding inner bottom longitudinals, the difference between the required section
modulus and the actual one of pre-CSR designs varies largely depending on the design.
The required shear area is smaller than the actual one of pre-CSR designs.
On the other hand, as the offered scantlings of inner bottom structure for CSR design
ships are greater than those determined by the requirement for steel coil loading, they may be
determined by the requirement other than that for steel coil loading.
Therefore, there is no scantling impact for inner bottom plate and longitudinals due to hischange.

2. Scantling changes at bilge hopper and inner hull structures
2.1 Scantlings of plating
Required gross thicknesses of bilge hopper sloping plating are shown in Fig.2-4. This
figure shows that the modification improves the formula by providing the appropriate
thickness compared to that of inner bottom plating.
PAGE 65 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor reference, the required thicknesses of bilge hopper sloping plating was increased by
3 to 4mm compared to those of pre-CSR designs because the corrosion additions specified in
CSR are larger by 3 to 4mm than those used in the pre-CSR designs.
For CSR ships, the thicknesses of bilge hopper plating are determined by therequirement for steel coil loading, but, the scantling of longitudinal attached to the hopper
sloping plate may be determined by the requirement other than that for steel coil loading. As
a result, only thickness of hopper sloping plate according to the proposed formula becomesthat similar to inner bottom plating and decreased about 4mm for these example cases.
If the thicknesses of hopper sloping plate would be determined by the proposed
requirement for steel coil loading, the total steel weight is decreased about 20 tons for ship 5
and 15 tons for ship 6 by this change.
2.2 Scantlings of ordinary stiffeners
2.2.1 Section modulus
Required net section moduli of ordinary stiffeners attached to bilge hopper sloping
plating are shown in Fig. 2-5. This figure shows that the modification improves the formulaby providing the appropriate section modulus compared to that of inner bottom longitudinals.
Regarding the bilge hopper longitudinal, the difference between the required section
modulus and actual one of Pre-CSR designs varies largely depending on the design.
For CSR ships, the scantlings of longitudinal attached to hopper sloping plate become
about 60% of those required current rules in terms of section modulus by this change.
Therefore, the final scantlings of the longitudinal may be determined by other requirements.
If the scantling of longitudinals would be determined by the proposed formula, the steel
weight will be decreased about 4 tons for ship 5 and 2 tons for ship 6 by this change.
2.2.2 Section area
Required net section areas of ordinary stiffeners fitted to the bilge hopper sloping plating
are shown in Fig.2-6. The required section area according to modified formulae is larger thanthose of current CSR. This increase is caused by the correction of a mistake in the formula.
For reference, the required shear area according to the modified formula is smaller than
the actual one of both pre-CSR designs and CSR ships.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

30

ActualCSR
Modification

Gross Thickness (mm)

25

20

15

10

5

0

Ship 1

Ship 2

Ship 3

Ship 4

Ship 5

Ship 6

Fig.2-1 Comparison of gross thickness of inner bottom plate
1200

ActualCSR
Modification

Net Section Modulus (cm3)

1000

800

600

400

200

0

Ship 1

Ship 2

Ship 3

Ship 4

Ship 5

Ship 6

Fig. 2-2 Comparison of net section moduli of inner bottom longitudinals

PAGE 67 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

COMMON STRUCTURAL RULES FOR BULK CARRIERS

50

ActualCSR
Modification

45

2

Net Section Area (cm )

40
35
30
25
20
15
10
5
0

Ship 1

Ship 2

Ship 3

Ship 4

Ship 5

Ship 6

Fig.2-3 Comparison of net section area of inner bottom longitudinals
40

ActualCSR
Modification

35

Gross Thickness (mm)

30
25
20
15
10
5
0

Ship 1

Ship 2

Ship 3

Ship 4

Ship 5

Fig. 2-4 Comparison of gross thickness of bilge hopper sloping plate

PAGE 68 OF 171

Ship 6

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

1200

ActualCSR
Modification

3

Net Section Modulus (cm )

1000

800

600

400

200

0

Ship 1

Ship 2

Ship 3

Ship 4

Ship 5

Ship 6

Fig.2-5 Comparison of net section moduli of longitudinals attached to bilge hopper sloping
plate

50

ActualCSR
Modification

45

2

Net Section Area (cm )

40
35
30
25
20
15
10
5
0

Ship 1

Ship 2

Ship 3

Ship 4

Ship 5

Ship 6

Fig.2-6 Comparison of net section area of longitudinals attached to bilge hopper sloping plate

PAGE 69 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-3

PAGE 70 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSCOMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-4(Minimum Scantling, Side Frame
and Grab)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 71 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-4.

Chapter 6 HULL SCANTLING

Section 2 ORDINARY STIFFENERS
2. General requirements
2.2 Minimum nNet thicknesses of webs of ordinary stiffeners
2.2.1 Minimum net thicknesses of webs of oOrdinary stiffeners other than side frames ofsingle side bulk carriers
The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:•t = 3.0 + 0.015L2•

40% of the net required offered thickness of the attached plating, to be determined according to Ch.6, Sec.1.

and is to be less than 2 times the net offered thickness of the attached plating
2.2.2 Minimum net thicknesses of sSide frames of single side bulk carriers
The net thickness of side frame webs within the cargo area, in mm, is to be not less than the value obtained fromthe following formula:tMIN = 0.75α (7 + 0.03L)
where:
α: Coefficient taken equal to:
α = 1.15 for the frame webs in way of the foremost hold

α = 1.00 for the frame webs in way of other holds.
2.2.3 Maximum net thickness of web of ordinary stiffener
The net thickness of the web of ordinary stiffeners, in mm, is to be less than 2 times the net offered thickness of
the attached plating.

3. Yielding check3.3 Strength criteria for side frames of single side bulk carriers
3.3.1 Net section modulus and net shear sectional area of side frames
The net section modulus w, in cm3, and the net shear sectional area Ash , in cm2, of side frames subjected tolateral pressure are to be not less, in the mid-span area, than the values obtained from the following formulae:
w = 1.125α m( p S + pW )sl 2
mλ S RY

10 3

PAGE 72 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSAsh = 1.1α S

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-45( p S + pW )sl ⎛ l − 2l B ⎞⎜⎟τ a sin φ ⎝ l ⎠where:

αm: Coefficient taken equal to:αm = 0.42

for BC-A ships

αm = 0.36

for other ships

λS: Coefficient taken equal to 0.9l: Side frame span, in m, defined in Ch 3, Sec 6, Fig 19, to be taken not less than 0.25D

αS: Coefficient taken equal to:αS = 1.1

for side frames of holds specified to be empty in BC-A ships

αS = 1.0

for other side frameslB: Lower bracket length, in m, defined in Fig 7

ps, pw: Still water and wave pressures, in kN/m², in intact conditions calculated as defined in [1.3] and[1.4.2].

ll

Figure 7 Side frame lower bracket length

In addition to the above provision, for side frames of holds intended to carry ballast water in heavy ballast
condition, the net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, all along the span ofside frames subjected to lateral pressure in holds intended to carry ballast water are to be in accordance with
[3.2.3], l being the span of the side frame as defined in Ch.3 Sec.6 [4.2], with consideration to brackets at ends.
3.3.3 Lower bracket of side frame
In addition, aAt the level of lower bracket as shown in Ch 3, Sec 6, Fig 19, the net section modulus of the frameand bracket, or integral bracket, with associated shell plating, is to be not less than twice the net section modulus
w required for the frame mid-span area obtained from [3.3.1].
In addition, for holds intended to carry ballast water in heavy ballast condition, the net section modulus w, in
cm3, at the level of lower bracket is to be not less than twice the greater of the net sections moduli obtained from
[3.3.1] and [3.2.3].

PAGE 73 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

COMMON STRUCTURAL RULES FOR BULK CARRIERSThe net thickness tLB of the frame lower bracket, in mm, is to be not less than the net thickness of the side frame
web plus 1.5 mm.
Moreover, the net thickness tLB of the frame lower bracket is to comply with the following formula:h LB≤ 87 kt LB•

for symmetrically flanged frames:•

for asymmetrically flanged frames :h LB≤ 73 kt LB

The web depth hLB of lower bracket may be measured from the intersection between the sloped bulkhead of thehopper tank and the side shell plate, perpendicularly to the face plate of the lower bracket (see Ch 3, Sec 6,
Fig 22).
For the 3 side frames located immediately abaft the collision bulkhead, whose scantlings are increased according
to [3.3.2], when tLB is greater than 1.73tw, the thickness tLB may be taken as the value t’LB obtained from thefollowing formula:

(

2

'
t LB
= t LB t w

)

1

3

where tw is the net thickness of the side frame web, in mm, corresponding to Ash determined in accordance to[3.3.1].
The flange outstand is not to exceed 12k0.5 times the net flange thickness.
3.3.4 Upper bracket of side frame
In addition, aAt the level of upper bracket as shown in Ch 3, Sec 6, Fig 19, the net section modulus of the frameand bracket, or integral bracket, with associated shell plating, is to be not less than twice the net section modulus
w required for the frame mid-span area obtained from [3.3.1].
In addition, for holds intended to carry ballast water in heavy ballast condition, the net section modulus w, in
cm3, at the level of upper bracket is not to be less than twice the greater of the net sections moduli obtained from
[3.2.3] and [3.3.1].
The net thickness tUB of the frame upper bracket, in mm, is to be not less than the net thickness of the side frame
web.

PAGE 74 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

CHAPTER 9 OTHER STRUCTURES
Section 1 FORE PART

4. Scantlings
4.3 Ordinary stiffeners
4.3.3
The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:•t = 3.0 + 0.015L2•

40% of the net offered required thickness of the attached plating, to be determined according to [4.2] and[5.2].

and is to be less than twice the net offered thickness of the attached plating.
The net dimensions of ordinary stiffeners are to comply with the requirement in Ch 6, Sec 2, [2.2.2] and [2.3].

PAGE 75 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Section 2 AFT PART

4. Scantlings
4.2 Ordinary stiffeners
4.2.3
The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:•t = 3.0 + 0.015L2•

40% of the net offered required thickness of the attached plating, to be determined according to [4.1].

and is to be less than twice the net offered thickness of the attached plating.
The net dimensions of ordinary stiffeners are to comply with the requirement in Ch 6, Sec 2, [2.2.2] and [2.3].

PAGE 76 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

CHAPTER 12 ADDITIONAL CLASS NOTATIONS
Section 1 GRAB ADDITIONAL CLASS NOTATION

2. SCANTLINGS
2.1. Plating
2.1.1

The net thickness of plating of inner bottom, lower strake of hopper tank sloping plate, and transverse lower
stool plating, transverse bulkhead plating and inner hull up to a height of 3.0m above the lowest point of thefrom inner bottom, excluding bilge wells, is to be taken as the greater of the following values:•

t , as obtained according to requirements in Ch 6 and Ch 7•

tGR , as defined in [2.1.2] and [2.1.3].

2.1.2

The net thickness tGR, in mm, of the inner bottom plating is to be obtained from the following formula:t GR = 0.28(M GR + 50 ) sk

2.1.3

The net thickness tGR, in mm, within the lower 3 m of hopper tank sloping plate, and of transverse lower stool,transverse bulkhead plating and inner hull up to a height of 3.0m above the lowest point of the inner bottom,
excluding bilge wells, is to be obtained from the following formula:t GR = 0.28(M GR + 42 ) sk

PAGE 77 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

PAGE 78 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSCOMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-4(Minimum Scantling, Side Frame andGrab)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and inthat case any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 79 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for the Changes Regarding Scantling
Requirement for Ordinary stiffener, Side Frame and Grab
1. Reason for the Rule Change:
1.1 Ch 6, Sec 2, [2.2]
The current CSR requires the minimum thickness of webs of ordinary stiffeners is not tobe less than 40% of the net offered thickness of the attached plating. However, there are somecases where the thickness of plating is increased due to buckling check of the plating and hull
girder strength check and so on. In such cases, the thickness of web of ordinary stiffener isdetermined by the increased offered thickness of the attached plating and sometimes scantlingof the angle type stiffener is remarkable large in order to satisfy with this requirement. This
rule change is made to avoid such cases. (KC ID 213).

In addition, the maximum thickness of webs of ordinary stiffeners is mentioned in [2.2.1],
although the title of this requirement is minimum thickness requirement.
This requirement is based on the consideration of the proportion of thickness
between the attached plating and webs of ordinary stiffener. Accordingly, [2.2] will be
modified to be applicable both on minimum and maximum thickness, as follows:•
Title of [2.2] should be “Net thicknesses of webs of ordinary stiffeners”•
Title of [2.2.1] should be “Minimum net thicknesses of webs of ordinary stiffeners
other than side frames of single side bulk carriers”•
Title of [2.2.2] should be “Minimum net thicknesses of side frames of single side bulk
carriers”• New [2.2.3] with the following title: “Maximum net thickness of web of ordinary
stiffener”.

1.2 Ch 6 Sec 2, [3.3.1]
This change is made to clarify the requirement by specifying the extent of the span to use
and the calculation point for still water and wave pressures (refer to KC ID 216 and 217).
It specifies also that the requirements of Ch6. Sec2 [3.2.3] are to be asserted along the whole
span of the frames for holds intended to carry ballast water in heavy ballast condition (KC ID
356).
1.3 Ch 6 Sec 2, [3.3.3]
This change is made to clarify the requirement by specifying the requirements to be met
for side frame’s lower bracket in holds intended to carry ballast water in heavy ballast
condition (KC ID 356).
1.4 Ch 6 Sec 2, [3.3.4]
This change is made to clarify the requirement by specifying the requirements to be met
for side frame’s upper bracket in holds intended to carry ballast water in heavy ballast
condition (KC ID 356).
1.5 Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3]
The requirements in Ch 9 Sec 1, [4.3.3] and Sec 2 [4.2.3] are same required in Ch 6 Sec 2,[2.2.1].

PAGE 80 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

1.6 Ch 12 Sec 1, [2.1]This change is made to clarify the requirement by specifying the areas concerned by thiscalculation (refer to KC ID 313 and 544).

2. Summary of Rule Changes
2.1 Ch 6, Sec 2, [2.2.1], [2.2.3], Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3](1) The “net offered thickness” is changed to “net required thickness” and the required
thickness is determined according to Ch 6 Sec 1.
(2) The maximum net offered thickness is deleted from the requirement in [2.2.1] and theformula with the same meaning are added to new paragraph [2.2.3].
(3) The requirements in Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3] are revised in order to be same
for Ch 6 Sec 2, [2.2.1].
2.2 Ch 6, Sec 2, [3.3.1](1) The definition of the pressures for side frames is added.
(2) For side frames in ballast hold, the scantling check is carried out as an ordinary stiffenerwith span defined in Ch 3 Sec 6 [4.2].
2.3 Ch 6, Sec 2, [3.3.3] and [3.3.4]
For lower and upper brackets of side frame in ballast hold, the net section modulus at thelevel of brackets of side frame is to be not less than twice of the net section moduli obtainedby the requirements for both side frames and ordinary stiffeners.
2.4 Ch 12 Sec 1, [2.1]

Inner hull up to a height of 3.0m from the lowest point of inner bottom is applied to thisrequirement.

3. Impact on Scantling
3.1 Ch 6, Sec 2, [2.2.1], [2.2.3], Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3]

Regarding the minimum thickness requirement of webs of ordinary stiffeners, thescantling impact depends on the stiffener type used. If the angle type stiffener is used, thescantling is decrease by this change but steel weight decrease is negligible.
3.2 Ch 6 Sec 2 [3.3.1], [3.3.3] and [3.3.4]

There is no change in terms of the steel weight by comparing that before and after the
proposed Rule change.
3.3 Ch 12 Sec 1, [2.1]

For double side skin bulk carrier having the height of the bilge hopper tanks less than
3.0m or hybrid bulk carrier with cargo hold without hopper tank, it is considered that the
thickness of inner hull may be increased by this rule change. However, as there is no CSR
ships with such design, the scantling impact cannot be compared that before and after the
proposed Rule change.

PAGE 81 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-4

PAGE 82 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSCOMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-5

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-5(Direct Strength Analysis)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 83 OF 171

RULE CHANGE NOTICE NO.1-5

COMMON STRUCTURAL RULES FOR BULK CARIIERS

For technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-5.

CHAPTER 7 DIRECT STRENGTH ANALYSIS
Section 2 GLOBAL STRENGTH FE ANALYSIS OF CARGOHOLD STRUCTURES

2. Analysis model
2.2 Finite element modeling
2.2.4
When orthotropic elements are not used in FE model:•mesh size is to be equal to or less than the representative spacing of longitudinal stiffeners or transverse side
frames•stiffeners are to be modeled by using rod and/or beam/bar elements•

where a double hull is fitted, webs of primary supporting members are to be divided by at least threeelements height-wise. However, for transverse primary supporting members inside hopper tank and top sidetank, which are less in height than the space between ordinary longitudinal stiffeners, two elements on theheight of primary supporting members are accepted.

•

where no double hull construction is fitted, side shell frames and their end brackets are to be modeled byusing shell elements for web and shell/beam/rod elements for face plate. Webs of side shell frames need not
be divided along the direction of depth•

aspect ratio of elements is not to exceed 1:4.

An example of typical mesh is given in App 1.

2.3 Boundary conditions
2.3.1
Both ends of the model are to be simply supported according to Tab 1 and Tab 2. The nodes on the longitudinal

members at both end sections are to be rigidly linked to independent points at the neutral axis on the centreline
as shown in Tab 1. The independent points of both ends are to be fixed as shown in Tab 2.
Table 1: Rigid-link of both ends
Translational
Dx
Dy
Dz
Rx
All longitudinal members
RL
RL
RL
RL means rigidly linked to the relevant degrees of freedom of the independent point
Nodes on longitudinal members
at both ends of the model

PAGE 84 OF 171

Rotational
Ry
-

Rz
-

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-5

Table 2: Support condition of the independent point
Location of the independent point

Dx
Fix

Independent point on aft end of model
Independent point on fore end of modelTranslational
Dy
Dz
Fix
Fix
Fix
Fix

Rx
- Fix
Fix

Rotational
Ry
-

Rz
-

3. Analysis criteria
3.2 Yielding strength assessment
3.2.1 Reference stresses
Reference stress is Von Mises equivalent stress at the centre of a plane element (shell or membrane) or axial

stress of a line element (bar, beam or rod) obtained by FE analysis through considering hull girder loads
according to [2.5.4] or [2.5.5].
Where the effects of openings are not considered in the FE model, the reference stresses in way of the openings
are to be properly modified with adjusting shear stresses in proportion to the ratio of web height and opening
height.
Where elements under assessment are smaller than the standard mesh size specified in [2.2.4] or [2.2.5], thereference stress may be obtained from the averaged stress over the elements within the standard mesh size.

3.4 Deflection of primary supporting members
The relative deflection, δmax in mm, in the outer bottom plate obtained by FEA is not to exceed the following
criteria:
The maximum relative deflection between the double bottom and the forward (or afterward) transverse bulkhead
obtained from the FE analysis is not to exceed the following criteria:

δ max ≤

li
150

where:

δ max: Maximum relative deflection, in mm, obtained by the following formula, and not including secondary
deflection between the double bottom and the forward (or afterward) transverse bulkhead, in mmδ max = max( δ B1 , δ B 2 )where, δB1 and δB2 are shown in Fig 3.
li: Length or breadth of the flat part of the double bottom, in mm, whichever is the shorter.

PAGE 85 OF 171

RULE CHANGE NOTICE NO.1-5

COMMON STRUCTURAL RULES FOR BULK CARIIERS

li

δB1
δB2

li

δB1

δB2
Figure 3: Definition of relative deflection

PAGE 86 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-5

Section 3 DETAILED STRESS ASSESSMENT

1. General
1.1 Application
1.1.1
This Section describes the procedure for the detailed stress assessment with refined meshes to evaluate highly

stressed areas of primary supporting members.
Where the global cargo hold analysis of Sec 2 is carried out using a model complying with the modelling criteria
of Sec 2, [2.2.4], the areas listed in Tab 1 are to be refined at the locations whose calculated stresses exceed 95%
for non-orthotropic elements or 85 % for orthotropic element but do not exceed 100% of the allowable stress as
specified in Sec 2, [3.2.3].

PAGE 87 OF 171

RULE CHANGE NOTICE NO.1-5

COMMON STRUCTURAL RULES FOR BULK CARIIERS

PAGE 88 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-5(Direct Strength Analysis)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and inthat case any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 89 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for the Changes Regarding the DirectStrength Analysis:
1. Reason for the Rule Change:
1.1 Ch 7, Sec 2, [2.2.4] and [3.2.1]
In a transverse ring in bilge hopper tank, there are some cases where the web height issmaller than the space between ordinary stiffeners. Where the web is divided by threeelements, the element size is relative small. In addition, the element sometimes becomes
smaller so that the aspect ratio of element does not exceed 1:4. It is not considered that suchsmaller elements are appropriate for applying the global strength analysis of cargo holdstructures.
Therefore this rule change is made to clarify the requirements according to theinterpretation in KC ID 149.
1.2 Ch 7, Sec 2, Table 2
The boundary condition in FEA, which restricts rotation along x-axis at fore end of FE
model but allow free rotation at aft end, specified in Table 2. However, this boundary
condition may cause unexpected warping deformation under beam sea condition because theone end of FE model is rotated about x-axis.
It has been noticed that the stress level induced by the warping deformation is sometimes
unreasonable severe, especially, in case of smaller bulk carrier as handy size and Panamax
BCs.
This rule change is an interim solution made to avoid the unexpected rotation in FEA due
to this boundary condition. (Refer to KC ID 340).
A definitive agreement on boundary conditions has later to be made through further
studies that will use same basis in order to make effective comparisons and impact
evaluations.
1.3 Ch 7, Sec 2, [3.2.1]
Stress level of all elements in FE model should be within the allowable criteria specified
in the Rules, in principle. However, the elements having relative small size are often used in
FEA. In this case, the averaged stresses among these elements are normally used where
deemed reasonable by the Society.
This change is made to clarify the requirements for such a case.(Refer to KC ID 340)
1.4 Ch 7, Sec 2, [3.4]The maximum relative deflection is not clear in the current text.
In order to clarify the relative deflection, which does not include the deflection ofordinary stiffeners, the editorial correction is made and new figure which gives a definition of
the deflection of the outer bottom plate is added.
1.5 Ch 7, Sec 3, [1.1.1]
This rule change is made to clarify the requirement for the application of the detailed
stress assessment. (Refer to KC ID 341)

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5

2. Summary of Rule Change
2.1 Ch 7, Sec 2, [2.2.4]
Considering the actual design for the transverses in bilge hopper or topside tank, theheight of transverse web is smaller than the spacing between longitudinals. In order to avoid
the smaller mesh size in such structural members as far as practicable, the rule change is somade that two shell elements can be accepted.
2.2 Ch 7, Sec 2, [2.3.1] Table 2
As an interim solution the rotational boundary condition RX of independent point on at
end of model is changed to “Fix” from “-“.
2.3 Ch 7, Sec 2, [3.2.1] Reference stresses
Where the cargo hold FE model includes the smaller mesh size than the standard meshsize specified in the Rules, the reference stress can be obtained from the averaged stress overthe elements within the standard mesh size.
2.4 Ch 7, Sec 2 [3.4] Deflection of primary supporting members
In order to clarify the definition of the relative deflection of outer bottom structure, thefigure is added in the text and the relevant texts are modified.
2.5 Ch 7, Sec 3, [1.1]
Where the stresses calculated according to the global strength analysis of cargo holdstructures specified in Ch 7 Sec 2 exceed 95% for non-orthotropic elements or 85% fororthotropic elements but not exceed allowable stress, detailed stress analysis specified in Sec
3 is required.

3. Impact on Scantling
3.1 Impact on scantling due to the change in Ch 7, Sec 2, [2.2.4], [3.2.1], [3.4] and Sec 3,[1.1]
As these rule changes specified in 2.1, 2.3, 2.4 and 2.5 above are made for the
clarification, there is no scantling impact due to these changes.
3.2 Impact on scantling due to the changes in Ch 7, Sec 2, Table 2 regarding thecorrection of the boundary conditions
The cargo hold FEA using the boundary condition specified in the current text gives too
unreasonable stress in cross deck.
Due to the unreasonable stresses, the required thickness for cross deck may be than thatfor upper deck plating.
For example, the required thickness for cross deck is 22.5mm (AH32) and 15mm (AH32)
for upper deck according to KC ID 343.
From the engineering point of view, this result caused by the boundary condition which
gives unrealistic warping effect in FE model obviously.
Therefore, the scantling impact due to this change is not carried out.
However, the unreasonable and excessive stresses around the hatch opening and in crossdeck are improved drastically by this modification.
The details of the effect due to the modification of the boundary condition are mentioned in
Annex 1.

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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Annex 1: Details of the effect due to the modification of theboundary conditions
1. FE Analysis and results
In order t to examine the effect due to the modification of the boundary condition regarding
the rotational restriction Rx along x-axe, the FE analysis for one Handy max buck carrier iscarried out as a typical example.
Applied boundary condition is given in Table 1-1.

(1) Case-1

Table 1-1 Applied boundary condition
Boundary condition as per CSR

Independent Point

Dx
Fix

Aft End of Model
Fore End of Model(2) Case-2

Translational
Dy
Fx
Fix

Dz
Fix
Fix

Rx
Fix

Rotational
Ry
-

Rz
-

Rx
Fix
Fix

Rotational
Ry
-

Rz
-

Modified boundary condition

Independent Point

Dx
Fix

Aft End of Model
Fore End of Model

Translational
Dy
Fx
Fix

Dz
Fix
Fix

Applied loading condition and load case are full load homogeneous condition and EDW “P1”.
As the effect due to the boundary condition is mainly appeared in the stresses of structures
around the hatch opening and cross deck under beam sea condition, the calculated stresses incross deck and deformations for full load condition under beam sea (P1) as a typical example.
The sampling point of the stress of cross deck is shown in Fig. 1-1.
P

C.L

6

4

1

9

12

14

7

5

2

10

13

15

3

11

8

S

Fig. 1-1 Sampling Point

PAGE 92 OF 171

16

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5

The stresses of the sampling points for case 1 and case 2 are shown in Table 1-2. The stresslevel in cross deck is given in Figure 1-2 and the deformation of the FE model is given in Fig.
1-3.
Table 1-2 Stresses at the sampling points in Cross Deck in full load condition under beam sea (P1)

ID
1
2
3
4
5
6
7
8

σallowable(N/mm2)
326
235
235
326
235
326
235
235

σe (N/mm2)
Case-1Case-2(CSR)(Modified)
41
229
103
145
165
137
145
109
195
168
246
94
167
112
144
153

ID
9
10
11
12
13
14
15
16

σallowable(N/mm2)
326
235
235
326
235
326
235
235

PAGE 93 OF 171

σe (N/mm2)
Case-1Case-2(CSR)(Modified)
439
224
213
141
153
134
201
132
249
174
108
68
103
91
205
150

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5

COMMON STRUCTURAL RULES FOR BULK CARRIERSNG(1) Case -1(1) Case 1

Fig-5 Deformation (Case-2 / Boundary Condition of CSR)

(2) Case 2

Fig. 1-2 Stress level in the cross deck in full load condition under beam sea (P1)

PAGE 94 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5(1) Case 1(2) Case 2
Fig. 1-3 Deformation for FE model at the full load condition under beam sea (P1)

PAGE 95 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-5

COMMON STRUCTURAL RULES FOR BULK CARRIERS

2. Conclusion
According to Fig 1-3(1), the deformation of FE model is warped unreasonably due to theboundary condition that is the aft end of FE model is free. Hence, the stress distribution incross deck forward the mid hold of FE model is different from that of afterward the mid holdand the stress value in cross deck seems to be excessive as shown in Fig 1-2(1) and Table 1-1.
On the other hand, the deformation of FE model for case 2 is not observed the unreasonablewarp because the rotational restriction of both ends of FE model is applied, as shown in Fig 13(2). Hence, the stress distribution in forward cross deck forward the mid hold of FE model issimilar to that afterward the mid hold and excessive stress values are not appeared in crossdeck as shown in Fig. 1-2(2) and Table 1-1.

Then, it is concluded that
(1) The boundary in current text gives excessive and unreasonable results.
(2) The corrected boundary condition does not give excessive and unreasonable results.
In order to evaluate the FEA results properly, the incorrect boundary condition should be
revised to avoid the unreasonable warping deformation in FE model.

PAGE 96 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-6

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-6(Fatigue Check for Longitudinals)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 97 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-6.

CHAPTER 4 DESIGN LOADS
Section 5 EXTERNAL PRESSURES

2. External pressures on exposed decks
2.1 General
2.1.1
The external pressures on exposed decks are to be applied for the local scantling check of the structures on

exposed deck but not applied for fatigue strength assessment.
If a breakwater is fitted on the exposed deck, no reduction in the external pressures defined in [2.2] and [2.3] isallowed for the area of the exposed deck located aft of the breakwater.

PAGE 98 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-6

Section 6 INTERNAL PRESSURES AND FORCES

2. Lateral pressure due to liquid
2.1 Pressure due to liquid in still water
2.1.3
For fatigue strength assessment, the liquid pressure in still water pBS, in kN/m2, is given by the following formula.

pBS = ρ L g ( zTOP − z )If the pBS is negative, pBS is to be taken equal to 0.
Where the considered load point is located in the fuel oil, other oils or fresh water tanks, liquids are assumed to
be fulfilled up to the half height of the tanks and zTOP is taken to the Z coordinate of the liquid surface at the
upright condition

PAGE 99 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERSCHAPTER 8 FATIGUE CHECK OF STRUCTURALDETAILS
Section 1 GENERAL CONSIDERATION

1. General
1.3 Subject members
1.3.1
Fatigue strength is to be assessed, in cargo hold area, for members described in Tab 1, at the consideredlocations.
Table 1: Members and locations subjected to fatigue strength assessment
Members

Inner bottom plating
Inner side plating
Transverse bulkhead
Hold frames of single side bulk carriers
Ordinary stiffeners in double side space
Ordinary stiffeners in upper and lower
wing tankOrdinary stiffeners in double bottom
Hatch corners

Details

Connection with sloping and /or vertical plate of lower stool
Connection with sloping plate of hopper tankConnection with sloping plate of hopper tankConnection with sloping plate of lower stool
Connection with sloping plate of upper stool
Connection to the upper and lower wing tankConnection of longitudinal stiffeners with web frames andtransverse bulkhead
Connection of transverse stiffeners with stringer or similar
Connection of longitudinal stiffeners with web frames andtransverse bulkhead
Connection of longitudinal stiffeners with floors and floors in wayof lower stool or transverse bulkheadFree edges of hatch corners

3. Loading
3.1 Loading condition
3.1.1
The loading conditions to be considered are defined in Tab 2 depending on the ship type. The standard loading

conditions illustrated in Ch 4, App 3 are to be considered.

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COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 2:
Ship type
BC-A
BC-B
BC-C

RULE CHANGE NOTICE NO.1-6

Loading conditions

Full load condition
Homogeneous
Alternate

9
9
9

9
-----

PAGE 101 OF 171

Ballast condition
Normal ballast
Heavy ballast

9
9
9

9
9
9

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Section 4 STRESS ASSESSMENT OF STIFFENERS

1. General
1.1 Application
1.1.1
Hot spot stress ranges and structural hot spot mean stresses of longitudinal stiffeners are to be assessed in linewith the requirements of this Section.
1.1.2
The hot spot stress ranges and structural hot spot mean stresses of longitudinal stiffeners are to be evaluated at

the face plate of the longitudinal considering the type of longitudinal end connection and the following locations.
(1) Transverse webs or floors other than those at transverse bulkhead of cargo hold or in way of stools, such that
additional hot spot stress due to the relative displacement may not be considered. These longitudinal end
connections are defined in Tab 1. When transverse webs or floors are watertight, the coefficients Kgl and Kgh
as defined in Tab 2 are to be considered instead of those defined in Tab 1(2) Transverse webs or floors at transverse bulkhead of cargo hold in way of stools, such that additional hot spot
stress due to the relative displacement should be considered. These longitudinal end connections are definedin Tab 2. When transverse webs or floors at transverse bulkhead of cargo hold or in way of stools are notwatertight, the coefficients Kgl and Kgh as defined in Tab 1 are to be considered instead of those defined in
Tab 2.

2. Hot spot stress range
2.3 Stress range according to the simplified procedure
2.3.1 Hot spot stress ranges
The hot spot stress range, in N/mm2, due to dynamic loads in load case “i” of loading condition “(k)” is to beobtained from the following formula:() (Δσ W , i ( k ) = σ GW , i1( k ) + σ W 1, i1( k ) − σ W 2, i1( k ) + σ d , i1( k ) − σ GW , i 2( k ) + σ W 1, i 2( k ) − σ W 2, i 2( k ) + σ d , i 2( k )

)

where

σGW , i1(k), σGW , i2(k) : Stress due to hull girder moment, defined in [2.3.2]
σW1 , i1(k), σW1 , i2(k) : Stress σLW ,i j(k) , σCW ,i j (k) and σLCW , i j (k) due to hydrodynamic or inertial pressure when thepressure is applied on the same side as the ordinary stiffener depending on the considered
case

σW2 , i1(k), σW2 , i2(k) : Stress σLW , i j(k) , σCW , i j (k) and σLCW , i j (k) due to hydrodynamic or inertial pressure when thepressure is applied on the side opposite to the stiffener depending on the considered case

σLW , i1(k), σLW , i2(k) : Stresses due to wave pressure, defined in [2.3.3]
σCW , i1(k), σCW , i2(k) : Stresses due to liquid pressure, defined in [2.3.4]
σLCW , i1(k), σLCW , i2(k) : Stresses due to dry bulk cargo pressure, defined in [2.3.5]
PAGE 102 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERS

σd , i1(k), σd , i2(k)RULE CHANGE NOTICE NO.1-6: Stress due to relative displacement of transverse bulkhead or floor in way of stools,
defined in [2.3.6].

2.3.2 Stress due to hull girder moments
The hull girder hot spot stress, in N/mm2, in load case “i1” and “i2” for loading condition “(k)” is to be obtained

from the following formula:σ GW , i j ( k ) = K gh ⋅ (CWV , i j σ WV , i j − CWH , i j σ WH , ( k ) )( j = 1, 2)

where:
Kgh: Geometrical stress concentration factor for nominal hull girder stress depending on the detail of end
connection as defined in Tab 1. Kgh is given in Tab 1 and Tab 2 for the longitudinal end connection
specified in [1.1.2](1) and [1.1.2](2), respectively.
The stress concentration factor can be evaluated directly by the FE analysis.

CWV , i1 , CWV , i2 , CWH , i1 , CWH , i2

σWV , i1 , σWV , i2 , σWH , (k): Load combination factors for each load case defined in Ch 4, Sec 4, [2.2]: Nominal hull girder stresses, in N/mm2, defined in Sec 3, [2.2.2]

2.3.3 Stress due to wave pressure
The hot spot stress, in N/mm2, due to the wave pressure in load case “i1” and “i2” for loading condition “(k)” isto be obtained from the following formula:⎛ 6x f 6x f 2 ⎞K gl K s C NE , i j ( k ) pW , i j ( k ) sl 2 ⎜1 −
+ 2 ⎟
⎜
l
l ⎟⎠ 3⎝
σ LW , i j ( k ) =1012w⎛ 6x f 6x f 2 ⎞K gl K s pCW , i j ( k ) sl ⎜1 −
+ 2 ⎟
⎜
l
l ⎟⎠ 3⎝
σ LW , i j ( k ) =1012 w( j = 1, 2)

2( j = 1, 2)⎧⎪2CNE,i 1( k ) pW ,i 1( k ) ; CNE,i 1( k ) < 0.5
pCW ,i 1( k ) = ⎨; CNE ,i 1( k ) ≥ 0.5⎪⎩ pW ,i 1( k );CNE,i 2( k ) < 0.5⎧⎪0pCW ,i 2( k ) = ⎨;
CNE ,i 2( k ) ≥ 0.5⎪⎩(2CNE,i 2( k ) − 1)pW ,i 2( k )where:
pW , i j(k) : Hydrodynamic pressure, in kN/m2, specified in Ch 4, Sec 5, [1.3], [1.4] and [1.5] , with fp = 0.5, inload case “i1” and “i2” for loading condition “(k)”. When the location of the considered member isabove the waterline, the hydrodynamic pressure is to be taken as the pressure at waterline.
Kgl: Geometrical stress concentration factor for stress due to lateral pressure depending on the detail of end
connection as defined in Tab 1. Kgl is given in Tab. 1 and Tab. 2 for the longitudinal end connection
specified in [1.1.2] (1) and [1.1.2] (2), respectively
The stress concentration factor can be evaluated directly by the FE analysis when the detail of end
connection is not defined in Tab 1.

PAGE 103 OF 171

RULE CHANGE NOTICE NO.1-6
Ks

COMMON STRUCTURAL RULES FOR BULK CARRIERS: Geometrical stress concentration factor due to stiffener geometry⎡ t f (a 2 − b 2 ) ⎤ ⎡b ⎛ wb ⎞ ⎤ − 3⎟ ⎥ 10⎜1 +⎥ ⎢1 −
K s =1 + ⎢2 wb⎢⎣⎥⎦ ⎣⎢ b f ⎜⎝ wa ⎟⎠ ⎦⎥a,b: Eccentricity, in mm, of the face plate as defined in Fig 1. For angle profile, “b” is to be taken as half
the net actual thickness of the web.

tf, bf: thickness and breadth of face plate, in mm, respectively, as defined in Fig 1

wa , wb : Net section modulus in A and B respectively(see Fig.1), in cm3, of the stiffener about the neutral axis
parallel to Z axis without attached plating.
CNE , i j(k) : Correction factor for the non linearity of the wave pressure range in load case “i1” and “i2” of loading
condition “(k)”
2.5 ⎤
⎧ ⎡ ⎛
pW , i j ( k ), WL ⎞⎟ ⎥⎪ ⎢ ⎜⎪ ⎢ ⎜ z − TLC ( k ) +⎟ ⎥ρg⎪exp ⎢− ⎜⎟ ⎥ for⎪ ⎢ ⎜ pW , i j ( k ), WL⎟ ⎥−1
C NE , i j ( k ) = ⎨ ⎢ ⎜(− ln 0.5) 2.5 ⎟⎟ ⎥
⎜
ρg
⎪ ⎢ ⎝
⎠ ⎥⎦
⎪ ⎣
⎪
for
⎪ 1.0
⎩

TLC(k)

z > TLC ( k ) −z ≤ TLC ( k ) −pW , i j ( k ), WL

ρgpW , i j ( k ), WL

ρg: Draught, in m, of the considered loading condition “(k)”pW , i j(k) , WL : Hydrodynamic pressure, in kN/m2, at water line in load case “i1” and “i2” of loading condition “(k)”z: Z co-ordinate, in m, of the point considereds: Stiffener spacing, in ml

: Span, in m, to be measured as shown in Fig 2. The ends of the span are to be taken at points where thedepth of the end bracket, measured from the face plate of the stiffener is equal to half the depth of thestiffener.

xf: Distance, in m, to the hot spot from the closest end of the span l (see Fig 2)

w: Net section modulus, in cm3, of the considered stiffener. The section modulus w is to be calculated
considering an effective breadth se, in m, of attached plating obtained from the following formulae:()⎧⎡ π ⎛ l 1 − 1 / 3 ⎞⎤⎟⎥ for
⎪0.67 s ⋅ sin ⎢ ⎜
⎜
⎟⎥
⎪
s
6
2
⎢
⎝
⎠⎦
⎣
se = ⎨⎪0.67 s
for
⎪
⎩

6
l
≤
s 1 − 1/ 36l>s 1 − 1/ 3

PAGE 104 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-6

Z
bf
tf

b

a

B

A
tw

hw
tp
X

O

bp
Figure 1: Sectional parameters of a stiffenerlllTrans.

Trans.
hot spot
d/2

d/2
d

xf

l

Figure 2: Span and hot spot of longitudinal stiffeners

PAGE 105 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

2.3.4 Stress due to liquid pressure
The hot spot stress, in N/mm2, due to the liquid pressure in load case “i1” and “i2” for loading condition “(k)” isto be obtained from the following formula:⎛ 6x f 6x f 2 ⎞K gl K s C NI , i j ( k ) p BW , i j ( k ) sl 2 ⎜1 −
+ 2 ⎟
⎜
l
l ⎟⎠
⎝
σ CW , i j ( k ) =
⋅10 3
12 w

( j = 1, 2)

where:
pBW , i j(k) : Inertial pressure, in kN/m2, due to liquid specified in Ch 4, Sec 6, [2.2], with fp = 0.5, in load case “i1”and “i2” for loading condition “(k)”. Where the considered location is located in fuel oil, other oil or
fresh water tanks, no inertial pressure is considered for the tank top longitudinals and when thelocation of the considered member is above the liquid surface in static and upright condition, theinertial pressure is to be taken at the liquid surface line.
CNI , i j(k) : Correction factor for the non linearity of the inertial pressure range due to liquid in load case “i1” and“i2” for loading condition “(k)”
2.5 ⎤
⎧ ⎡ ⎛
p BW , i j ( k ), SF ⎞⎟ ⎥⎪ ⎢ ⎜⎪ ⎢ ⎜ z − z SF +⎟ ⎥ρg⎪exp ⎢− ⎜⎟ ⎥ for⎟ ⎥⎪⎪ ⎢ ⎜ p BW , i j ( k ), SF−
1
C NI , i j ( k ) = ⎨ ⎢ ⎜
2.5 ⎟
(
)
ln
0
.
5
−
⎟ ⎥⎥
ρg
⎪ ⎢ ⎜⎝
⎠ ⎦
⎪ ⎣
⎪
for
⎪ 1.0
⎩⎪

zSF

z > z SF −z ≤ z SF −p BW , i j ( k ), SF

ρgp BW , i j ( k ), SFρg: Z co-ordinate, in m, of the liquid surface. In general, it is taken equal to “ztop” defined in Ch 4 Sec 6.
If the considered location is located in fuel oil, other oil or fresh water tanks, it may be taken as the
distance to the half height of the tank. In general, it is taken as the distance to the top of the tank. In
case of fuel oil tank, it may be taken as the distance to the half height of the tankz

: Z co-ordinate, in m, of the point consideredpBW , i j(k) , SF : Inertial pressure due to liquid, in kN/m2, taken at the liquid surface in load case “i1” and “i2” forloading condition “(k)”. In calculating the inertial pressure according to Ch 4 Sec 6, [2.2.1], x and ycoordinates of the reference point are to be taken as liquid surface instead of tank top.
Kgl, Ks : the stress concentration factor defined in [2.3.3]
2.3.6 Stress due to relative displacement of transverse bulkhead or floor in way of transverse
bulkhead or stool
For longitudinal end connection specified in [1.1.2] (2), tThe additional hot spot stress, in N/mm2, due to therelative displacement in the transverse direction perpendicular to the attached plate between the transverse
bulkhead or floor in way of stools and the adjacent transverse web or floor in load case “i1” and “i2” for loading
condition “(k)” is to be obtained from the following formula.
⎧ K dF − aσ dF − a , i j ( k ) + K dA− a σ dA− a , i j ( k )⎩ K dF − f σ dF − f , i j ( k ) + K dA− f σ dA− f , i j ( k )σ d , i j (k ) = ⎨for point " a"for point " f "( j = 1, 2)

where:
a,f: Suffix which denotes the location considered as indicated in Tab 12.

PAGE 106 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERS
A,F

RULE CHANGE NOTICE NO.1-6: Suffix which denotes the direction, forward (F) and afterward (A), of the transverse web or floor
where the relative displacement is occurred as indicated in Tab 12.(see Fig 3)

σdF-a , i j(k) , σdA-a , i j(k) , σdF-f , i j(k) , σdA-f , i j(k): Additional stress at point “a” and “f ”, in N/mm2, due to therelative displacement between the transverse bulkhead or floors in way of stools and the forward (F)and afterward (A) transverse web or floor respectively in load case “i1” and “i2” for loading condition“(k)”

σ dF −a , i j ( k ) =⎞⎛⎜1 − 1.15 x fA ⎟10 −5lA ⎟w A l F (l A I F + l F I A ) ⎜⎠⎝3.9δ F , i j ( k ) EI A I F⎡ 3.9δ
A, i j ( k ) EI A I F⎤⎞⎛⎜1 − 1.15 x fA ⎟ − 0.9δ A, i j ( k ) EI A x fA ⎥ 10 −5⎢ w A l A (l A I F + l F I A ) ⎜⎥lA ⎟wAl A3⎠⎝⎣⎦σ dA−a , i j ( k ) = ⎢⎤⎛⎞⎜1 − 1.15 x fF ⎟ − 0.9δ F , i j ( k ) EI F x fF ⎥ 10 −5⎥⎢ w F l F (l A I F + l F I A ) ⎜lF ⎟wF l F 3⎝⎠⎦⎣⎡ 3.9δ
F , i j ( k ) EI A I F

σ dF − f , i j ( k ) = ⎢σ dA− f , i j ( k ) =δF , i j(k) , δA , i j(k)⎛⎞⎜1 − 1.15 x fF ⎟ 10 −5
wF l A (l A I F + l F I A ) ⎜lF ⎟⎝⎠3.9δ A, i j ( k ) EI A I F: Relative displacement, in mm, in the transverse direction perpendicular to the attached plate

between the transverse bulkhead or floor in way of stools and the forward (F) and afterward (A)transverse web or floor in load case “i1” and “i2” for loading condition “(k)” (see Fig 3)(a) For longitudinals penetrating floors in way of stools
Relative displacement is defined as the displacement of the longitudinal in relation to the line
passing through the stiffener end connection at the base of the stool measured at the first floor
forward (F) or afterward (A) of the stool.
(b) For longitudinals other than (a)Relative displacement is defined as the displacement of the longitudinal in relation to its original
position measured at the first forward (F) or afterward (A) of the transverse bulkhead.
Where the stress of the face of longitudinal at the assessment point due to relative displacement is
tension, the sign of the relative displacement is positive.
IF , IA: Net moment of inertia, in cm4, of forward (F) and afterward (A) longitudinal

KdF-a , KdA-a , KdF-f , KdA-f : Stress concentration factor for stiffener end connection at point “a” and “f “ subject
to relative displacement between the transverse bulkhead and the forward (F) and afterward (A)transverse web or floors in way of stool respectively as defined in Tab 12. The stress concentration
can be evaluated directly by the FE analysis when the detail of end connection is not defined in Tab
12.
lF , lA : Span, in m, of forward (F) and afterward (A) longitudinal to be measured as shown in Fig 2

xfF , xfA : Distance, in m, to the hot spot from the closest end of lF and lA respectively (see Fig 2).

PAGE 107 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS
Aft

Fore

A

a

Trans.

F

f

T.BHD

Trans.

Aft

Fore
IA

δA

IF

a

lA
Trans.

δF

f

T. BHDlF
Trans.

Figure 3 Relative displacement between the transverse bulkhead and the transverse web or
floor Definition of the relative displacement (Example of the side longitudinal)

3. Hot Spot Mean Stress
3.3 Mean stress according to the simplified procedure
3.3.1 Hot spot mean stresses
The structural hot spot mean stress, in N/mm2, in loading condition “(k)” regardless of load case “i” is to beobtained from the following formula:σ mean, ( k ) = σ GS , ( k ) + σ S1, ( k ) − σ S 2, ( k ) + σ dS , ( k )whereσGS , (k) : Stress due to still water hull girder moment, defined in [3.3.2]
σS1 , (k) : Stress due to static pressure when the pressure is applied on the same side as the ordinary stiffener
depending on the considered case, with consideration of the stresses defined in [3.3.3] to [3.3.5]

σS2 , (k) : Stress due to static pressure when the pressure is applied on the side opposite to the stiffener
depending on the considered case, with consideration of the stresses defined in [3.3.3] to [3.3.5]

σLS , (k) : Stress due to hydrostatic pressure, defined in [3.3.3]
σCS , (k) : Stress due to liquid pressure in still water, defined in [3.3.4]
σLCS , (k) : Stress due to dry bulk cargo pressure in still water, defined in [3.3.5]
σdS , (k) : Stress due to relative displacement of transverse bulkhead in still water, defined in [3.3.6].

PAGE 108 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-6

3.3.2 Stress due to still water hull girder moment
The hot spot stress due to still water bending moment, in N/mm2, in loading condition “(k)” is to be obtainedwith the following formula:σ GS , ( k ) = K gh

M S , ( k ) (z − N )
IY

10 −3

where:MS , (k): Still water vertical bending moment, in kN.m, defined in Sec 3, [3.2.2].

3.3.3 Stress due to hydrostatic and hydrodynamic pressure
The hot spot stress due to hydrostatic and hydrodynamic pressure, in N/mm2, in loading condition “(k)” is to beobtained with the following formula:⎛ 6x f 6x f 2 ⎞+ 2 ⎟K gl K s p S , ( k ) sl 2 ⎜1 −
⎜
l
l ⎟⎠
⎝
σ LS , ( k ) =
10 3
12 w
2
pCW , i 1( k ) + pCW , i 2 ( k ) ⎫ 2 ⎛ 6 x f 6 x f ⎞⎧⎜K gl K s ⎨ p S , ( k ) ++ 2 ⎟⎬ sl ⎜ 1 −
2
l
l ⎟⎠
⎩
⎭ ⎝
⋅ 10 3σ LS , ( k ) =12 w

where:
pS , (k): Hydrostatic pressure, in kN/m2, in loading condition “(k)” specified in Ch 4, Sec 5, [1.2].

pCW , i j(k): Corrected hydrodynamic pressure, in kN/m2, according to [2.3.3], with fp = 0.5, in load case “i1” and“i2” for loading condition “(k)”i: Suffix which denotes the load case specified in Sec 2 [2.1.1], when calculating the mean stress, "I" isto be used.

3.3.4 Stress due to liquid pressure in still water
The structural hot spot mean stress due to liquid pressure, in N/mm2, in loading condition “(k)” is to be obtainedwith the following formula:⎛
6xf
6 x f 2 ⎞⎟+K gl K s pCS, ( k )sl 2 ⎜1 −⎜ll 2 ⎟⎠⎝σ CS, ( k ) =
10 3
12w

where:
pCS ,(k) : Liquid pressure in still water, in kN/m2, in loading condition “(k)” specified in Ch 4, Sec 6, [2.1].
Where the considered location is located in fuel oil, other oil or fresh water tanks, dAP and PPV definedin Ch 4 Sec 6 are to be taken equal to 0 and zTOP specified in Ch 4 Sec 6, [2.1] is to be taken equal tozSF specified in [2.3.4].

PAGE 109 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 1: Stress concentration factors for the stiffener end connection
Structural type

Assessedpoint

1

Collarplate

Bracket size

watertightStress concentration factors
Kgl

Kgh

KdF

KdA

-----

1.5

1.1

1.15

1.5

nonwatertight

-----

1.65

1.1

-----

-----

watertight

-----

1.1

1.05

1.55

1.05

dw ≤ d<1.5dw

1.45

1.1

1.15

1.4

1.5dw ≤ d

1.4

1.05

1.15

1.35

dw ≤ d<1.5dw

1.55

1.1

-----

-----

1.5dw ≤ d

1.5

1.05

-----

-----

dw ≤ d<1.5dw

1.1

1.05

1.15

1.1

1.5dw ≤ d

1.05

1.05

1.1

1.05

dw ≤ d<1.5dw

1.4

1.1

1.1

1.35

1.5dw ≤ d

1.35

1.05

1.05

1.3

dw ≤ d<1.5dw

1.5

1.1

-----

-----

1.5dw ≤ d

1.45

1.05

-----

-----

dw ≤ d<1.5dw

1.05

1.05

1.1

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

dw ≤ d<1.5dw

1.1

1.05

1.05

1.25

1.5dw ≤ d

1.05

1.05

1.05

1.2

dw ≤ d<1.5dw

1.3

1.1

1.35

1.05

1.5dw ≤ d

1.3

1.05

1.3

1.05

dw ≤ d<1.5dw

1.4

1.1

-----

-----

1.5dw ≤ d

1.4

1.05

-----

-----

dw ≤ d<1.5dw

1.1

1.05

1.05

1.2

1.5dw ≤ d

1.05

1.05

1.05

1.15

dw ≤ d<1.5dw

1.3

1.1

1.55

1.1

1.5dw ≤ d

1.3

1.05

1.5

1.05

dw ≤ d<1.5dw

1.35

1.1

-----

-----

1.5dw ≤ d

1.35

1.05

-----

-----

A

F
2

watertightA
nonwatertightF

3

watertightwatertightanonwatertight4fwatertightawatertightwatertightfnonwatertight5awatertightwatertightfnonwatertight

PAGE 110 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-6

Table 1: Stress concentration factors for the stiffener end connection (continued)
Structural type

Assessedpoint

6

Collarplate

watertightanonwatertightf

7

watertightwatertightanonwatertightf
8

watertightwatertightanonwatertight

Bracket size

Stress concentration factors
Kgl

Kgh

KdF

KdA

dw ≤ d<1.5dw

1.1

1.05

1.05

1.1

1.5dw ≤ d

1.05

1.05

1.05

1.05

dw ≤ d<1.5dw

1.15

1.05

-----

-----

1.5dw ≤ d

1.1

1.05

-----

-----

dw ≤ d<1.5dw

1.05

1.05

1.1

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

dw ≤ d<1.5dw

1.1

1.05

1.05

1.2

1.5dw ≤ d

1.05

1.05

1.05

1.15

dw ≤ d<1.5dw

1.15

1.05

-----

-----

1.5dw ≤ d

1.1

1.05

-----

-----

dw ≤ d<1.5dw

1.05

1.05

1.05

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

dw ≤ d<1.5dw

1.1

1.1

1.05

1.15

1.5dw ≤ d

1.05

1.05

1.05

1.1

dw ≤ d<1.5dw

1.1

1.1

-----

-----

1.5dw ≤ d

1.05

1.05

-----

-----

dw ≤ d<1.5dw

1.05

1.05

1.1

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

f

watertightawatertight

-----

1.4

1.05

1.05

1.75

f

watertight

-----

1.6

1.05

1.7

1.05

a

watertight

-----

1.3

1.05

1.05

1.75

f

watertight

-----

1.55

1.05

1.3

1.05

9

10

PAGE 111 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 1: Stress concentration factors for the stiffener end connection (continued)
Structural type

Assessedpoint

Collarplate

Bracket sizeawatertightfStress concentration factors
Kgl

Kgh

KdF

KdA

-----

1.1

1.05

1.05

1.2

watertight

-----

1.75

1.05

1.4

1.05

a

watertight

-----

1.1

1.05

1.05

1.2

f

watertight

-----

1.3

1.05

1.05

1.05

a

watertight

-----

1.05

1.05

1.05

1.15

f

watertight

-----

1.95

1.05

1.55

1.05

a

watertight

-----

1.05

1.05

1.05

1.15

f

watertight

-----

1.7

1.05

1.15

1.05

11

12

13

14

PAGE 112 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-6

Table 1: Stress concentration factors for non-watertight longitudinal end connection attransverse webs or floors other than transverse bulkheads or floors in way of stools
Bracket type

Assessedpoint

Bracket size

Stress concentration factors
Kgl
Kgh

1
A

F
a

-----

1.65

1.1

dw ≤ d < 1.5dw

1.55

1.1

1.5dw ≤ d

1.5

1.05

dw ≤ d < 1.5dw

1.5

1.1

1.5dw ≤ d

1.45

1.05

dw ≤ d < 1.5dw

1.4

1.1

1.5dw ≤ d

1.4

1.05

dw ≤ d < 1.5dw

1.35

1.1

1.5dw ≤ d

1.35

1.05

dw ≤ d < 1.5dw

1.15

1.05

1.5dw ≤ d

1.1

1.05

2
A

F
a

3
A

F
a

4
A

F
f

5
A

F
f

6
A

F
a

PAGE 113 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 1: Stress concentration factors for non-watertight longitudinal end connection at transverse
webs or floors other than transverse bulkheads or floors in way of stools (continued)
Assessedpoint

Bracket type

7
A

Bracket size

Stress concentration factors
Kgl
Kghdw ≤ d < 1.5dw

1.15

1.05

1.5dw ≤ d

1.1

1.05

dw ≤ d < 1.5dw

1.1

1.1

1.5dw ≤ d

1.05

1.05

d ≤ 2h1.45

1.1

d ≤ 2.5h

1.35

1.1

1.15

1.1

1.85

1.1

1.15

1.1

1.35

1.1

1.1

1.1

2.05

1.1

1.1

1.1

1.8

1.1

F
a

8
A

F
a

9

Tripping
bracket

10

A

F
a

A

F

Tripping
bracket11

Tripping
bracket

a

A

F

a

f

12
Tripping
bracket

A

F

a

f

13
Tripping
bracketA

F

Tripping
bracketAF

d1 ≤ 2.5handh ≤ d2af

14

d1 ≤ 2handh ≤ d2af

d1 ≤ 2handh ≤ d2d1 ≤ 2.5handh ≤ d2

PAGE 114 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-6

Table 2: Stress concentration factors for watertight longitudinal end connection at transverse
bulkheads and floors in way of stools
Assessedpoint

Bracket type

1
A

F

a

f

2
A

F

a

f

3
A

F

a

f

4
A

F

a

f

5
A

F

a

f

6
A

F

a

f

Bracket size

Stress concentration factors
Kgl
Kgh
KdF
KdA

-----

1.5

1.1

1.15

1.5

-----

1.1

1.05

1.55

1.05

dw ≤ d<1.5dw

1.45

1.1

1.15

1.4

1.5dw ≤ d

1.4

1.05

1.15

1.35

dw ≤ d<1.5dw

1.1

1.05

1.15

1.1

1.5dw ≤ d

1.05

1.05

1.1

1.05

dw ≤ d < 1.5dw

1.4

1.1

1.1

1.35

1.5dw ≤ d

1.35

1.05

1.05

1.3

dw ≤ d<1.5dw

1.05

1.05

1.1

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

dw ≤ d<1.5dw

1.1

1.05

1.05

1.25

1.5dw ≤ d

1.05

1.05

1.05

1.2

dw ≤ d < 1.5dw

1.3

1.1

1.35

1.05

1.5dw ≤d

1.3

1.05

1.3

1.05

dw ≤ d < 1.5dw

1.1

1.05

1.05

1.2

1.5dw ≤ d

1.05

1.05

1.05

1.15

dw ≤ d < 1.5dw

1.3

1.1

1.55

1.1

1.5dw ≤ d

1.3

1.05

1.5

1.05

dw ≤ d < 1.5dw

1.1

1.05

1.05

1.1

1.5dw ≤ d

1.05

1.05

1.05

1.05

dw ≤ d < 1.5dw

1.05

1.05

1.1

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

PAGE 115 OF 171

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 2: Stress concentration factors for watertight longitudinal end connection at transverse
bulkheads and floors in way of stools (continued)
Bracket type7
A

F

Bracket sizeadw ≤ d<1.5dw

1.1

1.05

1.05

1.2

1.5dw ≤ d

1.05

1.05

1.05

1.15

dw ≤ d < 1.5dw

1.05

1.05

1.05

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

dw ≤ d<1.5dw

1.1

1.1

1.05

1.15

1.5dw ≤ d

1.05

1.05

1.05

1.1

dw ≤ d < 1.5dw

1.05

1.05

1.1

1.05

1.5dw ≤ d

1.05

1.05

1.05

1.05

1.4

1.05

1.05

1.75

1.6

1.05

1.7

1.05

1.3

1.05

1.05

1.75

1.55

1.05

1.3

1.05

1.1

1.05

1.05

1.2

1.75

1.05

1.4

1.05

1.1

1.05

1.05

1.2

1.3

1.05

1.05

1.05

1.05

1.05

1.05

1.15

1.95

1.05

1.55

1.05

f

8
A

F

a

f

9
Tripping
bracket

A

F

a

A

F

a

Tripping
bracketf

11

Tripping
bracket

A

F

a

f

12

Tripping
bracket

A

F

a

f

13

Kgl

d ≤ 2hf

10

Stress concentration factors
Kgh
KdF
KdA

Assessedpoint

Tripping A
bracketFafd ≤ 2.5hd1 ≤ 2handh ≤ d2d1 ≤ 2.5handh ≤ d2d1 ≤ 2handh ≤ d2

PAGE 116 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERS

14Tripping
bracket

A

F

a

f

RULE CHANGE NOTICE NO.1-6

d1 ≤ 2.5handh ≤ d2

PAGE 117 OF 171

1.05

1.05

1.05

1.15

1.7

1.05

1.15

1.05

RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERSPAGE 118 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-6(Fatigue Check for Longitudinals)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are, individuallyand collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individually and collectively,
assume no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on theinformation or advice in this document or howsoever provided, unless that person has signed a contract with therelevant IACS Member entity for the provision of this information or advice and in that case any responsibility or
liability is exclusively on the terms and conditions set out in that contract.

PAGE 119 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for the Changes Regarding Fatigue Check forLongitudinals
1. Reason for the Rule Change in:
1.1 Chapter 4, Section 5, [2.1.1]
Since the external pressures on exposed deck are set up in order to check the local scantlingconsidering the effect on green water and are not referenced in the pressures specified in Ch 8 Sec 4,[2.3.3], the clarification is made that these pressures are not necessary to consider for the fatigue
check.
1.2 Chapter 4, Section 6, [2.1.3]
For fatigue strength assessment, the filling height of liquid in the tank is to consider the average
one because the fatigue strength of the structures is dominant to the most frequent condition in the
representative loading condition. Generally, for water ballast tanks, the most frequent condition isassumed that the upper surface of liquid matches to upper level of the tank according to KC ID 359.
1.3 Chapter 8, Section 1, Table 1 and [3.1.1]
These changes are made in order to clarify the requirements.
1.4 Chapter 8, Section 4, [2.3.3] and [3.3.3]
To consider the nonlinear relation between wave pressure and wave height, the correction factorof the pressure range is specified in Ch8 Sec4 [2.3.3] of the current CSR. This correction factor isintroduced to define an equivalent linear long term distribution of stress range which gives a fatigue
damage equivalent to the damage according to the nonlinear distribution of stress range. However,the consideration of this nonlinearity on the evaluation of mean stress was not included.
This consideration is naturally necessary to consider the nonlinear effect of wave pressure on
the fatigue damage of side longitudinals. Consequently, Ch8 Sec4 [2.3.3] is to be modified so that
this consideration can be taken into account. And Ch8 Sec4 [3.3.3] is also to be modified so that themean stress considering the nonlinear effect can be evaluated.
1.5 Chapter 8, Section 4, [2.3.4] and [3.3.4]
The interpretation is added to the text for the case where the considered locations are located infuel oil tank, other oil tank or fresh water tank, according to KC ID 359.
1.6 Chapter 8, Section 4, [2.3.6]
The clarification is made for the relative displacement according to the answer in KC ID 342.
1.7 Chapter 8, Section 4, Table 1
The table gives the stress concentration factors for representative stiffener end connections.
However, some types of stiffener end connection not defined in the table are used for non watertighttransverses and size of bracket was not defined in the table.
The modification of the table is made to clarify the application of the types of stiffener end
connections and the size of bracket based on the investigation result of actual ship design, according
to KC IDs 255, 256, 257, 258 and 259.

2. Summary of Rule Change
2.1 Chapter 4, Section 5, [2.1.1]
The sentence regarding the external pressure on exposed deck is added to the paragraph [2.1.1].

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

2.2 Chapter 4, Section 6, [2.1.3]
The new paragraph [2.1.3] regarding the liquid pressure in still water is added.
2.3 Chapter 8, Section 1, Table 1 and [3.1.1]
The word “floors in way of lower stool” is added to the details for ordinary stiffener in double
bottom in Table 1 and the sentence regarding standard loading condition for fatigue strength
assessment is added to [3.1.1].
2.4 Chapter 8, Section 4, [2.3.3] and [3.3.3]
In order to consider the nonlinearity on the evaluation of mean stress, the formulae are modified asfollows.
(1) [2.3.3]⎛ 6x f 6x f 2 ⎞2⎜
K gl K s C NE , i j ( k ) pW , i j ( k ) sl 1 −
+ 2 ⎟
⎜
l
l ⎟⎠ 3⎝( j = 1, 2)
σ LW , i j ( k ) =1012w⎛ 6x f 6x f 2 ⎞K gl K s pCW , i j ( k ) sl ⎜1 −
+ 2 ⎟
⎜
l
l ⎟⎠ 3⎝
σ LW , i j ( k ) =
10
12w
2

( j = 1, 2)⎧⎪2C NE ,i1( k ) pW ,i1( k ) ; C NE ,i1( k ) < 0.5
pCW ,i1( k ) = ⎨; C NE ,i1( k ) ≥ 0.5⎪⎩ pW ,i1( k )⎧⎪0pCW ,i 2 ( k ) = ⎨⎪⎩(2C NE ,i 2( k ) − 1) pW ,i 2( k ); C NE ,i 2( k ) < 0.5; C NE ,i 2( k ) ≥ 0.5(2) [3.3.3]⎛ 6x f 6x f 2 ⎞K gl K s p S , ( k ) sl 2 ⎜1 −
+ 2 ⎟
⎜
l
l ⎟⎠
⎝
σ LS , ( k ) =
10 3
12 w
2
pCW , i 1( k ) + pCW , i 2( k ) ⎫ 2 ⎛ 6 x f 6 x f ⎞
⎧
⎜
+ 2 ⎟
K gl K s ⎨ p S , ( k ) +⎬ sl ⎜ 1 −
l
2
l ⎟⎠
⎭ ⎝
⎩
σ LS , ( k ) =⋅ 10 312w

In addition, the texts referring to Table 1 and Table 2 are changed according to the modification ofthese tables. The background of these formulae is given in Annex 1.
2.5 Chapter 8, Section 4, [2.3.4] and [3.3.4]
Where the considered locations are located in fuel oil tank, other oil tank or fresh water tank, ZSF
may be taken as the distance to the half height of the tank.
In addition, where the hydrostatic pressure of the considered member located in fuel oil tank,other oil tank or fresh water tank is calculated according to Ch 4 Sec 6 [2.1.1], dAP and PPV definedin Ch 4 Sec 6 are to be taken equal to 0.
2.6 Chapter 8, Section 4, [2.3.6]
The text on the definition of relative displacement is added.

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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

2.7 Chapter 8, Section 4 Table 1
The current Table 1 is divided into two tables. One is for stress concentration factor for nonwatertight longitudinal end connection and the other is for stress concentration factor for watertightlongitudinal connection. In addition, the bracket size is added based on the actual design.

3. Effect due to this change
3.1 Clarification of the rules specified in 2.1, 2.2, 2.4 and 2.5
As these changes are made for clarification, there is no scantling impact due to this clarification.
3.2 Chapter 8, Section 4, [2.3.3] and [3.3.3]
The effect on assessed fatigue damage due to the modification was examined. Sample ships arelisted in Table G1. Fatigue damages of side longitudinal stiffener with as-built scantling according
to the current rule and the modified proposal were assessed and compared in Figs. 1(a) and (b).
Assessed fatigue damages are well improved to agree with the current experiences that the side
longitudinal stiffeners were hardly fatigue damaged.

Table 1: List of Examined Ships
Vessel ID
Type
Lpp (Rule)
B
D
Max.
Homo.
Alt.
d
N.B.
H.B.
NA

D1
D2
D3
Cape Handymax Handymax
275.48178.48178.29
45.00
32.20
31.00
24.30
16.50
16.50
17.80
11.68
11.66
17.80
11.68
11.66
17.80
11.68
11.66
7.59
5.87
6.19
8.67
9.78
7.91
10.56
6.16
6.08

D1

S1
S3
Cape Handymax
275.00182.85
45.00
32.26
24.40
17.80
17.93
12.45
17.93
12.45
17.93
12.45
8.06
5.02
9.14
8.02
7.00
11.31

D2

S7
Cape
286.91
50.00
24.10
17.88
17.88
17.88
7.01
8.92
10.67
D3

25

15

10

C urrent
M odified

V erticalLocation (m )V erticalLocation (m )V erticalLocation (m )

15

15

20

10

C urrent
M odified

5

10

C urrent
M odified

5

5

0

0

0
0.0

0.5

1.0
1.5
Fatigue D am age

2.0

2.5

0.0

1.0

2.0
3.0
Fatigue D am age

4.0

5.0

0.0

1.0

Fig. 1(a) Comparison of Fatigue Damages of DSS BCs

PAGE 122 OF 171

2.0
Fatigue D am age

3.0

4.0

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

S1

S3

S7

25

25

15

15

10

C urrent
M odified20
V erticalLocation (m )V erticalLocation (m )V erticalLocation (m )20

10

C urrent
M odified

5

5

15

10

C urrent
M odified

5

0

0
0.0

1.0
2.0
Fatigue D am age

3.0

0
0.0

1.0

2.0
Fatigue D am age

3.0

4.0

0.0

2.0
4.0
Fatigue D am age

6.0

Fig. 1(b) Comparison of Fatigue Damages of SSS BCs
3.3 Scantling impact due to the change in Chapter 8, Section 4, [2.3.3] and [3.3.3]
3.3.1 Procedure for impact calculation(1) Original scantlings of side longitudinals are checked by the requirement of Ch 6, Sec 2 of theRules. If the original scantlings do not meet the requirement of Ch 6, Sec 2, the modified
scantlings are considered.
(2) Fatigue check for the longitudinals with modified scantlings is carried out by the current CSR.
(3) Scantling impact in terms of sectional area due to fatigue check is evaluated.
(4) Fatigue check for the longitudinal with the modified scantling is carried out by the proposed
requirement.
(5) Scantling impact in terms of sectional area due to the proposed fatigue check requirement isevaluated.
3.3.2 Scantling impact due to proposed fatigue check requirement
The scantling impact in terms of sectional area of longitudinal is evaluated according to theprocedure mentioned above for D1 ship and S1 ship for an example and the results are given in
Table 2 and 3.
Table 2 Scantling impact of side longitudinals for D1 shipsID

1 (Upper)
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21(Lower)
Average

Scantling impact
according to therequirement in Ch
6 Sec 2
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%

Current Rule
Cumulative
fatiguedamage
1.25
0.64
1.09
0.94
0.94
1.25
1.92
2.21
2.35
1.85
1.15
0.95
0.61
0.23
0.16
0.17
0.18
0.39
0.53
0.08
0.62
-

Scantling effect due
to fatigue check0.0% (IA to T-type)
0.0%
+2.3%
0.0%
0.0%
+9.3%
+23.7%+20.6%+23.9%+13.7%
+4.9%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
4.3% up

Cumulative
fatiguedamage
0.79
0.45
0.62
0.50
0.27
0.11
0.39
0.45
0.48
0.49
0.41
0.34
0.23
0.04
0.04
0.05
0.06
0.40
0.55
0.09
0.65
-

PAGE 123 OF 171

Proposed Rule
Scantling effect due tofatigue check0.0% (T-type to IA)
0.0%
-2.3%
0.0%
0.0%
-9.3%
-23.7%-20.6%-23.9%-13.7%
-4.9%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-4.3%

Scantling
impact due tomodification
0.0%
0.0%
-2.3%
0.0%
0.0%
-9.3%
-23.7%-20.6%-23.9%-13.7%
-4.9%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-4.3%

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Table 2 Scantling impact of side longitudinals for S1 shipsID

1 (Upper)
2
3
4
5
6
7
8
9
10(Lower)
Average

Current Rule
Scantling impact
according to therequirement in Ch 6 Sec 2
+8.4%
+5.8%
+27.9%+23.8%+28.0%+29.0%+26.5%+26.5%+30.9%+30.9%
23.8% up

Cumulative
fatigue damage
0.64
0.54
0.81
0.74
0.76
1.21
1.10
1.20
1.54
1.33
-

Scantlingeffect due tofatigue check
0.0%
0.0%
0.0%
0.0%
0.0%
+5.3%
+3.2%
+6.2%
+17.0%+12.1%+4.4%

Proposed Rule
Cumulative
fatigue damage
0.52
0.42
0.54
0.45
0.53
1.21
1.10
1.20
1.54
1.33
-

Scantling effectdue to fatigue
check
0.0%
0.0%
0.0%
0.0%
0.0%
+5.3%
+3.2%
+6.2%
+17.0
+12.1%+4.4%

Scantling
impact due tomodification
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%

For double side skin bulk carrier whose side structure is longitudinal frame system, scantlingsof a few side longitudinals located below the load water line are affected by the rule change
proposal.
For singe side skin bulk carriers, fatigue check result for side longitudinals in top side tanklocated above load water line are affected by the rule change proposal, however, there is no
scantling impact due to the rule change proposal where side longitudinals have the scantlings
satisfied with the requirements of Ch 6, Sec 2.

4．Technical Background
Technical backgrounds of nonlinear effect on wave pressure and stress concentration factor of
longitudinal end connection are described in Annex 1 and Annex 2, respectively.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

Annex 1: Technical background of nonlinear effect on wave pressure
1. Current Treatment of mean stress
In the current rule, correction factor for the non linearity of the wave pressure range isintroduced to define an equivalent linear long term distribution of stress range which gives a fatigue
damage equivalent to the damage according to the nonlinear distribution of stress range. Fig. 1-1
shows the calculated correction factor in accordance with the distance from the base line.

Fig. 1-1 Correction Factor for Non Linearity of the Wave Pressure Range
By multiplying this correction factor by the linear wave pressures for wave crest and wave
trough conditions, wave pressure range considering non linear effect can be obtained from thedifference of both pressures. In the current rule, because the mean value of the fluctuating pressure
is evaluated as the mean of the pressures for wave crest and wave trough conditions, negative
pressure will work at the position above water line as shown in Fig. 1-2.

Fig. 1-2 Current Condition of Fluctuating Non Linear Pressure
2. Correct Treatment of Mean Stress
Since the negative pressure is not acting at the position above waterline due to the wave
fluctuation, the actual fluctuation of nonlinear pressure is illustrated as Fig. 1-3.

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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Fig. 1-3 Actual Condition of Fluctuating Non Linear Pressure
In order to reflect above mentioned condition of fluctuating nonlinear pressure, the equation
specified in Ch 8, Sec 4, [2.3.3] is to be modified as below:⎛ 6x f 6x f 2 ⎞+ 2 ⎟K gl K s pCW , i j ( k ) sl 2 ⎜1 −
⎜
l
l ⎟⎠
⎝
⋅10 3
σ LW , i j ( k ) =12 w⎧2C NE , i1( k ) pW , i1( k ) ; C NE , i1( k ) < 0.5
pCW , i1( k ) = ⎨; C NE , i1( k ) ≥ 0.5⎩ pW , i1( k ); C NE , i 2( k ) < 0.5; C NE , i 2( k ) ≥ 0.5⎧0pCW , i 2( k ) = ⎨⎩ 2C NE , i 2( k ) − 1 pW , i 2( k )(( j = 1, 2))

According to this modification, the evaluated wave induced stress condition of the stiffeners canbe illustrated as Fig. 1-4. The magnitude of stress range hold same as the one by current rule. Only
the evaluation of mean stress considering the non linearity of the wave pressure has been improved.
45

Negative
Mean StressStress Range
LWL

0

- 10

-5

0

5

10

15

20

Fig. 1-4 Wave induced Stress Condition along Ship Side
In order to take the nonlinear fluctuating pressure condition into account in the evaluation ofmean stress, the equation specified in Ch 8, Sec 4, [3.3.3] is to be modified as below:

PAGE 126 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

2
p CW , i 1( k ) + p CW , i 2( k ) ⎫ 2 ⎛ 6 x f 6 x f ⎞⎧⎜⎟K gl K s ⎨ p S , ( k ) +
s
l
1
−
+
⎬ ⎜
2 ⎟
l
2
l
⎩
⎭ ⎝
⎠
σ LS , ( k ) =⋅ 10 312w+ p CW , i 2( k )p
If fluctuating pressure is linear, p S , ( k ) + CW , i 1( k )= p S , ( k ) , then, above equation would
2

be same as the current equation.

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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Annex 2: Technical background of stress concentration factors for the
stiffeners end connection
SCFs(Stress Concentration Factors) in Table 1 of Ch 8, Sec 4, CSR for Bulker are the ratio of the
hot spot stress obtained by the very fine FE analysis to the nominal stress calculated by the simple
formulae.
1. FE analysis
Considering difference of the stiffener end connection detail, following 2 kinds of hot spot stressare calculated for each detail Nos.1-14.
: hot spot stress due to out-of-plane load
σgl_hotspot: hot spot stress due to forced displacement
σdF_hotspot, σdA_hotspot
1.1 Analysis model
The T type longitudinal stiffener with shell penetrating Transverse Bulkhead is considered.
According to each detail number in Table 1 of Ch 8, Sec 4, CSR for Bulker, the hot spot stresses(position ‘a’ and position ‘f’) at stiffener end connection are calculated.
Fig. 2-1 shows the analysis model and the size of stiffener. Fig. 2-2 shows the stiffener end
connection of each detail No.

(a) Analysis model
Stiffener Size (mm)
h
tw
wf
Tf
500
12.5 150
22

S
850

ts
18

Moment of inertia
I= 99,482 (cm4)
Section modulus
Z= 2,507 (cm3)Span length l0= 5,000 (mm)(b)
Stiffener shape and size
Fig. 2-1 Analysis model and Stiffener details

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

Flat Bar Partdetail no

a/b

b/h

c/d

d/h

R1/b
1
3
4
5
6
7
8

b

b

detail no
9
10
11
12
13
14

1.0
0.4
1.0
1.0
0.36
0.4
0.4

a/b
0.29
0.33
0.29
0.33
0.29
0.33

b/h
1.4
1.2
1.4
1.2
1.4
1.2

0.4
1.0
0.4
0.4
1.1
1.0
1.0

R2/d

0.7
0.7
0.7
0.7
0.7
0.7

1.3

Tripping Bracket Part
e/b
c/d
d/h
R1/b

R2/d

0.7
0.7

1.5

0.75

1.5

0.75

1.5

0.75

1.0
1.0
1.0
1.0
1.0

1.0
1.0
1.0
1.0

1.0
1.0
0.9
0.9

1.3

1.22
1.22

r
（mm
）
30
50
50
50
50
50
50

r(mm)
50
50
50
50
50
50

Fig. 2-2 Stiffener end connection of each detail number
1.2 Loadsa) Out-of-plane loading
A certain out-of-plane uniformly distributing load is loaded, which makes the nominal stress ofstiffener end connection 200N/mm2 in tension side at l0=5m, xf=0. Fig. 2-3 shows the loading
condition of a).
Considering the bracket size (shown in Fig. 2-2), the hot spot stress of stiffener end connection,
σgl_hotspot, is analyzed for each detail No.
b) Forced displacement
Forced displacement (23.7mm) is added to the position (A) or (E) in Fig. 2-1, which makes also
the nominal stress of stiffener end connection 200N/mm2 in tension side at l0=5m, xf=0.
Considering the bracket size, the hot spot stresses of stiffener end connection, σdF_hotspot, σdA_hotspot,
are analyzed for each detail No (shown in Fig. 2-2).

Fig. 2-3 Loading condition
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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

COMMON STRUCTURAL RULES FOR BULK CARRIERS

1.3 Boundary condition
The boundary conditions at each position in each analysis load condition are shown in Table 2-1.
In this Table, (a) means out-of-plane loading, and the others mean forced displacement. The
position (A) to (E) is shown in Fig. 2-1.
Table 2-1 Boundary condition
PositionLoadcondition
(a)
(b1)
(b2)

(A)
Complete
restraint
Y: Forced
displacement
Complete
restraint(B)
Symmetry
Symmetry
Symmetry

(C)

(D)

(E)

Complete
restraint
Complete
restraint
Complete
restraint

Y: Rotation
restraint
Y: Rotation
restraint
Y: Rotation
restraint

Complete
restraint
Complete
restraint
Y: Forced
displacement

2. Simple beam formulae
The beam model shown in Fig. 2-1 and Fig. 2-2 is considered as well as FE analysis, whose
nominal stress of the stiffener end connection is set 200N/mm2 in tension side at l0=5m, xf=0 by
out-of-plane load or forced displacement. Considering the effect of modified span length (lf) andchange of hot spot position by xf specified in Ch 8, Sec 4, CSR for Bulker, following 2 kinds ofmodified nominal stress are calculated for each detail No.1-14.
: modified nominal stress due to out-of-plane load
σgl_nominal: modified nominal stress due to forced displacement
σdF_nominal, σdA_nominala) Out-of-plane loading
Considering the bracket size (shown in Fig. 2-2), the modified nominal stress, σgl_nominal, for eachdetail No is calculated according to the following equation.
2
2⎛ l f ⎞ ⎛⎜ 6 x f 6 x f ⎞⎟σ gl − no min al = σ 0 ⎜⎜ ⎟⎟ 1 −+ 2(σ 0 = 200 N / mm2 , l0 = 5.0m)
⎜
⎟
l0
l0 ⎠
⎝ l0 ⎠ ⎝b) Forced displacement
Considering the bracket size (shown in Fig. 2-2), the modified nominal stresses, σdF_nominal,
σdA_nominal, are calculated according to the following equations. The value of relative
displacement (δF, δA) is 23.7mm.
x fA ⎞ − 5
1.95δ F EI ⎛⎜
⎟10
1
1
.
15
−
σ dF − a _ no min al =
2
⎜
lf ⎟
wl f
⎝
⎠
x fA ⎞ − 5 0.9δ AEI x fA − 5
1.95δ A EI ⎛⎜⎟10 −−σ dA − a _ no min al =
1
1
.
15
10
2
3
⎜
lf ⎟
wl f
wl
f
⎝
⎠
x fF ⎞ − 5 0.9δ FEI x fA − 5
1.95δ F EI ⎛⎜⎟10 −−σ dF − a _ no min al =
1
1
.
15
10
2
3
⎜
lf ⎟
wl f
wl
f
⎝
⎠
x fF ⎞ − 5
1.95δ A EI ⎛⎜
⎟10
−
1
1
.
15
σ dA − f _ no min al =
2
⎜
lf ⎟
wl f
⎝
⎠
Usually, the dimension and the length of the stiffener fitted at fore of transverse bulkhead is thesame of those fitted at after of transverse bulkhead, but there are some cases where they are
different between fore part and after part. Then, taking into account the cases of l f ≠ l a and

PAGE 130 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

I A ≠ I F in order to generalize to the formula mentioned above, the equations specified in 3.3.6 of
Ch 8, Sec 4, CSR for Bulker can be obtained.
3. Results and SCF calculation

Table 2-2 shows the hot spot stress obtained by FE analysis and the modified nominal stresscalculated by simple formulae.
As the values of SCFs for web stiffener connection depend on the analytical model, boundary
condition, definition of hot spot stress, etc., each classification society specifies the different SCFs.
In CSR for Bulker, in order to set up the single SCFs, we decided that the SCFs for Kgl_in detailNo. 1 to 8 specified in BV rule were used. (See Table 2-2) The other SCFs in detail No. 1 to 8 wereobtained by multiplying the ratio (5) in Table 2 by the value calculated by FEA.
For SCFs for tripping brackets connections in detail No. 9 to 14, the averaged ratio (5) in Table 2
which is equal to 0.83 was considered.
Furthermore, the modified SCFs value obtained by multiplying the SCFs specified in Table 2 by
the correction factor is modified by the following manner.
(a) Minimum value is set to 1.05(b) All values are expressed by 0.05 unit
Finally, SCFs of each detail No. can be obtained as shown in Table 2-3 whose values are used forTable 1 of Ch 8, Sec 4, CSR for Bulker.
Table 2-3 Stress concentration factor
detail
No.
1
3
4
5
6
7
8

point

Kgl

KdF

KdA

point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'

1.50
1.10
1.35
1.05
1.05
1.30
1.05
1.30
1.05
1.05
1.05
1.05
1.05
1.05

1.15
1.55
1.05
1.05
1.05
1.30
1.05
1.50
1.05
1.10
1.05
1.05
1.05
1.10

1.50
1.05
1.30
1.05
1.20
1.05
1.15
1.05
1.05
1.05
1.15
1.05
1.10
1.05

detail
No.
9
10
11
12
13
14

PAGE 131 OF 171

point

Kgl

KdF

KdA

point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'

1.40
1.60
1.30
1.55
1.10
1.75
1.10
1.30
1.05
1.95
1.05
1.70

1.05
1.70
1.05
1.30
1.05
1.40
1.05
1.05
1.05
1.55
1.05
1.15

1.75
1.05
1.75
1.05
1.20
1.05
1.20
1.05
1.15
1.05
1.15
1.05

pointσgl_hot(1)

1point 'a'point 'f'

297.7
217.5

184.3
184.3

point 'a'point 'f'point 'a'point 'f'

299.8
122.6
175.6
275.8

5

point 'a'point 'f'

6
7

3
4

PAGE 132 OF 171

8
9

11
12
13
14

NK’s SCF(3)=(1)/(2)(5)

Modified SCF

(9)
270.1
150.3

167.1
167.1

1.62
0.90

1.50(1.62*0.93)
0.83(0.90*0.93)

1.05(1.30*0.81)
1.02(1.27*0.81)
0.92(1.15*0.80)
1.30(1.63*0.80)

272.4
170.8
253.6
210.1

172.0
162.3
171.7
181.6

1.58
1.05
1.48
1.16

1.28(1.58*0.81)
0.85(1.05*0.81)
1.12(1.40*0.80)
0.93(1.16*0.80)

1.17
1.78

0.99(1.17*0.84)
1.51(1.78*0.84)

214.6
210.0

159.4
174.3

1.35
1.20

1.13(1.35*0.84)
1.01(1.20*0.84)

190.0
186.8

1.19
1.37

0.88(1.19*0.74)
1.01(1.37*0.74)

268.5
208.8

186.8
190.0

1.44
1.10

1.07(1.44*0.74)
0.81(1.10*0.74)

209.9
206.8

179.7
171.7

1.17
1.20

0.88(1.17*0.76)
0.91(1.20*0.76)

264.0
188.1

176.8
176.1

1.49
1.07

1.13(1.49*0.76)
0.81(1.07*0.76)

194.7
206.0
198.5
253.5
193.8
169.8
189.0
282.7
192.2
178.6
167.9
267.8
172.1
176.1

168.3
165.0
154.0
119.3
154.0
109.4
186.3
167.7
186.3
153.3
162.4
142.3
162.4
130.3

1.16
1.25
1.29
2.12
1.26
1.55
1.01
1.69
1.03
1.17
1.03
1.88
1.06
1.35

0.96(1.16*0.83)
1.03(1.25*0.83)
1.07(1.29*0.83)
1.76(2.12*0.83)
1.05(1.26*0.83)
1.29(1.55*0.83)
0.84(1.01*0.83)
1.40(1.69*0.83)
0.85(1.03*0.83)
0.97(1.17*0.83)
0.85(1.03*0.83)
1.56(1.88*0.83)
0.88(1.06*0.83)
1.12(1.35*0.83)

219.8
181.3
320.6
135.4
323.0
121.6
263.7
182.0
263.2
147.8
219.0
172.4
219.3
143.8

163.9
169.1
154.0
129.2
154.0
122.2
182.0
176.1
182.0
165.8
157.3
151.7
157.3
143.1

1.34
1.07
2.08
1.05
2.10
1.00
1.45
1.03
1.45
0.89
1.39
1.14
1.39
1.00

1.11(1.34*0.83)
0.89(1.07*0.83)
1.73(2.08*0.83)
0.87(1.05*0.83)
1.74(2.10*0.83)
0.83(1.00*0.83)
1.20(1.45*0.83)
0.85(1.03*0.83)
1.20(1.45*0.83)
0.74(0.89*0.83)
1.15(1.39*0.83)
0.95(1.14*0.83)
1.15(1.39*0.83)
0.83(1.00*0.83)

(7)

SCF
(6)/(7)(=(4)/(3))

1.62
1.18

1.5

0.93

1.50
1.09(1.18*0.93)

205.5
280.5

167.1
167.1

1.23
1.68

1.14(1.23*0.93)
1.55(1.68*0.93)

179.1
129.0
136.5
169.6

1.67
0.95
1.29
1.63

1.35

0.81

1.35

1.30

0.80

0.77(0.95*0.81)
1.03(1.29*0.80)
1.30

223.7
200.5
200.2
295.7

172.0
158.4
174.6
181.6

1.30
1.27
1.15
1.63

150.5
271.3

123.3
176.7

1.22
1.54

1.30

1.03(1.22*0.84)
1.30

190.9
311.0

163.7
174.3

point 'a'point 'f'

184.5
155.3

123.9
123.9

1.49
1.25

1.10

0.84
0.74

1.10
0.93(1.25*0.74)

226.3
255.3

point 'a'point 'f'

182.9
129.3

132.1
116.7

1.38
1.11

1.05

0.76

1.05
0.84(1.11*0.76)

point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'point 'a'point 'f'

151.0
129.9
311.9
106.5
312.2
42.8
150.6
161.3
152.7
69.2
116.6
159.3
119.0
70.2

119.1
122.6
200.0
55.5
200.0
22.9
113.9
77.4
113.9
44.7
113.7
67.5
113.7
34.9

1.27
1.06
1.56
1.92
1.56
1.87
1.32
2.08
1.34
1.55
1.03
2.36
1.05
2.01

1.05

0.83

1.05
0.88(1.06*0.83)
1.30(1.56*0.83)
1.60(1.92*0.83)
1.29(1.56*0.83)
1.55(1.87*0.83)
1.10(1.32*0.83)
1.73(2.08*0.83)
1.11(1.34*0.83)
1.29(1.55*0.83)
0.85(1.03*0.83)
1.96(2.36*0.83)
0.87(1.05*0.83)
1.67(2.01*0.83)

σdA_hot
(8)

NK’s
SCF
(8)/(9)

(6)

SCF
(4)

Note:
(1) For detail No. 2, the ratio is taken to 0.93.
(2) For detail No. 9-14, the coefficient 0.83 is the average value obtained from the ratios for detail No. 1 to 8.

σdA_nom

COMMON STRUCTURAL RULES FOR BULK CARRIERS

10

σgl_nom(2)

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-6

DetailNo.

Table 2-2 Stress obtained by FE analysis or simple formulae
BV’s Ratio
Modified SCF σdF_hot σdF_nom NK’s
Modified SCF

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-7

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-7(Corrosion Additions)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 133 OF 171

RULE CHANGE NOTICE NO.1-7

COMMON STRUCTURAL RULES FOR BULK CARIIERS

For technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-7.

CHAPTER 3 STRUCTURAL DESIGNPRINCIPLES
Section 3 CORROSION ADDITIONS

1. Corrosion additions
1.2 Corrosion addition determination
1.2.1 Corrosion additions for steel
The corrosion addition for each of the two sides of a structural member, tC1 or tC2, is specified in Tab 1.

The total corrosion addition tC, in mm, for both sides of the structural member is obtained by the following
formula:t C = Roundup 0.5 (t C1 + t C 2 ) + t reserve

For an internal member within a given compartment, the total corrosion addition tC is obtained from thefollowing formula:t C = Roundup 0.5 (2t C1 ) + t reserve

where tC1 is the value specified in Tab 1 for one side exposure to that compartment.
When a structural member is affected by more than one value of corrosion addition (e.g. a plate in a dry bulk
cargo hold extending above the lower zone), the scantling criteria are generally to be applied considering theseverest value of corrosion addition applicable to the member.
In addition, the total corrosion addition tC is not to be taken less than 2 mm, except for web and face plate ofordinary stiffeners.

PAGE 134 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-7

Table 1: Corrosion addition on one side of structural members

Compartment
Type

Ballast watertank (2)Structural member

Face plate ofprimary members
Other members

Transverse
bulkhead

Within 3m below the top oftank (3)Elsewhere
Within 3 m below the top oftank (3)Elsewhere
Upper part (4)Lower stool: sloping plate,vertical plate and top plate
Other parts

Other members

2.0
1.5
1.7
1.2
2.4

1.0

5.2

2.6

3.0

1.5

Webs and flanges of the upperend brackets of side frames ofsingle side bulk carriers
Webs and flanges of lower
brackets of side frames of single
side bulk carriers

1.8

1.0

2.2

1.2

Other parts

2.0

1.2

Upper partDry bulk cargohold (1)Corrosion addition, tC1 or tC2
in mm
BC-A or BC-B
ships withOther
L ≥ 150 m(4)

Sloped plating ofContinuous wooden ceiling2.0
1.2
hopper tank, inner
No continuous wooden ceiling
3.7
2.4
bottom plating
Horizontal member and weather deck (5)1.7
Exposed toatmosphere
Non horizontal member
1.0(7)
Exposed to sea water
1.0
Fuel oil tanks and lubricating oil tanks (2)0.7Fresh water tanks
0.7Spacesnotnormally
accessed,e.g.
accessonly
Void spaces (6)0.7
through bolted manholes openings, pipe tunnels, etc.
Internal of deck houses, machinery spaces, stores
Dry spaces
0.5
spaces, pump rooms, steering spaces, etc.
Other compartments than above
0.5
Notes
(1) Dry bulk cargo hold includes holds, intended for the carriage of dry bulk cargoes, which may carry waterballast.
(2) The corrosion addition of a plating between water ballast and heated fuel oil tanks is to be increased by
0.7 mm.
(3) This is only applicable to ballast tanks with weather deck as the tank top .This is not to be applied tostructural members of inner bottom and located below inner bottom.
(4) Upper part of the cargo holds corresponds to an area above the connection between the top side and theinner hull or side shell. If there is no top side, the upper part corresponds to the upper one third of the
cargo hold height.
(5) Horizontal member means a member making an angle up to 20° as regard as a horizontal line.
(6) The corrosion addition on the outer shell plating in way of pipe tunnel is to be considered as water ballasttank.
(7) Outer side shell between normal ballast draught and scantling draught is to be increased by 0.5 mm.

PAGE 135 OF 171

RULE CHANGE NOTICE NO.1-7

COMMON STRUCTURAL RULES FOR BULK CARIIERS

CHAPTER 9 OTHER STRUCTURES
Section 4 SUPERSTRUCTURES AND DECKHOUSES

Symbols

For symbols not defined in this Section, refer to Ch 1, Sec 4.
L2: Rule length L, but to be taken not greater than 300 m

pD: Lateral pressure for decks, in kN/m2, as defined in [3.2.1]

pSI: Lateral pressure for sides of superstructures, in kN/m2, as defined in [3.2.3]

k: Material factor, defined in Ch 3, Sec 1, [2.2]s: Spacing, in m, of ordinary stiffeners, measured at mid-span along the chordl: Span, in m, of ordinary stiffeners, measured between the supporting members, see Ch 3, Sec 6, [4.2]tC: Corrosion addition, defined in Ch 3, Sec 3c: Coefficient taken equal to:c = 0.75 for beams, girders and transverses which are simply supported on one or both ends
c = 0.55 in other casesma: Coefficient taken equal to:2s ⎡ ⎛s⎞ ⎤sma = 0.204 ⎢4 − ⎜ ⎟ ⎥ , with ≤ 1l ⎢⎣ ⎝ l ⎠ ⎥⎦l

4. Scantlings
4.1 Side plating of non-effective superstructures
4.1.1
The gross thickness, in mm, of the side plating of non-effective superstructures is not to be less than the greaterof the following values:t = 1.21s kp SI + t C

t = 1.21s kp SI + 1.5

t = 0.8 kL

4.2 Deck plating of non-effective superstructures
4.2.1
The gross thickness, in mm, of deck plating of non-effective superstructures is not to be less than the greater ofthe following values:t = 1.21s kp D + t C

t = 1.21s kp D + 1.5

PAGE 136 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-7

t = (5.5 + 0,02 L ) k

where L is not to be taken greater than 200 m.
4.2.2
Where additional superstructures are arranged on non-effective superstructures located on the freeboard deck,

the gross thickness required by [4.2.1] may be reduced by 10%.
4.2.3
Where plated decks are protected by sheathing, the gross thickness of the deck plating according to [4.2.1] and[4.2.2] may be reduced by tC 1.5mm. However, such deck plating is not to be less than 5 mm.
Where a sheathing other than wood is used, attention is to be paid that the sheathing does not affect the steel. The
sheathing is to be effectively fitted to the deck.

4.5 Decks of short deckhouses
4.5.1 Plating
The thickness, in mm, of weather deck of short deckhouses and is not to be less than:t = 8s k + t C

t = 8s k + 1.5

For weather decks of short deckhouses protected by sheathing and for decks within deckhouses, the grossthickness may be reduced by tC 1.5mm. However, such deck plating is not to be less than 5 mm.

5. Superstructure end bulkheads and deckhouse walls
5.3 Scantlings
5.3.2 Plate thickness
The gross thickness of the plating, in mm, is not to be less than the greater of the values obtained from thefollowing formulae:
t = 0.9 s kp Α + t C

t = 0.9 s kp Α + 1.5

L ⎞⎛t min = ⎜ 5.0 + 2 ⎟ k , for the lowest tier
100 ⎠
⎝
L ⎞
⎛
t min = ⎜ 4.0 + 2 ⎟ k , for the upper tiers, without being less than 5.0 mm.
100 ⎠⎝PAGE 137 OF 171

RULE CHANGE NOTICE NO.1-7

COMMON STRUCTURAL RULES FOR BULK CARIIERS

PAGE 138 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-7

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-7(Corrosion Additions)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are, individuallyand collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individually and collectively,
assume no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on theinformation or advice in this document or howsoever provided, unless that person has signed a contract with therelevant IACS Member entity for the provision of this information or advice and in that case any responsibility or
liability is exclusively on the terms and conditions set out in that contract.
PAGE 139 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-7

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for Changes Regarding Corrosion Additions:
1. Reason for the Rule Change
1.1 Note (3) in Table 1 of Ch 3, Sec 3:
The corrosion additions for structural members located within 3m below the top of the tank areenhanced considering the high temperature effect where the tank top is exposed.
Moreover, in the upper part of the bilge hopper tank not connected to the topside tank, the corrosion
additions of structural members in such locations are enhanced considering the possible effect due
to flushing in an air and water mixture environment as specified in KC ID 206.
Hence, the note (3) of Table 1 of the Rules is provided so that the enhanced corrosion addition
is applicable to the structural members in the upper part of the bilge hopper tank.
However, this effect was not evaluated by the statistical thickness measurement data.
In order to evaluate this effect, the corrosion diminutions of the structural members in the upper
part and other parts of the bilge hopper tank not connected to the topside tank are re-examined using
the statistical data which is used for setting up the corrosion additions specified in CSRs.
In the statistical data, 6 ships from among 108 ships have bilge hopper tanks not connected tothe topside tank. The difference of thickness diminution between the structural members in theupper and lower parts of the bilge hopper tank is given in Table 1.

Table 1 Difference of thickness diminution of structural members in bilge hopper tank.
95 percentile value (mm)Average (mm)(Upper) – (Lower)(Upper) – (Lower)
A (21-years)
-0.14
-0.9
B (16-years)
-0.20
-0.8
C (8-years)
0.10
0.1
C (16-years)
0.00
0.0
D (12-years)
-0.04
-0.4
E (11-years)
-0.07
-0.4
F (9-years)
0.00
-0.1
The results in Table 1 show that the thickness diminution of structural members in the upper
part of the bilge hopper tank is rather small compared to those in the lower part.
Therefore, the note (3) of Table 1 of the Rules should be revised according to this result.
1.2 Ch 9, Sec 4
According to the requirements in Ch 3, Sec 2, [2.1.1] and Ch 9, Sec 4, [1.2.1], the scantlings ofstructural members in superstructures and deckhouses are gross. However, corrosion additions
based on the net scantling approach specified in Ch 3, Sec 1, [2.2] are referred in “Symbols” andrequired thickness formula. This was not the intention of these requirements which come from GL
rules.

2. Summary of the Rule Change
2.1 Note (3) in Table 1 of Ch 3, Sec 3
The structural members located within 3m below the top of the tank where the tank top is
exposed to the weather deck is applicable to the enhanced corrosion additions specified in Table 1of the Rules.

PAGE 140 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-7

2.2 Ch 9, Sec 4
In all required thickness formulae, “tc” is changed to the absolute value, i.e., 1.5mm. In addition,
the word “thickness” is changed to “gross thickness” for clarification.

3. Impact on scantlings
3.1 Note (3) in Table 1 of Ch 3, Sec 3
As the corrosion additions on one side of structural members within 3m below the top of the bilge
hopper tank is changed to 1.2mm from 1.7mm, thicknesses of side shell and sloping plate andscantlings of longitudinals and transverses within 3m of the bilge hopper tank are reduced
accordingly.
3.2 Ch 9, Sec 4
The gross thicknesses in superstructures and deckhouses are reduced by 0.5mm.

PAGE 141 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-7

PAGE 142 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSCOMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-8

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-8(Corrugated Bulkhead)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 143 OF 171

RULE CHANGE NOTICE NO.1-8

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-8.

CHAPTER 3 STRUCTURAL DESIGNPRINCIPLES
Section 6 STRUCTURAL ARRANGEMENT PRINCIPLES

6. Double bottom
6.4 Floors
6.4.2 Floors in way of transverse bulkheads
Where transverse bulkhead is provided with lower stool, solid floors are to be fitted in line with both sides oflower stool. Where transverse bulkhead is not provided with lower stool, solid floors are to be fitted in line withboth flanges of the vertically corrugated transverse bulkhead or in line of plane transverse bulkhead.
The net thickness and material properties of the supporting floors and pipe tunnel beams are to be not less thanthose required for the bulkhead plating or, when a stool is fitted, of the stool side plating.

10. Bulkhead structure
10.4 Corrugated bulkheads
10.4.2 Construction

The main dimensions a, R, c, d, t, ϕand sC of corrugated bulkheads are defined in Fig 28.
The bending radius is not to be less than the following values, in mm:
R = 3.0t
where :t

: As-built thickness, in mm, of the corrugated plate.

The corrugation angle ϕ shown in Fig 28 is to be not less than 55°.
The thickness of the lower part of corrugations is to be maintained for a distance from the inner bottom (if nolower stool is fitted) or the top of the lower stool not less than 0.15lC.
The thickness of the middle part of corrugations is to be maintained for a distance from the deck (if no upperstool is fitted) or the bottom of the upper stool not greater than 0.3lC.
The section modulus of the corrugations in the remaining upper part of the bulkhead is to be not less than 75% ofthat required for the middle part, corrected for different minimum yield stresses.
When welds in a direction parallel to the bend axis are provided in the zone of the bend, the welding procedures
are to be submitted to the Society for approval.

PAGE 144 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSRULE CHANGE NOTICE NO.1-8

a
c

tf
R

ϕ ≥ 55 otwdsC

Figure 28: Dimensions of a corrugated bulkhead

10.4.5 Structural arrangements
The strength continuity of corrugated bulkheads is to be ensured at the ends of corrugations.

Where corrugated bulkheads are cut in way of primary supporting members, attention is to be paid to ensure
correct alignment of corrugations on each side of the primary member.
Where vertically corrugated transverse bulkheads or longitudinal bulkheads are welded on the inner bottom
plate, floors or girders are to be fitted in way of flanges of corrugations, respectively and the net thickness andmaterials of floors and girders are to be not less than those adjacent corrugation face plate.
In general, the first vertical corrugation connected to the boundary structures is to have a width not smaller thantypical width of corrugation flange.
Where stools are fitted at the lower part of transverse bulkheads, the net thickness of adjacent floors is to be notless than that of the stool plating.
10.4.6 Bulkhead stools
Plate diaphragms or web frames are to be fitted in bottom stools in way of the double bottom longitudinal girders

or plate floors, as the case may be.
Brackets or deep webs are to be fitted to connect the upper stool to the deck transverse or hatch end beams, as
the case may be.
The continuity of the corrugated bulkhead with the stool plating is to be adequately ensured. In particular, upper
strake of the lower stool is to be of the same net thickness and yield stress as those of the lower strake of thebulkhead.
10.4.7 Lower stool
The lower stool, when fitted, is to have a height in general not less than 3 times the depth of the corrugations.

The net thickness and material of the stool top plate are to be not less than those required for the bulkhead
plating above. The thickness and material properties of the upper portion of vertical or sloping stool side plating
within the depth equal to the corrugation flange width from the stool top are to be not less than the required
flange plate thickness and material to meet the bulkhead stiffness requirement at the lower end of the corrugation.
The ends of stool side ordinary stiffeners, when fitted in a vertical plane, are to be attached to brackets at theupper and lower ends of the stool.
The distance d from the edge of the stool top plate to the surface of the corrugation flange is to be in accordancewith Fig 30.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSThe stool bottom is to be installed in line with double bottom floors or girders as the case may be, and is to havea width not less than 2.5 times the mean depth of the corrugation.
The stool is to be fitted with diaphragms in line with the longitudinal double bottom girders or floors as the casemay be, for effective support of the corrugated bulkhead. Scallops in the brackets and diaphragms in way of theconnections to the stool top plate are to be avoided.
Where corrugations are cut at the lower stool, corrugated bulkhead plating is to be connected to the stool top
plate by full penetration welds. The stool side plating is to be connected to the stool top plate and the inner
bottom plating by either full penetration or deep penetration welds. The supporting floors are to be connected tothe inner bottom by either full penetration or deep penetration weld.

Figure 30: Permitted distance, d, from the edge of the stool top plate to the surface of thecorrugation flange
10.4.8 Upper stool

The upper stool, when fitted, is to have a height in general between two and three times the depth of corrugations.
Rectangular stools are to have a height in general equal to twice the depth of corrugations, measured from thedeck level and at the hatch side girder.
The upper stool of transverse bulkhead is to be properly supported by deck girders or deep brackets between theadjacent hatch end beams.
The width of the upper stool bottom plate is generally to be the same as that of the lower stool top plate. The
stool top of non-rectangular stools is to have a width not less than twice the depth of corrugations.
The thickness and material of the stool bottom plate are to be the same as those of the bulkhead plating below.
The thickness of the lower portion of stool side plating is to be not less than 80% of that required for the upper
part of the bulkhead plating where the same material is used.
The ends of stool side ordinary stiffeners when fitted in a vertical plane, are to be attached to brackets at theupper and lower end of the stool.
The stool is to be fitted with diaphragms in line with and effectively attached to longitudinal deck girders
extending to the hatch end coaming girders or transverse deck primary supporting members as the case may be,for effective support of the corrugated bulkhead.
Scallops in the brackets and diaphragms in way of the connection to the stool bottom plate are to be avoided.
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10.4.9 Alignment
At deck, if no upper stool is fitted, two transverse or longitudinal reinforced beams as the case may be, are to be

fitted in line with the corrugation flanges.
At bottom, if no lower stool is fitted, the corrugation flanges are to be in line with the supporting floors or
girders.
The weld of corrugations and floors or girders to the inner bottom plating are to be full penetration ones. The
thickness and material properties of the supporting floors or girders are to be not less than those of thecorrugation flanges. Moreover,Tthe cut-outs for connections of the inner bottom longitudinals to double bottom floors are to be closed by collar
plates. The supporting floors or girders are to be connected to each other by suitably designed shear plates.
Stool side plating is to be aligned with the corrugation flanges. Lower stool side vertical stiffeners and theirbrackets in the stool are to be aligned with the inner bottom structures as longitudinals or similar, to provide
appropriate load transmission between these stiffening members.
Lower stool side plating is not to be knuckled anywhere between the inner bottom plating and the stool top plate.
10.4.13 Section modulus at the lower end of corrugations(void)a) The section modulus at the lower end of corrugations (Fig 31 to Fig 35) is to be calculated with thecompression flange having an effective flange width bef not larger than that indicated in [10.4.10].
b) Webs not supported by local brackets
Except in case e), if the corrugation webs are not supported by local brackets below the stool top plate (orbelow the inner bottom) in the lower part, the section modulus of the corrugations is to be calculated
considering the corrugation webs 30% effective.
c) Effective shedder plates
Provided that effective shedder plates, as defined in [10.4.11], are fitted (see Figs 31 and 32), whencalculating the section modulus of corrugations at the lower end (cross sections 1 in Figs 31 and 32), the areaof flange plates may be increased by the value obtained, in cm2, from the following formula:
I SH = 2.5a t f t SH

without being taken greater than 2.5atf,
where:: Width, in m, of the corrugation flange (see Fig 28)

atSH : Net shedder plate thickness, in mm: Net flange thickness, in mm.

tfd) Effective gusset plates
Provided that effective gusset plates, as defined in [10.4.12], are fitted (see Figs 33 to 35), when calculating
the section modulus of corrugations at the lower end (cross-sections 1 in Figs 33 to 35), the area of flange
plates may be increased by the value obtained, in cm2, from the following formula:
I G = 7hG t f

where:hG: Height, in m, of gusset plates (see Figs 33 to 35), to be taken not greater than (10/7)SGU

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SGU : Width, in m, of gusset platestfe): Net flange thickness, in mm

Sloping stool top plate
If the corrugation webs are welded to a sloping stool top plate which has an angle not less than 45° with thehorizontal plane, the section modulus of the corrugations may be calculated considering the corrugation
webs fully effective. For angles less than 45°, the effectiveness of the web may be obtained by linear
interpolation between 30% for 0° and 100% for 45°.
Where effective gusset plates are fitted, when calculating the section modulus of corrugations the area offlange plates may be increased as specified in d) above. No credit may be given to shedder plates only.

hG

shedder plate①
lower stool

Figure 31: Symmetrical shedder plates (void)

shedder platehG①
lower stool

Figure 32: Asymmetrical shedder plates (void)

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gusset platehG①
lower stool

Figure 33: Symmetrical gusset/shedder plates (void)

gusset platehG①
lower stool

Figure 34: Asymmetrical gusset/shedder plates (void)

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COMMON STRUCTURAL RULES FOR BULK CARRIERS

①

hG

=
=
lower stool

Figure 35: Asymmetrical gusset/shedder plates (void)10.4.14 Section modulus at sections other than the lower end of corrugations(void)The section modulus is to be calculated with the corrugation webs considered effective and the compression
flange having an effective flange width, bef, not larger than that obtained in [10.4.10].
10.4.15 Shear area

(void)The shear area is to be reduced in order to account for possible non-perpendicularity between the corrugation
webs and flanges. In general, the reduced shear area may be obtained by multiplying the web sectional area by(sin ϕ), ϕ being the angle between the web and the flange (see Fig 28).

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CHAPTER 6 HULL SCANTLING

Section 1 PLATING
3. Strength check of plating subjected to lateral pressure
3.2 Plating thickness
3.2.3 Net thickness of the corrugations of transverse vertically corrugated watertight bulkheads
separating cargo holds for flooded conditions
The net plate thickness t, in mm, of transverse vertically corrugated watertight bulkheads separating cargo holds

is to be not less than that obtained from the following formula:t = 14.9s

1.05 pReH

p: Resultant pressure, in kN/m2, as defined in Ch 4, Sec 6, [3.3.7]

s: plate width, in m, to be taken equal to the width of the corrugation flange or web, whichever is greater.

For built-up corrugation bulkheads, when the thicknesses of the flange and web are different:•

the net thickness of the narrower plating is to be not less than that obtained, in mm, from the following
formula:t N = 14.9s

s•

1.05 pReH: plate width, in m, of the narrower plating
the net thickness of the wider plating is not to be less than the greater of those obtained, in mm, from thefollowing formulae:tW = 14.9s

tW =1.05 pReH

462 s 2 p 2− t NP
ReH

where:tNP: Actual net thickness of the narrower plating, in mm, to be not taken greater than:t NP = 14.9 ss1.05 pReH: plate width, in m, to be taken equal to the width of the corrugation flange or web, whichever is greater.

The net thickness of the lower part of corrugations is to be maintained for a distance from the inner bottom (if nolower stool is fitted) or the top of the lower stool not less than 0.15lC, where lC is the span of the corrugations,in m, to be obtained according to Ch 3, Sec 6, [10.4.4]. The net thickness is also to comply with the requirements
in [3.2.1], Sec 2, [3.6.1 & 3.6.2], and Sec 3, [6].

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COMMON STRUCTURAL RULES FOR BULK CARRIERSThe net thickness of the middle part of corrugations is to be maintained for a distance from the deck (if no upperstool is fitted) or the bottom of the upper stool not greater than 0.3lC. The net thickness is also to comply withthe requirements in [3.2.1] and Sec 2, [3.6.1& 3.6.2].

Figure 5: Parts of Corrugation

3.2.3 bis1 Net thickness of lower stool and upper stool
The net thickness and material of the stool top plate of lower stool are to be not less than those for the corrugatedbulkhead plating above required by [3.2.3].
The net thickness and material of the upper portion of vertical or sloping stool side plating of lower stool within
the depth equal to the corrugation flange width from the stool top are to be not less than the flange plate at thelower end of the corrugation required by [3.2.3], as applicable, whichever is the greater.
The net thickness and material of the stool bottom plate of upper stool are to be the same as those of thebulkhead plating below required by [3.2.3], as applicable, whichever is the greater.
The net thickness of the lower portion of stool side plating is to be not less than 80% of the upper part of thebulkhead plating required by [3.2.3], as applicable, whichever is the greater, where the same material is used.
The net thicknesses of lower stool and upper stool are to be not less than those required by [3.2.1], [3.2.2] and[3.2.4].
3.2.3 bis2 Net thickness of supporting floors of corrugated bulkhead
The net thickness and material of the supporting floors and pipe tunnel beams of corrugated bulkhead, when nostool is fitted, are to be not less than those of the corrugation flanges required by [3.2.3]
When a lower stool is fitted, the net thickness of supporting floors are to be not less than that of the stool side
plating required by the first sentence of [3.2.2].

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3.2.4 Testing conditions
The plating of compartments or structures as defined in Ch 4, Sec 6, [4] is to be checked in testing conditions. To

this end, its net thickness is to be not less than the value obtained, in mm, from the following formula:t = 15.8ca cr s

pT
1.05 RY

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Section 2 ORDINARY STIFFENERS
2. General requirements
2.1 Corrugated bulkhead (void)
2.1.1(void)
Unless otherwise specified, the net section modulus and the net shear sectional area of a corrugation are to be notless than those obtained for an ordinary stiffener with s equal sC, as defined in Fig 2.

a
c

tf
R

ϕ ≥ 55 otwdsC

Figure 2: Corrugated bulkhead (void)

3. Yielding check3.2 Strength criteria for single span ordinary stiffeners other than side framesof single side bulk carriers
3.2.4 Net section modulus of corrugated bulkhead of ballast hold for ships having a length L
less than 150m

The net section modulus w, in cm3, of corrugated bulkhead of ballast hold for ships having a length L less than
150m subjected to lateral pressure are to be not less than the values obtained from the following formula:
w=K( p S + pW )s C l 2
mλ S RY

10 3

where:
K: Coefficient given in Tab 4 and 5, according to the type of end connection. When dH < 2.5d0 , both
section modulus per half pitch of corrugated bulkhead and section modulus of lower stool at inner
bottom are to be calculated.

sC: Half pitch length, in m, of the corrugation, defined in [2.1.1] Ch 3, Sec 6, Fig 28

λ: Length, in m, between the supports, as indicated in Fig 6

λS: Coefficient defined in Tab 3.

The effective width of the corrugation flange in compression is to be considered according to Ch3, Sec 6,[10.4.10] when the net section modulus of corrugated bulkhead is calculated.

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Table 4: Values of K, in case d H ≥ 2.5d 0Upper end
Lower end

Supported bygirders

Welded directly
to deck

Welded to stool efficiently
supported by ship structure

Supported by girders or welded
directly to decks or inner bottoms
Welded to stool efficiently
supported by ship structure

0.83

1.25

1.25

1.25

1.00

0.83

Upper end support
Supported by girders

Welded directly to deck

Welded to stool efficiently
supported by ship structure

1.25

1.00

0.83

Table 5: Values of K, in case d H < 2.5d 0Upper end support

Supported by girders

Connected to deck

Connected to stool

Section modulus of corrugatedbulkhead
Section modulus of stool atbottom

0.83

0.71

0.65

0.83

1.25

1.13

Upper end support

Section modulus of
Supported by girders

Connected to Deck

Connected to stool

Corrugated bulkhead

0.83

0.71

0.65

Stool at bottom

0.83

1.25

1.13

d H ≥ 2.5d 0

d H < 2.5d 0

B

B
e

A

d0

e

A

d0

l

dH

dH
e = A(1 − d 0 / 2 B )Figure 6: Measurement of l

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3.2.6 Bending capacity and shear capacity of the corrugations of transverse verticallycorrugated watertight bulkheads separating cargo holds for flooded conditions (void)
The bending capacity and the shear capacity of the corrugations of watertight bulkheads between separatingcargo holds are to comply with the following formulae:
0.5W LE + W M ≥

τ≤

M
10 3
0.95ReH

ReH
2

where:
M : Bending moment in a corrugation, to be obtained, in kN.m, from the following formula:
M = FlC / 8
F : Resultant force, in kN, to be calculated according to Ch 4, Sec 6, [3.3.7]
lC : Span of the corrugations, in m, to be obtained according to Ch 3, Sec 6, [10.4.4]

WLE : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the lower end of thecorrugations according to Ch 3, Sec 6, [10.4.13], without being taken greater than the value obtained fromthe following formula:⎛ Q hG − 0.5hG2 sC pG ⎞ 3⎟ 10
WLE ,M = WG + ⎜
⎜
⎟
R
eH
⎝
⎠

WG : Net section modulus, in cm3, of one half pitch corrugation, to be calculated in way of the upper end of
shedder or gusset plates, as applicable, according to Ch 3, Sec 6, [10.4.1413]
Q : Shear force in a corrugation, to be obtained, in kN, from the following formula:Q = 0.8F
hG : Height, in m, of shedders or gusset plates, as applicable (see Ch 3, Sec 6, Fig 31 to Fig 35)
pG : Resultant pressure, in kN/m2, to be calculated in way of the middle of the shedders or gusset plates, asapplicable, according to Ch 4, Sec 6, [3.3.7]
sC : Spacing of the corrugations, in m, to be taken according to Fig 2
WM : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the mid-span of corrugations
according to Ch 3, Sec 6, [10.4.14], without being taken greater than 1.15WLE
τ : Shear stress in the corrugation, in N/mm2, to be obtained from the following formula:τ = 10Q
Ash

Ash : Shear area, in cm2, calculated according to Ch 3, Sec 6, [10.4.15].
3.2.7 Net section modulus and net shear sectional area of single span ordinary stiffeners under
testing conditions

The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of single span ordinary stiffeners
subjected to testing are to be not less than the values obtained from the following formulae:w=

p T sl 2
10 3
1.05mRYAsh =5 p T sl
1.05τ a sin φ

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where:
φ : Angle, in deg, defined in [3.2.3].

3.6 Scantlings of transverse vertically corrugated watertight bulkheads
separating cargo holds for flooded conditions
3.6.1 Bending capacity and shear capacity of the corrugations of transverse verticallycorrugated watertight bulkheads separating cargo holds
The bending capacity and the shear capacity of the corrugations of watertight bulkheads between separatingcargo holds are to comply with the following formulae:
0.5W LE + W M ≥

τ≤

M
10 3
0.95ReH

ReH
2

where:M: Bending moment in a corrugation, to be obtained, in kN.m, from the following formula:
M = FlC / 8

F: Resultant force, in kN, to be calculated according to Ch 4, Sec 6, [3.3.7]

lC: Span of the corrugations, in m, to be obtained according to [3.6.2]

WLE: Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the lower end of thecorrugations according to [3.6.2], without being taken greater than the value obtained from thefollowing formula:⎛ Q hG − 0.5hG2 sC pG ⎞ 3⎟ 10
WLE ,M = WG + ⎜
⎜
⎟
ReH
⎝
⎠

WG

: Net section modulus, in cm3, of one half pitch corrugation, to be calculated in way of the upper end of
shedder or gusset plates, as applicable, according to [3.6.2]

Q: Shear force at the lower end of a corrugation, to be obtained, in kN, from the following formula:Q = 0.8F

hG: Height, in m, of shedders or gusset plates, as applicable (see Fig 11 to Fig 15)

pG: Resultant pressure, in kN/m2, to be calculated in way of the middle of the shedders or gusset plates, asapplicable, according to Ch 4, Sec 6, [3.3.7]

sC: Spacing of the corrugations, in m, to be taken according to Ch 3, Sec 6, Fig 28

WM: Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the mid-span ofcorrugations according to [3.6.2] without being taken greater than 1.15WLE

τ: Shear stress in the corrugation, in N/mm2, to be obtained from the following formula:τ = 10Ash

Q
Ash: Shear area, in cm2, calculated according to the followings.
The shear area is to be reduced in order to account for possible non-perpendicular between thecorrugation webs and flanges. In general, the reduced shear area may be obtained by multiplying the

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COMMON STRUCTURAL RULES FOR BULK CARIIERS

web sectional area by (sin ϕ), ϕ being the angle between the web and the flange (see Ch 3, Sec 6, Fig
28).
The actual net section modulus of corrugations is to be calculated according to [3.6.2].
The net section modulus of the corrugations upper part of the bulkhead, as defined in Sec 1, Fig 5, isto be not less than 75% of that of the middle part complying with this requirement and Sec 1, [3.2.1],
corrected for different minimum yield stresses.
3.6.2 Net Section modulus at the lower end of corrugationsa) The net section modulus at the lower end of corrugations (Fig 11 to Fig 15) is to be calculated with thecompression flange having an effective flange width bef not larger than that indicated in Ch 3, Sec 6, [10.4.10]b) Webs not supported by local brackets
Except in case e), if the corrugation webs are not supported by local brackets below the stool top plate (orbelow the inner bottom) in the lower part, the section modulus of the corrugations is to be calculated
considering the corrugation webs 30% effective.
c) Effective shedder plates
Provided that effective shedder plates, as defined in Ch 3, Sec 6, [10.4.11] are fitted (see Fig 11 and Fig 12),
when calculating the section modulus of corrugations at the lower end (cross sections 1 in Fig 11 and Fig 12),the net area of flange plates may be increased by the value obtained, in cm2, from the following formula:

I SH = 2.5a t f t SH

without being taken greater than 2.5atf,

where:a: Width, in m, of the corrugation flange (see Ch 3, Sec 6, Fig 28)

tSH: Net shedder plate thickness, in mm

tf: Net flange thickness, in mm.

d) Effective gusset plates
Provided that effective gusset plates, as defined in Ch 3, Sec 6, [10.4.12], are fitted (see Fig 13 to Fig 15),
when calculating the net section modulus of corrugations at the lower end (cross-sections 1 in Fig 13 to Fig15), the area of flange plates may be increased by the value obtained, in cm2, from the following formula:
IG = 7hGtf
where:hG: Height, in m, of gusset plates (see Fig 13 to Fig 15), to be taken not greater than (10/7)SGU

SGU : Width, in m, of gusset platestf: Net flange thickness, in mme) Sloping stool top plate
If the corrugation webs are welded to a sloping stool top plate which has an angle not less than 45° with thehorizontal plane, the section modulus of the corrugations may be calculated considering the corrugation webs
fully effective. For angles less than 45°, the effectiveness of the web may be obtained by linear interpolation
between 30% for 0° and 100% for 45°.
Where effective gusset plates are fitted, when calculating the net section modulus of corrugations the net areaof flange plates may be increased as specified in d) above. No credit may be given to shedder plates only.

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shedder platehG

shedder plate

hG

①

①
lower stool

lower stool

Figure 11: Symmetrical shedder plates

Figure 12: Asymmetrical shedder plates

gusset platehGgusset plate①hG
lower stool①
lower stool
Figure 13: Symmetrical gusset/shedder plates

Figure 14: Asymmetrical gusset/shedder plates

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COMMON STRUCTURAL RULES FOR BULK CARIIERS

①

hG

=
=
lower stool

Figure 15: Asymmetrical gusset/shedder plates

3.6.3 Stiffeners in lower stool and upper stool

The net section modulus of stiffeners in lower stool and upper stool is to be greater of the values obtained fromthe following formula or required by [3.2.5].

w=

psl 2
103
16αλs RY

Where,p: Pressure, in kN/m2, as defined in Ch 4 Sec 6, [3.3.7]

α and λs : defined in [3.2.5]

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Section 3 BUCKLING & ULTIMATE STRENGTH OF
ORDINARY STIFFENERS AND STIFFENED PANELS

6. Transverse vertically corrugated watertight bulkhead in flooded
condition
6.1 General
6.1.1 Shear buckling check of the bulkhead corrugation webs

The shear stress τ, calculated according to Ch 6, Sec 2, [3.6.1 3.2.6], is to comply with the following formula:τ ≤ τC
where:
τC: Critical shear buckling stress to be obtained, in N/mm2, from the following formulae:τC =τ E

τC =
τE

for τ E ≤ReH ⎛⎜
ReH ⎞⎟
1−
3 ⎜⎝ 4 3 τ E ⎟⎠for τ E >

ReH
2 3
R eH
2 3

: Euler shear buckling stress to be obtained, in N/mm2, from the following formula:⎛ tw ⎞⎟
3⎝ 10 c ⎠2

τ E = 0 .9 k t E ⎜kt: Coefficient, to be taken equal to 6.34

tW

: Net thickness, in mm, of the corrugation websc

: Width, in m of the corrugation webs (see Ch 3, Sec 6, Fig 28Ch 6, Sec 2, Fig 2).

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COMMON STRUCTURAL RULES FOR BULK CARIIERS

PAGE 162 OF 171

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-8

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-8(Corrugated Bulkhead)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and inthat case any responsibility or liability is exclusively on the terms and conditions set out in that contract.

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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-8

COMMON STRUCTURAL RULES FOR BULK CARRIERSTechnical Background for the Changes regarding CorrugatedBulkhead:
1. Reason for the Rule Change:
There are paragraphs in Ch 3, Sec 6, [10.4] and Ch 6, Sec 1 & 2 where requirements are
specified to transverse vertically corrugated watertight bulkheads separating cargo holds.
However, there are obscure scantling requirements in their application.
It is due to that;- the scantling requirements are included in both chapters which incurs confusion to theuser, and- the application of the requirements is not clearly identified especially for flooded
condition although it was the original intention that IACS UR S18 requirements were to
be incorporated explicitly.
The rule change is prepared in order to resolve this issue by;- shifting the scantling requirements in Ch 3, Sec 6, [10.4] to the appropriate paragraphs in
Ch 6, Sec 2, and- collecting together the scantling requirements for flooded conditions in the newparagraph to be in line with IACS UR S18 requirements, and- only requirements to structural arrangement being remained in Ch 3, Sec 6, [10.4], and- clarifying the cross reference of the related paragraphs.
The answers or interpretations in KC IDs 332, 354, 450 and 580 are taken into
consideration for preparation of this rule change.
In addition, the thickness requirement in Ch 3, Sec 6, [6.4.2] is shifted to Ch 6, Sec 1.

2. Summary of Rule Change
2.1 Ch 3, Sec 6, [6.4.2] and Ch 6, Sec 1, [3.2.3 bis2]
The thickness requirement in Ch 3, Sec 6, [6.4.2] is shifted to Ch 6, Sec 1, [3.2.3 bis2]
with partly modification.
2.2 Ch 3 Sec 6, [10.4.2] “Construction” and Ch 6 Sec 1 [3.2.3]
The scantling requirements in Ch 3, Sec 6, [10.4.2] are deleted and shifted to Ch 6, Sec 1,[3.2.3]. Further in Ch 6, Sec 1, [3.2.3], taking account of the answer in KC ID 332,
- “net” scantling basis is clarified, and- the definition of λc is added,- it is clarified that the net thickness of lowest part of corrugation is to comply with therequirements in [3.2.1], Ch 6, Sec 2, [3.6.1] & [3.6.2] and Ch 6, Sec 3, [6], and,- it is clarified that the net thickness of middle part of corrugation is to comply with therequirements in [3.2.1], Ch 6 and Sec 2, [3.6.1 & 3.6.2]
2.3 Ch 3, Sec 6, [10.4.5], [10.4.6] and [10.4.7], Ch 6, Sec 1, [3.2.3 bis1] and [3.2.4]
The scantling requirements in Ch 3, Sec 6, [10.4.5], [10.4.6] and [10.4.7] are deleted andshifted to Ch 6, Sec 1, [3.2.3 bis1], and “net” scantling basis is clarified and in line with theanswer in KC ID 450 the shifted rule text is modified.
Taking account of the answer in KC ID 332, it is clarified that the required corrugation
flange net plate thickness is according to [3.2.3] or [3.2.4].

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-8

2.4 Ch 3, Sec 6, [10.4.8] Upper stool and Ch 6, Sec 1, [3.2.3 bis1]
The scantling requirements are deleted and shifted to Ch 6, Sec 1 [3.2.3 bis1] and “net”
scantling basis is clarified.
Taking account of the answer in KC ID 332, it is clarified that the bulkhead plating below
the upper stool bottom plating and upper part of the bulkhead plating are according to [3.2.3]
or [3.2.4].
2.5 Ch 3, Sec 6, [10.4.9] Alignment and Ch 6, Sec 1, [3.2.3 bis2]
The scantling requirements in Ch 3, Sec 6, [10.4.9] are deleted and shifted to Ch 6, Sec 1,[3.2.3 bis2], considering the consistency with the requirement in Ch 3, Sec 6, [6.4.2] and“net” scantling basis is clarified.
2.6 Ch 3, Sec 6, [10.4.13] Section modulus at the lower end of corrugations and Ch 6, Sec2, [3.6.2]
The requirement in Ch 3, Sec 6, [10.4.13] is deleted and shifted to the new paragraph Ch 6,
Sec 2, [3.6.2] since it is only related to the scantling requirements for flooded condition.
Further in the new paragraph figure nos. are corrected from “31 thru 35” to “11 thru 15”
accordingly and the cross references in the text are modified.
2.7 Ch 3, Sec 6, [10.4.14] Section modulus at sections other than the lower end of
corrugations and Ch 3, Sec 6, [10.4.15] Shear area
The requirement in Ch 3, Sec 6, [10.4.14] is deleted and shifted to the new paragraph Ch 6,
Sec 2, [3.6.2] (a).
The requirement in Ch 3, Sec 6, [10.4.15] is deleted and shifted to the new paragraph Ch 6,
Sec 2, [3.6.1].
2.8 Ch 6, Sec 2, [2.1.1]
Figure 2 is only applicable when section modulus of corrugated bulkhead is investigatedaccording to Ch 6, Sec 2, [3.2.4]. Figure 2 is same as Ch 3, Sec 6, and Figure 28. In order toavoid user’s misinterpretation Ch 6, Sec 2, [2.1.1] is deleted together with Figure 2.
2.9 Ch 6, Sec 2, [3.2.4], Tables 4 and 5
The definition of the effective width of the corrugation flange is added and Tables 4 and 5
are clarified.
2.10 Ch 6, Sec 2, [3.2.6], Bending capacity and shear capacity of the corrugations oftransverse vertically corrugated watertight bulkheads separating cargo holds forflooded conditions and [3.6]This paragraph is deleted and shifted to the new paragraph Ch 6, Sec 2, [3.6.2] so that all
requirements related to flooded condition are unified together in the new paragraph Ch 6, Sec2, [3.6] and the paragraph Ch 6, Sec 2, [3.6] is newly provided so that the UR S18
requirements can be clearly collected and identified therein. In addition, for determining thenet section modulus of stiffeners in lower stool and upper stool, as it is necessary to consider
the pressure specified in Ch 4, Sec 6, [3.3.7] which comes from IACS UR S18, the newparagraph [3.6.3] is added.
2.11 Ch 6, Sec 3, [6.1.1]
The reference is changed, according to the modification of Ch 6, Sec 2.

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TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-8

COMMON STRUCTURAL RULES FOR BULK CARRIERS

3. Impact on Scantling
Since the subject revisions to the text are:a) the clarification of the text in line with the original intention, orb) the clarification of the texts.
For a) it is not necessary to perform impact study.
For b) it is not possible to perform impact study because the basis is not identified clearly.

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COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-8

Common Structural Rules for
Bulk Carriers, July 2008

Rule Change Notice No.1-9(Main Engine Foundation)
Notes: (1) These Rule Changes enter into force on 1 July 2009.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and in thatcase any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 167 OF 171

RULE CHANGE NOTICE NO.1-9

COMMON STRUCTURAL RULES FOR BULK CARRIERSFor technical background for Rule Changes in this present document, reference is made toseparate document Technical Background for Rule Change Notice No.1-9.

CHAPTER 9 OTHER STRUCTURES

Section 3 MACHINERY SPACE

7. Main machinery seating
7.2 Minimum scantlings
7.2.1
The net scantlings of the structural elements in way of the internal combustion engine seatings are to be obtained

from the formulae in Tab 2. However, the net cross-sectional area of each bedplate of the seatings may be
determined by the engine manufacturers, provided the information regarding permissible foundation stiffness
considering the engine characteristics and engine room arrangement, etc..
Table 2: Minimum scantlings of the structural elements in way of machinery seatings
Scantling minimum value
Net cross-sectional area, in cm2, of each bedplate of the seatings

Bedplate net thickness, in mm

Scantling minimum value

40 + 70P
nr LE

Bedplates supported by two or more girders:
240 + 175

P
nr LE

Bedplates supported by one girder:
5 + 240 + 175

Total web net thickness, in mm, of girders fitted in way ofmachinery seatings

P
nr LE

Bedplates supported by two or more girders:
320 + 215

P
nr LE

Bedplates supported by one girder:

Web net thickness, in mm, of floors fitted in way of machinery
seatings

PAGE 168 OF 171

95 + 65P
nr LE

55 + 40P
nr LE

COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-9

Common Structural Rules for
Bulk Carriers, July 2008

Technical Background forRule Change Notice No.1-9(Main Engine Foundation)

Copyright in these Common Structural Rules for Bulk Carriers is owned by:American Bureau of Shipping
Bureau Veritas
China Classification Society
Det Norske Veritas
Germanischer Lloyd
Korean Register of Shipping
Lloyd's Register
Nippon Kaiji Kyokai
Registro Italiano Navale
Russian Maritime Register of Shipping
Copyright © 2006

The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are,individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individuallyand collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expensecaused by reliance on the information or advice in this document or howsoever provided, unless that person has
signed a contract with the relevant IACS Member entity for the provision of this information or advice and inthat case any responsibility or liability is exclusively on the terms and conditions set out in that contract.

PAGE 169 OF 171

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-9

COMMON STRUCTURAL RULES FOR BULK CARIIERS

Technical Background for the Changes Regarding Main Engine
Foundations
1. Reason for the Rule Change in Ch 9, Sec 3, [7.2]
PT1 was requested to make an interpretation for the usage of Table 2 of the Rule (KC-ID 413).
The scantling according this table leads to very large scantlings, especially the net crosssectional area of engine seatings. This was not the intention of these requirements.
However, the scantling formula except for cross-sectional area of engine seatings specified inTable 2 of the Rules are considered reasonable according to the investigation results ofexisting BCs as given in Figure 1 to Figure 4.
Net Area of Seating

Net Area of Seating

1.40

1.20

1.00

1.00

0.60
0.40

0.80
0.60
0.40

0.20

0.20

0.00

0.00

0

50

100
150
200
Ship's Length (L) (m)250

Actual / Required

1.20

1.00
0.80

300

Net Area of Seating

1.40

1.20
Actual / Required

Actual / Required

1.40

0.80
0.60
0.40
0.20
0.00

0

5000

10000
Engine power (kW)

15000

20000

0.0

5.0

10.0

15.0
P/(Nr*Le)

20.0

25.0

Fig.1 Cross-sectional area of engine seating
Net Thickness of Seating

Net Thickness of Seating

1.60

1.40

1.20

1.20

0.80
0.60

Actual / Required

1.40

1.20
1.00

1.00
0.80
0.60

1.00
0.80
0.60

0.40

0.40

0.40

0.20

0.20

0.20

0.00

0.00

0

50

100

150
200
Ship's Length (L) (m)

250

0.00
0

300

Net Thickness of Seating

1.60

1.40
Actual / Required

Actual / Required

1.60

5000

10000
Engine power (kW)

15000

20000

0.0

5.0

10.0

15.0
P/(Nr*Le)

20.0

25.0

20.0

25.0

20.0

25.0

Fig.2 Net thickness of engine seating
Net Thickness of Girder

Net Thickness of Girder

1.60

1.20

0.80
0.60

Actual / Required

1.40

1.20
Actual / Required

1.40

1.20
1.00

1.00
0.80
0.60

1.00
0.80
0.60

0.40

0.40

0.40

0.20

0.20

0.20

0.00

0.00
0

50

100

150
200
Ship's Length (L) (m)

250

0.00

0

300

Net Thickness of Girder

1.60

1.40

5000

10000
Engine power (kW)

15000

0.0

20000

5.0

10.0

15.0
P/(Nr*Le)

Fig.3 Total net thickness of girders
Net Thickness of Floor

1.60

Net Thickness of Floor

1.60

1.40

1.20

1.20

0.80
0.60

Actual / Required

1.40

1.20
1.00

1.00
0.80
0.60

1.00
0.80
0.60

0.40

0.40

0.40

0.20

0.20

0.20

0.00

0.00

0

50

100

150
200
Ship's Length (L) (m)

250

300

Net Thickness of Floor

1.60

1.40

Actual / Required

Actual / Required

Actual / Required

1.60

0.00
0

5000

10000
Engine power (kW)15000

Fig.4 Net thickness of floors
PAGE 170 OF 171

20000

0.0

5.0

10.0

15.0
P/(Nr*Le)COMMON STRUCTURAL RULES FOR BULK CARRIERSTECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-9

From these results, it is necessary to clarify the dealing with the formula for cross-sectional
area of engine seatings.
In this regard, we considered that it is possible to deal with the drawings supplied by theengine manufactures with information regarding permissible foundation stiffness considering
the engine characteristics and engine room arrangement, etc..

2. Summary of the Rule Change
The scantling of the combustion engine foundation is generally determined by not only the
results of the calculations or experiments for the required foundation stiffness, derived by theengine manufacturer but also the engine room arrangements. It is not the intention of the CSR
for bulk carrier to establish requirements for the combustion engine foundation, which are
more severe than the requirements from the engine manufacturer.
The following examples give an overview of the scantling impact
Therefore, we propose to add the following sentence after the present text of Ch 9, Sec 3,[7.2.1]<Quote>However, the net cross-sectional area of each bedplate of the seatings may be determined by
the engine manufacturers, provided the information regarding permissible foundation stiffness
considering the engine characteristics and engine room arrangement, etc..
<Unquote>

3. Effects and impact on scantling due to this definition
The following table gives an overview of the scantling impact regarding the cross-sectional
area of engine seatings.

PAGE 171 OF 171