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DNVs

Hull Structure course for

World Wide Shipping

9 - Hull Structure cargo area

Transverse Bulkhead

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16.03.2004Slide 2

4.Transverse

bulkhead

Hull Structural Breakdown -

Transverse bulkhead

1. Side

Bottom

Deck

Transverse bulkhead

Longitudinal bulkheadWebframes

2.

3.

4.

5.

6.

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16.03.2004Slide 3

4.Transverse

bulkhead

Structural build up of

transverse bulkhead

Stringers

Transverse bulkheadplating w/stiffeners

Buttress

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16.03.2004Slide 4

4.Transverse

bulkheadStructural functions

Watertight integrity

- Resist internal pressure from cargo and ballast

(cargo boundary)

- Safety against collapse if water ingress (boundary for

flooding)

Hull girder stiffness

- Transverse bulkhead is an important contributor to the

hull girder transverse stiffness

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16.03.2004Slide 5

4.Transverse

bulkheadFunctions of transverse bulkhead

The transverse bulkhead must withstand

internal pressure loads from cargo and ballast

The distribution of cargo and ballast introduces

alternate loading on sections of the transverse

bulkheads (single skin tanker)

Typical fully loaded

condition (single skin)Typical ballast condition

(single skin)

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16.03.2004Slide 6

4.Transverse

bulkheadFunction: tank boundary

Stiffener

Stringer

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16.03.2004Slide 7

4.Transverse

bulkheadFunction: tank boundary

One sided loading on the transverse bulkhead

introduces stresses in the transverse bulkhead as a panel

Bulkhead will flex out and high stresses occur at end

connections towards deck and bottom

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16.03.2004Slide 8

4.Transverse

bulkheadFunction: transverse stiffness

Transverse bulkheads are an important contributor

to the hull girder transverse stiffness

Transversestiffness

Sea

pressure

Sea

pressure

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16.03.2004Slide 9

4.Transverse

bulkheadCharacteristic damages

1. Stringer toes cracking

2. Bottom longitudinal bracket connection to

transverse bulkhead - cracks

3. Cracking of transverse bulkhead stiffenersconnection to stringers

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16.03.2004Slide 10

4.Transverse

bulkheadCracking in stringer toe

Cracks in stringer toes and heel

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16.03.2004Slide 11

4.Transverse

bulkheadCause for cracking in stringer toe

Full cargo tank

Full cargo tankSea

pressure

Compression/tension stresses

from one sided loading

Very high alternating bending stresses in stringer toe

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16.03.2004Slide 12

4.Transverse

bulkheadCracks in stringer

May cause contamination of ballast water andsmall oil spills

Stringer flange

Stringer webLongitudinal bulkhead

Crack

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16.03.2004Slide 13

4.Transverse

bulkheadCharacteristic damages

1. Stringer toes cracking

2. Bottom longitudinal bracket connection to

transverse bulkhead - cracks

3. Cracking of transverse bulkhead stiffenersconnection to stringers

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16.03.2004Slide 14

4.Transverse

bulkheadCracks in bottom longitudinals

17.

Cracks in toe of transverse bulkhead

bracket ending at bottom longitudinals

(wing tanks, midship area)

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16.03.2004Slide 15

4.Transverse

bulkheadCause - cracks in bottom brackets

Crack in bracket

toe (hot spot)

One sided loading at the transverse bulkheadinduce high local alternating bending stresses at

the bracket toe

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16.03.2004Slide 16

4.Transverse

bulkheadDouble btm at transverse bulkhead

Similarily, one sided alternate loading at the transverse bulkhead also

induces high stresses for a double bottom structure

Critical areas

Modern designs have nolongitudinal girders in

double bottom giving large

relative deflection

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16.03.2004Slide 17

4.Transverse

bulkheadCharacteristic damages

1. Stringer toes cracking

2. Bottom longitudinal bracket connection to

transverse bulkhead - cracks

3. Cracking of transverse bulkhead stiffenersconnection to stringers

Crack in transverse bulkhead

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16.03.2004Slide 18

4.Transverse

bulkhead

Crack in transverse bulkhead

stiffeners connection to stringers

of stringer to transversewith associated brackets

Connectionbulkhead

C f ki i t

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16.03.2004Slide 19

4.Transverse

bulkhead

Cause for cracking in transverse

bulkhead stiffeners

One sided internal loading from cargo and ballast sets up a

shear stress distribution in the bulkhead stiffener

Highly stressed areas are

created around geometrichard points at stiffener

end connections to the

stringer

-may cause ballast water contamination and possible oil spills

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16.03.2004Slide 20

4.Transverse

bulkhead

Questions ?