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Dolphins

Hamburg-Finkenwerder

Berthing Basin

for Large Vessels

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The Hamburg-Finkenwerder berthing basinfor large vessels

An example of the efficientcombination of flexible steel-pipepiles with rubber cell fenders onberthing dolphins

Over the past few years, the Lower

Elbe and part of the port of Hamburghave been dredged to 14.3 m belownormal sea level. Accordingly, biggervessels can now enter the port ofHamburg from the open North Sea,approx. 100 km distant. Near Finken-werder, right on the doorstep ofHamburg, a berthing basin for largevessels has been built to permit even

large tankers to leave the fairway incases where the envisaged berth isstill occupied or low water preventsfurther progress.

In increasing degree, the port ofHamburg is also being used by vesselsof such draught that they can use theElbe fairway at high tide only. There isa danger of these ships touching thebottom if they are prevented from

reaching their dredged-out berths ingood time. The berthing basin underdiscussion was dredged out to 16.8 mbelow normal sea level (2.5 m deeperthan the Elbe fairway) to provide thesevessels with a suitable berth wherethey can wait for the next high tide.This depth of water is sufficient forempty or partly-laden vessels of up

to 400 000 dwt.

The waiting berth basin is equippedwith three berthing dolphins and fourmooring dolphins. Each berthing dol-phin is designed for the absorptionof 330 Mpm, and equipped with amovable fender panel measuring

6.10 m x 3.70 m for the transmissionof the berthing impact. In addition,bollards are provided for absorbingmax. 200 Mp pull from the springlines.

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Fig. 2: Section of the berthing basin at Hamburg-Finkenwerder

The mooring dolphins take the crosslines and the fore and stern lines.They are designed to accept a hawserpull of 400 and 250 Mp. Slip hooksare provided for holding the hawsers.

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Design work on the berthing dolphinswas based on the following values,which were determined by the respon-sible authority, the Strom- undHafenbau Hamburg (River and PortConstruction Authority of Hamburg):

In the initial stage, efforts were madeto attain the specified values forhawser pull and energy absorptioncapacity using single-pile elastic dol-phins. High-tensile fine-grain structuralsteel St E 70 was envisaged for the

dolphin sections subjected to thehighest stresses. In this context, dueconsideration had to be given to thefact that, for this steel grade, a yieldpoint of 690 N/mm2 (70 kp/mm2) isguaranteed only up to wall thicknessesof 50 mm. The following table showsthe mechanical properties for high-tensile fine-grain structural steels D 53

and St E 70.

Design and constructionof the berthing dolphins

Embedment calculation: Blum methodTop edge of dolphin pile: +5.7m M.S.LCalculat ion level: -18.0 m M.S.L.Impact point: +2.0m M.S.L.Point of action,hawser pull: +6.0m M.S.L.

Coefficient of soilresistance fw: 6.35 Mp/m 3

Specified energyabsorpt ion capacityat +2m M.S.L.: 330 Mpm Specified hawser pullat +6m M.S.L.: 200 Mp Permissible stress: yield point

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Steel grade

D 53

St E 70*

Wall thicknessmm

35

60

50

Tensile strengthN/mm2

(kp/mm2)

630800(6482)

630800(6482)

790940(8095)

Yield pointN/mm2

(kp/mm2)min.

520(53)

510(52)

690(70)

Elongation%

min.

14

1414

12

Mechanical propert ies of high-tensile f ine-grain st ructural steels D 53 and St E 70

* St E 70 is a water-quenched steel

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Design and constructionof the berthing dolphins (continued)

Fig. 5: Comparison of different pipe diameters (heaviest section: 50 mm wall thickness, 70 kp/mm2 yield point)

A review of various pile diameters(Fig. 5) showed that it is possible toattain the specified energy absorptioncapacity of 330 Mpm using a single-pile dolphin with a diameter of about2.2 m, a wall thickness of 50 mm,

of material St E 70. However, thissingle-pile dolphin would have beenrelatively stiff; it would have hada high spring constant of about400 Mp/m. Impermissible pressuresagainst the ships hull could have

been prevented only by using avery big fender panel designed forall-round movement to provide loaddistribution. The pile would haveweighed 85 t.*

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To achieve softer spring reaction,steel-pipe piles with a diameter of1800 mm and having a more resilientcharacteristic (spring constant only290 Mp/m instead of 400 Mp/m) werechosen, and combined with four rub-ber cell fenders in each case. Fig. 6shows the spring characteristic of thiscombination, and the spring charac-teristic of a rigid steel-pipe dolphinwith a diameter of 2200 mm.

As shown in Fig. 6, the four rubbercell fenders make a substantial contri-bution towards the overall energyabsorption capacity of the dolphinonly at an impact load exceeding240 Mp, or more than 60 Mp perfender element. This is explained bythe spring characteristic of the fenderelements employed (Fig. 7). It canclearly be seen that once the limit loadof 71 Mp is exceeded (284 Mp withfour elements) the fender elementscontinue to deform without any addi-tional load being imposed.

* At t his juncture, attention must be drawnto the fact that the spring constant must beviewed together with the depth of water. Inmany cases, the water depth exceeds that inthe Finkenwerder berthing basin under discus-sion. With very great depths of water andcertain soil conditions, pile diameters of 3.0 mand more can be optimum.

Fig. 8: Each longitudinal weld seam is subjec-ted to a stringent ultrasonic test using severalprobes simultaneously

Fig. 9: Submerged-arc welding of a girth weld

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Side view

Top view

Design and constructionof the berthing dolphins (continued)

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For economic reasons, the pileswere assembled from pipe sectionsof various steel grades and withdifferent wall thicknesses (Fig. 14).The overall pile weight was onlyapprox. 63 t.

Various design aspects must begiven consideration when usingrubber cell fenders:

1) Vessels always berth at a certainangle. If several rubber cell fen-ders are used as in this case they are compressed to different

degrees, and thus make differingcontributions towards the energyabsorption capacity of the dol-phin. Also, the energy absorp-tion capacity of the individualelements must be reduced bycorrecting factors for angularloading, as provided by the rub-ber manufacturers in their tables.

Fig. 13 shows in schematic formthe varying degrees of compres-sion of the rubber cell elementsunder angular loading.

2) It is expendient not to transmitthe transverse forces acting onthe fender panel (vertical andparallel to the fender) to thedolphin pile via the rubber cellelements. With the berthingdolphins of the Hamburg-Finken-werder berthing basin, these for-ces must be absorbed by a heavysteel pin arranged between therubber cell elements. This pintransmits the forces into the pile(Fig. 12). The rubber cell fendersare not capable of transmittingthese forces on their own.

Fig. 13: Compression of two rubber cellfenders (Bridgestone system) under

angular loading

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Fig. 15: High-capacity tanker in the Hamburg-Finkenwerder berthing basin

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Notes

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Thyssen Mannesmann Handel GmbH

Hans-Gnther-Sohl-Strasse 1D-40235 Dsseldorf

Postal address:P.O.Box 10 36 51 D-40027 Dsseldorf

Tel.: (* 49 211) 9 67-0

Fax: (* 49 211) 9 67-78 06e-mail: offshore@t-mh.com