Container Ships

2012 Container Ship

Diego Cerezo San Frutos Andrés Serena Gómez

Container Ship 2012 Table of contents Introduction .................................................................................................................................. 3 Definition....................................................................................................................................... 4 Classification of container ships .................................................................................................... 4 •

Box ship. ........................................................................................................................ 4

•

"RORO" Roll-On/Roll-Off ............................................................................................... 5

•

"LOLO" Lift-On/Lift-Off .................................................................................................. 5

Loads suffered by the cargo .......................................................................................................... 6 •

Static loads .................................................................................................................... 6

•

Dynamic loads. .............................................................................................................. 6

•

Yawing loads .................................................................................................................. 6

•

Vertical oscillations ....................................................................................................... 6

•

Linear movements beyond longitudinal and transversal axes...................................... 7

•

Lateral movements ....................................................................................................... 7

•

Pitching .......................................................................................................................... 7

Structural Analysis of Container Ships .......................................................................................... 8 1.

Hull girder strength including torsion strength ............................................................. 8

2.

Local strength plating and ordinary stiffeners .............................................................. 9

3.

Transverse primary members, stringers, floors, girders ............................................... 9

4.

Structural continuity ..................................................................................................... 9

5.

Fatigue ........................................................................................................................... 9

How to load containers ships ........................................................................................................ 9 Discussion about the future trends and development for container ships……………………………10

References ...................................................................................................................... 11


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Container Ship 2012 Introduction Container ships are one of the biggest family ships. The bigger container ships can go to more than 350 meters length and with a capacity of more than 14000 containers, although this growth has not ended yet, being published some studies of container ships of 18000 units. This spectacular growth will not have been possible without the development of powerful engines that allow this ship to reach 23 knots, 90000 horses of power and a diary fuel consume of 250 tons. In this brief overview through this family of ships we tried to expose in a visual but at the same time accurate manner the main fields that cover the characteristics but also technical part.


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Container Ship 2012 Definition Container ships are the ones in charge of transporting standardized containers and they are used to transport any kind of cargo all over the world. The standard containers are part of the "Intermodal freight transport" which allows transporting in an easy, fast and efficiency way the freight between the different modes (ships, trains or trucks) without any handling of the cargo itself when changing modes. The 95% of the standardized containers are from 20 or 40 feet long. The dimension of the ships depends on the number of containers that it is supposed to carry with. The measurement unit for transport capacity used is TEU (Twenty feet Equivalent Unit), that is a 20 feet container is equivalent to 1 TEU and a 40 feet container is equivalent to 2 TEU. The height and width of the containers are also standardized but exists different measurements.

Classification of container ships The classification of container ships can be made based on the following points: 1. Developing generations: based on capacity, determined by the number of TEU 2. Handing modes: Box ships, LOLO and RORO. 3. Ship generation: Panamax, Post-Panamax, Suezmax, Post-Suezmax, Post Malacamax. 4. Level of specializing: general cargo, semicontainer, purpose-built, container ship. 5. Service range: feeder ships, mother ships. In terms of type of cargo operations it can be found three mainly types

Type •

Picture

Box ship: most common type of container ship, the containers are loaded from the outside with special cranes.


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Container Ship 2012 •

"RORO" Roll-On/Roll-Off: containers are displaced into the ship with adequate vehicles, after the displacement they are driven off

•

"LOLO" Lift-On/Lift-Off: the containers are firstly placed on a barge or other cargo ship and by a lift or crane displaced to the container ship

Other classification is found with respect to different developing generation ships

Name

TEU

Length (m) Beam (m) Draft (m)

Ultra large container vessel

14,501

366

49

15,2

New panamax

10-14,5

366

49

15,2

Post panamax

5,10110,0

366

49

15,5

Panamax

3,001-5,1

294,13

32,31

12,04

Feedermax

2,001-3,0


Picture

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Container Ship 2012 Name

TEU

Feeder

1,001-2,0

Small feeder

Up to 1,0

Length (m) Beam (m) Draft (m)

Picture

Loads suffered by the cargo Two mainly types of loads conditions can be found: •

Static loads: mainly caused by the pressure due to the pile up of the containers that can make the cargo brake. This pressure will depend on the dimension, weight, size and number of units piled up.

•

Dynamic loads: produced in the load and unload, during the transportation and manipulation of the containers. These loads can produce accelerations, vibrations and shaking due to the movement of the water. In the next table are shown the different dynamic loads that can affect the container ship itself and the cargo.

Type of load •

Figure

Yawing loads: rotation of the ship around its vertical axe. It occurs due to the impossibility of the ship to have a straight direction.

•

Vertical oscillations: upper and lower accelerations on the ship beyond its vertical axe. Only with calmed sea exists balance on this load. These oscillations affect the containers and its cargo. This can produce the elevation or the sink of the ship due to the movement of the sea.


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Container Ship 2012 Type of load •

Figure

Linear movements beyond longitudinal and transversal axes: the ship is accelerated or decelerated to prow and stern, and from one band to another. These loads can produce important torsion loads.

•

Lateral

movements: movement of the ship around its longitudinal axe. Can produce angles from the horizontal normally from 10º to 30º but can raise to 45º. 10º

•

30º

45º

Pitching: movements of the ship around its transversal axe. In this movement the ship is picked up from the prow and picked down from the stern and vice versa.

The total loads suffered by a container ship can be summed up with this figure:

Figure 1. Total loads suffered by a container ship


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Container Ship 2012 Structural Analysis of Container Ships Container ships have a specific architecture, they have an enormous deck to carry the containers and sometimes are provided by cranes. All of these are built around a strong keel in order to get the stability of the ship. On the other hand the hull of container ships is different depending on if they will be used in frozen water or not. All of these components are made of steel plates and stiffened plates due to the excellent behaviour of this material subjected to variable distributed loads (cargo, selfweight, water loads and wave loads). The vessel is assumed to be a simple rigid and flexible beam in which the waves of the sea act and create stresses that produce bending of the vessel, this is known as hogging and sagging (see figure 2).

Figure 2. Hogging and Sagging In order to study the strength of the vessel, it is necessary to distinguish different loads situation and the behaviour of specific parts of the vessel. The study must be done focusing on these parts: 1. Hull girder strength including torsion strength: The check is done in order to know the hull girder bending stress, shear stress and warping stress. Figure 3 shows the deformation and hull girder stress of a large container ship.

Figure 3. Deformation and hull girder stress. Diego Cerezo San Frutos Andrés Serena Gómez

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Container Ship 2012

2. Local strength plating and ordinary stiffeners: The results of this study are: thickness of plating, shear area and section modulus of stiffeners, dimensions and scantlings of brackets, buckling. 3. Transverse primary members, stringers, floors, girders: The aim is check yielding and buckling. 4. Structural continuity: Is useful to provide information to make possible modifications of connections design. 5. Fatigue: Allows knowing the damage ratio or fatigue life of connections. One of the most important parts is the behaviour against fatigue of the vessel due to water and wave loads. These are every moment changing so the ship is continuously subjected to variable loads. That is, a huge number of cycles load. So the weld design of the plates must avoid fatigue failure; otherwise the integrity of the ship structure could be in danger. The assessment must be done in the following details: • Hatch corners. • Connection of side longitudinal stiffeners with stiffeners of transverse primary supporting members.

How to load containers ships Nowadays there is a very wide span of containers types and methods to load the vessel, the next rules must be taken into account at the loading moment due to get the stability of the ship and the safety at this moment: • • • • • • •

Looking for cracks or holes on the container. Verify the weight of each container. Lift the container with a crane. Raise the container from the dock and place it into the cargo hold of the container ship Place the heaviest containers at the bottom in order to prevent unbalanced. Place the containers along the width and length of the cargo hold in order to prevent unbalanced. Align the support point on the top and bottom of each container Verify that the securing equipment is adequate and attached correctly to each container.


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Container Ship 2012 Discussion about the future trends and development for container ships Despite the changing production and world trade, the maritime transport has continually grown for the last decades. This growth has been suffered specially by container ships. The use of containers growth is shown by the nowadays construction of bigger ships, reaching some of them 16000 TEUs. This advance is directly related to the growth of the developing countries, especially in Asia and South America and the tendency to globalization of the multinational manufacturing companies with at the same time improvement of the marine structures, giving the possibility and necessity of the construction of bigger container ships. The international structural commercial changes and the evolution of the marine transport directly affect the development and expansion of harbours. Therefore, it is essential to analyse these aspects and its recent characteristics, because they show the reference beyond which the development of the harbours are being done. This changes are hardly being affected by the development of the containers transports, changing this the appearance and construction of harbours. This huge development of the container transport has to be done by the hand of a security in the transport and manipulation. This issue is bigger as long as the ships have a higher transport capability, so the control and resistance tests should be done with the greater precision as possible. Therefore, the commercial opportunities that the containers transport gives are a really big challenge to the marine structural engineers. The future of container ship development is promising.


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Container Ship 2012 References Webpages http://forshipbuilding.com/ship-types/container-ship/ http://www.container-transportation.com/container-ships.html http://plus.upc.es/gemt/Docs/2003/contenedores.pdf http://www.ehow.com/how_8133351_load-container-ship.html http://ocw.unican.es/ensenanzas-tecnicas/transportes-maritimos-especiales-yestiba/material-de-clase-2/416_Tema16_TE.pdf http://www.math.chalmers.se/Math/Research/Preprints/2009/22.pdf http://www.veristar.com/content/static/veristarinfo/images/4706.12.532NI_2008_11.p df http://www.ehow.com/about_5044496_types-container-ships.html Figures •

Cover:

http://1.bp.blogspot.com/-hjLb2zTKsSA/TpLKCrIBFWI/AAAAAAAAGCE/YOMBlLLMs4/s320/barco_container_retocado.jpg •

Types of loads:

http://ocw.unican.es/ensenanzas-tecnicas/transportes-maritimos-especiales-yestiba/material-de-clase-2/416_Tema16_TE.pdf •

Classification of container ships:

Box ship: http://flotilla19.d11nr.info/Images/BayPatrol/Loading.jpg RORO: http://www.arabnews.com/sites/default/files/imagecache/galleryformatter_slide/Cont ainer-vessel_0.jpg LOLO: http://www.workboatsinternational.com/images/STLS1412.jpg Panamax: http://img.nauticexpo.es/images_ne/photo-g/buque-de-carga-buqueportacontenedor-panamax-astillero-naval-31084-376325.jpg

New panama: http://seeker401.files.wordpress.com/2010/07/panamax20ice20412201600x.jpg Ultra large container vessel: http://marineinsight.com/wpcontent/uploads/2011/03/ultra-large-container-ship.jpg Post panama: http://www.capital.com.pa/wp-content/uploads/2011/05/page34.jpg Federmax: http://www.uktrainsim.com/filelib-info.php?form_fileid=26643 Feeder: http://ports.co.za/news/article_2009_08_26_4300.html Small feeder: http://www.ibiblio.org/maritime/Newspaper/thumbnails.php?album=12842 Diego Cerezo San Frutos Andrés Serena Gómez

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Container Ships

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