Structral Components of Shipping Containers

STRUCTRAL COMPONENTS OF SHIPPING CONTAINERS

Note: On some ISO shelters, some of the primary structural components may be concealed within the wall, roof, and floor panels. The areas where the adjacent panels join will be thoroughly inspected. This inspection will meet the criteria for the Wall Beams and the Roof Beams

Figure 4.1 Shipping Container Primary Structural Components

4.1.1 Corner Fitting. Internationally standard fitting (casting) located at the eight corners of the container structure to provide means of handling, stacking and securing containers. Specifications are defined in ISO 1161. 4.1.2 Corner Post. Vertical structural member located at the four corners of the container and to which the corner fittings are joined. 4.1.3 Door Header. Lateral structural member situated over the door opening and joined to the corner fittings in the door end frame. 4.1.4 Door Sill. Lateral structural member at the bottom of the door opening and joined to the corner fittings in the door end frame. 4.1.5 Rear End Frame. The structural assembly at the rear (door end) of the container consisting of the door sill and header joined at the rear corner fittings to the rear corner posts to form the door opening. 4.1.6 Top End Rail. Lateral structural member situated at the top edge of the front end (opposite the door end) of the container and joined to the corner fittings. 4.1.7 Bottom End Rail. Lateral structural member situated at the bottom edge of the front end (opposite the door end) of the container and joined to the corner fittings. 4.1.8 Front End Frame. The structural assembly at the front end (opposite the door end) of the container consisting of top and bottom end rails joined at the front corner fittings to the front corner posts. 4.1.9 Top Side Rail. Longitudinal structural member situated at the top edge of each side of the container and joined to the corner fittings of the end frames. 4.1.10 Bottom Side Rail. Longitudinal structural member situated at the bottom edge of each side of the container and joined to the corner fittings to form a part of the understructure. 4.1.11 Cross Member. Lateral structural member attached to the bottom side rails that supports the flooring. 4.1.12 Understructure. An assembly consisting of bottom side and end rails, door sill (when applicable), cross members and forklift pockets. 4.1.13 Forklift Pocket. Reinforced tunnel (installed in pairs) situated transversely across the understructure and providing openings in the bottom side rails at ISO prescribed positions to enable either empty capacity or empty and loaded capacity container handling by forklift equipment. 4.1.14 Forklift Pocket Strap. The plate welded to the bottom of each forklift pocket opening or part of bottom siderail. The forklift pocket strap is a component of the forklift pocket. 4.1.15 Gooseneck Tunnel. Recessed area in the forward portion of the understructure to accommodate transport by a gooseneck chassis. This feature is more common in forty foot and longer containers.

Figure 4.2 Exploded axonometric view of a Typical 20' ISO Shipping Container.

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4.2 Walls, Roof, and Floor. Refer to Figure 4.2A

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4.2.1 Fiberglass Reinforced Plywood (FRP). A material constructed of laminates of fiberglass, polyester resins, and plywood, also known as sandwich panel.

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4.2.2 Wall Panel. Corrugated or flat sheet steel, a riveted or bonded aluminum sheet and wall post assembly, FRP, foam and beam, aluminum, or honeycomb material that forms the side wall or end wall.

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4.2.3 Wall Post. Interior or exterior intermediate vertical component to which sheet aluminum or steel is riveted or welded to form a wall panel.

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4.2.4 Wall Beam. Encapsulated vertical component to which sheet aluminum or steel is bonded to form a wall panel.This is found in foam and beam panels.

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4.2.5 Marking Panel. A side wall panel of a corrugated steel configured with a flat portion used for the display of markings and placards. (4.2A)

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4.2.6 Lining. Plywood or other like material attached to the interior side and end wall to protect the walls and/or cargo and facilitate loading operations.

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4.2.7 Lining Shield. A strip of thin metal installed at the bottom of the interior walls to protect the lower portion of the lining from damage by materials handling equipment during loading or unloading operations.

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4.2.8 Kick Plate. A common name for a lining shield installed on the lower portion of the interior front end wall.

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4.2.9 Ventilator. Two or more devices permanently attached to the side or end wall panel that provides openings for the exchange of air (but not water) between the outside and the container interior. (4.2A)

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4.2.10 Roof Panel. Corrugated or flat sheet steel, sheet aluminum, FRP, or foam and beam and aluminum honeycomb panel that forms the top closure of the container. (4.2A,)

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4.2.11 Roof Bow. Lateral non-structural member attached to the top side rails and supporting the underside of the roof panel. Roof bows used with removable cover (tarp) assembly are unattached. Not all container designs require roof bows.

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4.2.12 Roof Beam. Encapsulated horizontal component to which sheet aluminum or steel is bonded to form a roof panel.

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4.2.13 Roof Reinforcement Plate. An additional metal plate on the interior or exterior of the roof panel adjacent to the top corner fittings that provides protection of the roof panel or top rail components from misaligned handling equipment.

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4.2.14 Tarp. Jargon for "tarpaulin" which is a waterproof and flexible fabric used for covering the top of an open-top container. This covering is referred to as a "Tilt" in some countries.

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4.2.15 TIR Cable. Plastic sheathed wire rope that is designed in accordance with TIR customs convention (Refer to paragraph 4.5.6) and is threaded through the welded loops on the sides, end panels and door panels of an open-top container to secure the tarp.

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4.2.16 Flooring. Material that is supported by the cross members and bottom rails to form a load bearing surface for the cargo. The flooring is usually constructed of laminated wood planks, plywood sheets, or other composition material and is screwed or bolted to the cross members. Some containers have welded steel or aluminum flooring, sandwhich panels or a combination of metal and wood. (4.2A)

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4.2.17 Joint Strip. A formed steel or aluminum strip (usually hat-shaped section) installed between joints of the plywood sheet flooring or joints of the plywood sheet lining to help integrate and support the edges of the plywood. (4.2A)

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4.2.18 Threshold plate. Plate forward of the door sill to protect the entrance area of the container floor. This plate is commonly referred to as a crash plate.

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4.2.19 Steps. Folding steps are found on some ISO Shelters and are used to gain access to the roof. They must be folded up prior to transporting shelter.

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4.2.20 Sandwich Panel. A type of fixed or removable panel construction used in ISO Shelters consisting of a thin inner and outer sheet aluminum skin, bonded or fastened to a core constructed of either honeycomb or structural foam and aluminum beams.

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4.2.21 Striker Plate. An additional metal plate on the exterior of the roof panel adjacent to the top corner fittings that provides protection to the roof panel or top rail components from misaligned handling equipment.

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4.2.22 Sling Pad. An additional metal plate on the exterior of the roof panel located in the center of the roof panel that provides protection to the panel from lowered handling equipment.

Typical Container Connection at End-wall Plan Detail

Typical Container Connection Plan Detail

Typical Container Termination Plan Detail

Typical Exterior Container Back Wall

Typical Container Floor Section Detail

\

T ypical Exterior Container Wall

Typical Interior Container Wall

Typical Roof Section Detail

Shipping Container Home Floor Plan Examples.

One Bedroom, One Bath Shipping Container Home Floor Plan Total Square Footage: 320 sf

One 40' Shipping Container



One Bedroom, One Bath Shipping Container Home Floor Plan

Total Square Footage: 320 sf


Commercial Office Container Floor Plan Total Square Footage: 640 sf

Two 40' Shipping Containers

Selection of one, two, and three Bedroom Shipping Container Home Floor Plans Total Square Footage: 160 - 320 sf

One and Two 40' Shipping Containers

Five Bedroom, Three Bath Shipping Container Home Floor Plan Total Square Footage: 1600 sf

Five 40' Shipping Container

Two Bedroom, One Bath Shipping Container Home Floor Plan Total Square Footage: 640 sf

Two 40' Shipping Container



Three Bedroom, One Bath Shipping Container Home Floor Plan Total Square Footage: 640 sf


Two Bedroom, Two Bath Shipping Container Home Floor Plan Total Square Footage: 640 sf



Two 40' Shipping Containers + 4'x40' fill conventional construction fill


One 40' Shipping Containers + 2'x40' fill conventional construction fill

General Comments on ISO Shipping Container's Inherent Capacity to Satisfy Building Code Requirements in Shipping Container House Applications:

ISO shipping cargo containers are tested in accordance with the requirements of International Standard ISO 1496/1 which stipulates static and dynamic design load factors to be complied with. In the case of a 20' steel container, it is designed to have a maximum gross weight of 52,910 lbs (typically has a tare weight of around 5,000 lbs and a payload (P) potential of 47,910 lbs). The container when loaded to its maximum gross weight must be capable of withstanding imposed loads of 2g downwards, 0.6g lateral and 2g longitudinal plus be able to withstand eight similar containers loaded to maximum gross weight stacked on top of it in a ships hold or at a land terminal. It therefore has a very sever operational life and, notwithstanding its low tare weight it is very strongly built.

The side walls and end walls/doors have to withstand loadings of 0.6P and 0.4P respectively, these values equate to 28,746 lbs and 19,164 lbs based upon the payload given above. The side wall area in contact with the load is 146.56 sq. ft. giving a pressure of 196 lbs/sq. ft. Corresponding figures for the end wall/doors are 51.78 sq. ft. and 370 lbs/sq. ft. These figures are well in excess of the 20 lbs/sq. ft.

wind load required for structures less than 50 ft. high. A wind of 100 MPH produces a pressure of only 30 lbs/sq. ft.

The roof load test is 660 lbs over an area of 2' x 1' applied to the weakest part of the roof. The load is usually applied at the center of the containers positioned with the 2' dimension aligned longitudinally. Thus the roof is able to support an imposed load of a minimum of 330 lbs/sq. ft. The design is easily capable of supporting the basic snow loads of 30 lbs per sq. ft. evenly distributed.

It is difficult to quantify uplift and suction forces. Unlike a building, the roof of a container is an integral part of the structure; it is continuously welded around its entire periphery and is itself made from sheets of corrugated 14 ga. Cor-Ten steel also continuously welded together. This steel, also used for the side and end walls has a minimum yield strength of 50 ksi, and tensile of 70 ksi. The probability of the roof being removed by these forces is practically zero as the entire container structure would have to be destroyed for this to happen.

However, it is not unusual for the complete container to be lifted or blown over if it is not secured to the ground in storm or hurricane conditions. This would be prevented by adequate foundation design which is the responsibility of the customer. As you know when containers do blow over in container yards the resulting damage is almost always minimal, another testimonial to their strength.

The floor is design to pass a concentrated load test of 16,000 lbs over a foot print of 44 sq. inches. The floor has also been designed to pass a test at twice its rated payload capacity of 47,895 for a 20 container and 58,823 lbs for a 40' container when evenly distributed.

The boxes are suitable for earthquake areas of seismic rating of up to the California standards.

History of ISO Shipping Containers The shipping container has only been around for the last 50 years. The advent of this method of modular standard containerization of goods revolutionized the transportation of goods and ultimately the international export market as turnaround time, theft, damage to goods and costs all went down. Until 1956 goods packed in bales, sacks or barrels were individually transferred from the vehicle to the waiting cargo ship. This was manual work carried out by “longshoremen” using pulleys,

cargo hooks and a significant labor force. An average ship had 200, 000 individual pieces of cargo and it would take around a week to load and unload.

History credits Malcolm McLean with the development of the shipping container. By the 1950‟s McLean had developed a large haulage business on the East Coast of the USA but had never forgotten the days of being a driver waiting for a whole day for goods to be loaded and unloaded at the port of New Jersey. He patented a container with reinforced corner posts that could be craned off a truck chassis and had integral strength for stacking. McLean was so confident in the potential of this modular cargo he took a loan for $42m and purchased the Pan-Atlantic Steamship Company with docking rights so that he could modify cargo ships to use his new containers. He was forced to choose between haulage and shipping by the Interstate Commerce Act and so he focused on redeveloping the shipping firm and renamed it Sea-Land. In April 1956 the modified oil tanker owned by Sea-Land „Ideal X‟ sailed from New Jersey to Houston carrying 58 of the new containers. Meanwhile on the West Coast of the USA the Matson Navigation Company decided to while McLean used

invest in container technology. They took a different view and 33 foot long containers, since these were the limited length permitted for a truck

chassis the Matson company chose 24 foot. They were importing tinned goods from Hawaii and considered weight to be an issue, thus choosing a smaller container. In 1958 the first Matson container ship set sail from San Francisco. Since there were specific docking requirements, namely large cranes, containerization required investment. The New York Harbour Authority realized this need and the potential of containerization and so built the first container port 'Port Elizabeth' in New Jersey in 1962. The Port of Oakland in California also realized that containerization would revolutionize trade with Asia and would protect the declining industry and so invested $600k in new facilities in 1969. The advent of containerization had hit the longshoremen hard. In 1960 a new agreement was reached between the dockside unions and shipping companies where the companies could bring in new machinery but a large pension fund was set up for longshoremen and they were given reduced working hours. Thismodularization of cargo reduced the time required to load and unload, it also reduced the number of longshoremen required, which resulted in the strike of 1971-72. Longshore jobs were allocated on a rota basis by the unions but containerization saw the needs for specialist crane operators thus the ports wanted to hire staff on a permanent contract. The shipping owners won their rights to employ the specialist staff and the containerization of shipping continued to move forward .

The next step was to standardize the containers. At the time Matson‟s on the west coast were using 24 foot containers and Sea-Land on the east were using 35 foot containers. The military were interested in containers but in a time of war the varied sizes would not be efficient. The Government was therefore pushing for standardization as were the freight companies who wanted to invest in containerization. McLean owned the patent on the corner posts that were so vital to the strength and stacking of the containers and it was his release of this patent that allowed the ISO standardization to take place . In 1969 Richard F Gibney, working at Shipbuilding and Shipping Record in the UK, simplified the statistics involved with comparing differing container sizes he coined the phrase Twenty Foot Equivalent (

TEU) and this is the term that is still used to describe containers.

What are ISO shipping containers made from? A typical ISO shipping container is made from a „weathering steel‟ as specified within BS EN 100255:2004. This is commonly known as „Cor-ten‟ steel. Cor-tensteel is a corrosion resistant steel that is used within many industries where exposed steel sections are necessary, e.g. building panels, facades and sculptures. „Weathering steels are specified in BS EN 10 155:1993 (superseded by BS EN 10025-5:2004) and within this category Cor-ten is a well known proprietary grade. These steels have properties comparable with those of Grade S355 steels to BS EN 10 025‟.

What are the characteristics of an ISO shipping container? Shipping Container Specifications for the most common ISO Standard Shipping Containers:

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External of a stand. ISO shipping container: 8' wide (2.44m) x 8' 6". (2.6m.) high, and the usual lengths are 20' (6.1 m) and 40' (12.2 m).

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Internal of a stand. ISO shipping container: 7' 10" (2.353 m) wide, 7' 8.625" (2.388 m) high, and 19' 4.25" (5.899 m) or 39' 5.375" (12.024 m) long. Characteristics and Components of a standard ISO shipping container: 1. Monocoque body

2. Corner Castings 3. Steel corrugated sheet sidewalls, roof, and back panel 4. All-welded-steel, continuously 5. Purin reinforced Plywood Floors 6. Forklift pockets 7. Grappler pockets 8. Gooseneck tunnel ISO Standard 40' Low Cube Shipping Container Drawing Formatted: Font: (Default) Verdana, 9 pt, Font color: Black

The shipping container floors are made of planking or plywood wood, which is very strong and resilient, does not dent, and may be easily replaced during repairs. The floors also have a strong friction surface, which is important for cargo securing. Most containers are sprayed for insects because when lumber is used, it must comply with the quarantine regulations in most countries. The forklift pockets of standard ISO steel shipping containers are easily visible and allow handling of empty shipping containers with forklift trucks. Forklift pockets are installed only in 20' x 8‟ x 8‟ standard ISO steel shipping containers and are arranged parallel to the center of the container in the

bottom side rails. The 40' standard ISO steel shipping containers do not have forklift pockets. This is due to the fact that the location of the pockets are relatively close together and such large containers would be difficult to balance. Gooseneck tunnel of standard ISO steel shipping containers: Many 40' containers have a recess in the floor at the front end which serves to center the containers on so-called gooseneck chassis. Grappler pockets of standard ISO steel shipping containers: Most all shipping containers are handled by top spreaders using what‟s called corner fittings or corner castings. Also, some containers have grappler pockets. These were originally installed for hanging garments. Additional specifications on steel shipping container: 1. Racking/Shear Load of the shipping container (corner posts) 16,000 lb 2. Side Wall Lateral Load of the shipping container 235 psf 3. End Wall Lateral Load of the shipping container 366psf 4. Racking/Shear Load of the shipping container 33,500 lb 5. Stacking/ Axil Load of the shipping container 210,000 lb 6. Roof Load of the shipping container 300psf 7. Floor Load of the shipping container 100 psf

Using Pier Footings for Your Shipping Container Home by Terry

Caveat: before you read the main part of this post, please note that this would be my approach to things. That means what you are about to read is all opinion from personal experience. I get a lot of visitors who are owner-builder types like me, so I figured I would create this post to help some of you out there. You can do things the way you wish and use your own approach; so please don’t contact me with issues or problems or accidents resulting from your own incompetence, lack of knowledge or skill level, or equipment failure. I don’t want you to hurt or kill yourself, so be smart! You can easily create a situation where you can get seriously injured or die when working with things as heavy as shipping containers. Just use common sense and safe building practices… and if you are not sure of yourself, just hire a professional, they are everywhere. Use this information at your own risk and responsibility. OK, with that said… If you are an owner-builder, you have a few options when it comes to a foundation: concrete slab on grade, crawlspace, full basement, or pier footings. My favorite? Definitely, the pier footings. I am speaking from the standpoint of the do-it-yourself perspective and cost. The pier foundation requires less concrete, less digging and doesn’t take a lot of tools and equipment to get the job done. Having the same benefits as the basement and crawlspace foundations, the pier footings gives you the freedom to get under the container for modifications and repairs. One thing to keep in mind is that you don’t want any moisture underneath the container home, so you have to seal the bottom and insulate it as well. Placing the home directly on dirt or on a slab could facilitate corrosion. Moisture is the enemy of container homes. Seal, coat and avoid moisture where possible.

So how to make those big, deep holes in the ground? You don’t want to use a shovel–that’s too much work and isn’t as precise. You really want to get your hands on an auger. Preferably a two-man gaspowered auger. If you are capable of getting a hold of heavy machinery, then go for that–but its rather expensive to rent and I hope you don’t screw something up on it or you will be responsible for some costly repairs. After you get the holes bored out of the earth, you will want to employ some forms (huge preform tubes or made from pieces of plywood) in order to precisely pour the proper amount of concrete. As for rebar (reinforcing bar), you definitely want to get those into the forms before you pour the cement in order to reinforce the concrete and add greater load-bearing strength. You will need some heavy gauge flat metal plates (at least 1/4″ thick) to set into the cement, letting the concrete cure solidly around the base of the plates; leaving the top part of the plate uncovered and exposed to air. You will be setting the container corner directly on top of the plate, so keep it flush and level. The underside of the plates will need some arms or support bars welded to them. In the past, while working on some pier footings for some outside structures, I had cut some 1/2 inch rebar about a foot long and welded four of them to the underside of some 8×8 plates–this worked beautifully. Note: with any foundation job, one of the biggest “oops” moments could result from not keeping each footing level with one other because you rushed or just didn’t think about that facet of your build. Talk about a goof that is hard to fix properly! There are methods and instruments to ensure you have a level foundation, just Google them and please use them. You don’t want a crooked platform for your container home. The image below shows one technique with a string run across a series of footings. Another thing, if you are working with an inspector because you are in one of those jurisdictions, you can’t get ahead of yourself. Be sure you let them see every stage of what you are doing so that they can approve it for the next stage of your construction. After your footings have cured properly, the main load-bearing corners of the container(s) sit on top of the plates and are then welded in place. Don’t weld the container(s) to the plates until you are positive you have things positioned right! Grinding off welds is a bitch if you have never done it–it sucks. If the footings, even after you took the time to get things right, happen to not be level, you can possibly weld additional plates to the embedded plates to create more elevation BEFORE you set the container(s) on top. You can check for level several times before setting the container(s) to ensure you haven’t goofed up. OK, that’s about it. Be careful and stay alert!

pier forms from plywood

footing tube with rebar inside

Shipping Container Foundations: Part 2, Concrete Footings

Submitted by container-trader on Mon, 10/31/2011 - 08:45 shipping container foundation

Concrete footing are another option for the foundation for your used shipping container. Building concrete footings are more complex and involved than the wooden beam option, but if you're planning on keeping your container in one place for a long period of time it may be worth the investment.

Materials Needed:

Premix Concrete - total amount depends on your geographic area Loose stone or gravel 1/4" plywood to construct the form 2"x2" or similar wood planks to construct the form Using concrete footings as a foundation for your shipping or storage container falls in the middle cost range of the three options. It's cost effective, durable, but requires more time and attention when building the container foundation.

Before you being to build the concrete footing foundation for your container, you need to decide how deep the footing must be. If you live in an area with no frost this decision may not be necessary. However, if your area is prone to frost the freezing of the ground can shift your foundation and cause problems later on. The only way to prevent "frost heave" is to build your footing at least 6" below the frost line. The frost line is the maximum depth where the ground will freeze in the winter and this depth varies from 50" in North Dakota, to 0" in Florida. To learn more about the frost line in your area you can refer to the National Snow and Ice Data Center.

The second step is to decide how large your footings must be. As a general rule, one or two stacked 40' ISO containers will require 10" deep, x 20" wide, by x 20" wide (not included the extended frost footing). The chart below offers suggestions on how large your footings should be.

Footing Size

Cubic Feet

Cubic Yards

80lbs bags

8" x 16" x 16"

1.2

.044

2 bags per footing

10" X 20" X 20" 2.3

.086

3.8 bags per footing

12" X 24" X 24" 4

.15

6.75 bags per footing

The third step is to mark off the area that the storage container will take up. Measure the area out, making sure that all corners are square so that your footings are in the correct place. It's a good idea to post the area with stakes, and then tie them off so you have a strong visual idea of the size and space required.

Decide which is the highest of the four corners and begin the process here. Dig out an area wider and slightly deeper than required by the footing and compact the soil in the bottom. Follow this up by adding a 3" base of loose stone. Using the plywood and planks, construct a concrete form to the dimensions decided earlier. If you're going to reuse the same form for each footing it's better to assemble the form with screws so that it's easier to take it apart and reassemble it for each footing. Lining up the footings properly is key to this project, and the first footing will be the point from which the others are built. It's also advised to add rebar to increase the strength of your footings and prevent them from cracking. Rebar should be cut 8" longer than the depth of the hole, and driven into the ground so they are flush with the top of the footing form. The rebar should be a few inches apart in each footing, and the amount of rebar depends on the size of your footing.

Once the form is placed in the hole and the concrete poured, allow it to set for 48 hours before removing the form.

The next footing must be measured and placed based on the height of the first one. To do this accurately you'll need a laser level with which to measure the height. With the proper height and distance lined up, you're ready to pour your final three footers or more if you require the added security. Repeat the same process of digging the area out and installing the stone and concrete form, and pouring the concrete until all footers are in place.

Ideally, this should be complete several weeks before the container is due to arrive. The actual time may vary depending on the heat and humidity in your area, and it's best to ask a professional the appropriate time to allow the concrete to cure

Structral Components of Shipping Containers

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