Educational Adaptation of Cargo Container Design Features

2015 ASEE Zone III Conference

Authors

Christopher M. Moore, Semih G. Yildirim, Stuart W. Baur

Introduction
1. Design criteria
1.1 Foundation
1.2 Structural system
1.3 Infill system
2. Educational adaptation
2.1 Details of design
2.2 Content of the assignment
2.3 Results of the activity
2.4 Survey
3. Conclusion
References
Biographical information


Abstract

Cargo container homes have become increasingly popular around the world in the last 30 years. Because cargo containers are modular in design, they can be used to create efficient, cheap homes. Repurposing cargo containers into homes is a sustainable construction practice due to the majority of the structure coming from recycled materials. Many design parameters of cargo container homes parallel those of standard home construction methodologies (cold formed steel framing/light wood framing) and from a structural standpoint, cargo containers are an effective building material. This paper aims to discuss the design parameters of cargo container home construction and an educational application of the concept. Problem-based learning (PBL) methodology was applied in order to create a discussion group. Building types were handed-out, scaled model and poster presentation were prepared by teams according to defined design parameters. Educational activity is evaluated by survey and critical points are determined to improve.



Introduction

The concept of containerization has developed at great lengths over the past 300 years leading up
to the modern cargo container. An American by the name of Malcom McLean is credited with
the invention and patenting of the cargo shipping container. His success in owning the 5th largest
trucking company in the United Sates (McLean Trucking Co.) allowed him to branch out to
marine transportation. After purchasing the Pan-Atlantic Steamship Company in 1955, he began
experimenting with different shipping methods. It was during his time as owner of the company
that his idea for the modern cargo container came to existence. While it was not necessarily a
new idea, the concept of an intermodal shipping container that could be loaded and unloaded
with ease became very appealing to the U.S. military. Their influence helped to have the cargo
container accepted as the standard for shipping lines all around the world. The cargo container
was issued a patent in 1958 for an “Apparatus for shipping freight.”

The cargo container is known by many names. When used for shipping, it is mainly referred to
as a “shipping container,” but can also be called an “ISO container,” “Conex box,” or “cargo
container.” When used as a construction material, however, it is referred to as an Intermodal
Steel Building Unit (ISBU). Cargo containers are constructed from weathering steel. Weathering
steel includes alloying elements that affect the materials corrosion process. Weathering steel
forms an amorphous inner layer that protects the integrity of the steel. Figure 1 shows the
placement of the layer as well as its composition. The continuity of the layer also adds to the
protection of the steel (1).


Figure 1. Schematic illustration of the corrosion product layers identified on steels exposed to rural and marine atmospheres for the periods of up to five years (1).

Furthermore, weathering steel is an ideal material for cargo containers due to their exposure to
natural elements. Cargo containers spend the majority of their life outdoors on cargo ships, trains
and trucks with little protection from moisture. The cargo container is an appealing construction
material for a variety of reasons. First, their strength and durability provide both structural
support and a long life span. Their weathering steel construction provides not only corrosion
protection, but also strength. Also, with a movement toward sustainable construction practices,
the recycling of unused cargo containers for construction material puts an unused product to use.
Also, the cargo containers modular construction simplifies the design process. Much like bricks
or CMU, cargo containers are designed to specific standards. Table 1 lists the dimensions of the
standard sized containers.

Table 1. Standard cargo container dimensions (2).


Cargo containers also feature corner assemblies that interlock the containers to one another, as
seen in Figure 2. The locking mechanism provides stability when multiple containers are being used in the construction of a building. Cargo containers are designed to be supported from the four corners they sit on, which provides structural foundation advantages.


Figure 2. Illustration of corner locking mechanism (3).

Cargo containers are a useful construction due to their high availability. The cost of shipping
empty cargo containers back to their starting location is higher than the cost of buying a new
cargo container, so many containers are left sitting empty in ports all around the world. In 2012,
according to Drewry Maritime Research, the global container fleet consisted of approximately
32.9 million TEU (Twenty-foot equivalent unit) (4). That figure would estimate 32.9 million
standard 20 foot containers, meaning that there is no shortage of cargo containers in the market
today. Overall, the cargo container should be viewed as a valuable construction material.





1. Design criteria


1.1 Foundation

Cargo container homes require a foundation system just as any other residential dwelling would.
While the design parameters for shipping container homes are constantly evolving due to the
relatively young age of the technology, there seem to be two major methodologies in regards to a
foundation system. Most cargo container homes utilize either a slab-on-grade foundation or a
concrete pile foundation. A basement is possible with either of those two types of foundations,
but because the cargo containers are intermodal containers (and thus can be moved easily) a
basement would not be practical. Moving the containers would leave a large void that would be
wasted. While a basement is possible, the scope of this paper will cover foundation systems for
cargo container homes that do not have a basement.

As applied to cargo container construction, a home utilizing a slab-on-grade foundation system
would lay a foundation and set the cargo containers on top of the foundation. This foundation
system is a very simple methodology for cargo container homes. The modular units are placed on
the floor slab and secured with bolts or fixtures set in the concrete slab itself. The slab-on-grade
foundation system offers a solid platform that will easily support a cargo container home. An
alternative to the slab-on-grade foundation is a deep foundation system. Two common types of
deep foundations are a pile system and drilled pier system. The difference between the two
systems is evident in their construction. A pile is typically a precast concrete cylinder that is
driven into the ground, while a pier is cast on site in a drilled well. Due to having less dead load
of a low-rise housing unit compared to a commercial building such as; shopping mall, mid or
high rise hotel/office building etc., precast pile have a better solution over drilled piers in
consideration of cargo container homes. This foundation system is also referred to as a raised
foundation that is created by using precast piles. The home pictured in Figure 3 is clearly
supported only by precast piles.


Figure 3. Cargo container home using precast pile foundation (5).

1.2 Structural system

The cargo container’s steel construction provides the strength to stack containers upwards of 7
high. That strength, however, is dependent on the entire steel frame/supporting walls intact.
Many cargo container home designs require the removal of entire sidewalls of the container,
which has an obvious effect on the strength and safety of the containers. Giriunas, Sezen and
Dupaix performed a container model analysis using SolidWorks, Hypermesh and Abaqus/CAE
to collect information on the effects of removing steel sections from cargo containers. Their
computer analysis compared 5 different loading scenarios on both unaltered and altered
containers. Their results validated the claim that containers with walls removed yielded before
the required capacity specified in ISO standards. Also, they determined that the roof had little
structural significance, and that the end walls were the strongest load resistive components when
subjected to vertical loads. Their research will hopefully lead to standards and specifications for
the use of cargo containers being used in non-standard applications, following full scale testing (6).


Figure 4. Deformation and prevention for cargo containers (7).

While there is very little literature currently available that discusses the statistical data and
requirements for reinforcing cargo containers for residential use, there are many common
methods that are used to both reinforce and secure the cargo containers in a safe and effective
way. In regards to reinforcing, one concern is that the removal of major walls will cause sag.
Figure 4 depicts both the potential deformation involved with the removal of walls, and a
potential solution to the problem. Steel guardrails can be welded to the interior of the structure to
provide additional support and stability for the container. The amount of reinforcement needed depends
on the amount of material removed, and as previously stated, there are currently no set
guidelines or building codes in regards to this issue. Along with the structural reinforcement, the
connection of the modular units is a concern. Vertical connection is relatively simple, due to the
nature of the container. Every container is designed with a fitting on each corner, originally
intended to secure the containers in organized stacks during shipment. Those same corner
connections prove essential in multi-story cargo container homes and can be used to secure the
modular units together. This methodology is applicable when the containers are oriented in
similar directions, as in Figure 5. Because the cargo containers are constructed from steel,
welding can also be used to secure containers together in a permanent fashion. Securing the
containers to the foundation is often successfully done by welding the containers to steel brackets
cast in the foundation to provide a solid base for the home.


Figure 5. Cargo container home secured with original corner fittings (8).

1.3 Infill system

A cargo container home’s infill system is one of the most functional and aesthetically pleasing
aspects of the building. The infill system consists of the MEP system (Mechanical, Electrical and
Plumbing), as well as aesthetical components. The home’s insulation is also included in the infill
system. In many ways, a cargo container home’s infill system is similar to that of a home build
from a traditional steel or timber framing system. Cargo container homes, however, have many
more spatial limitations, as compared to a normal home or building. The design challenges are
most prevalent in this portion of the design process because while the same families of
components are necessary in a cargo container home, there is much less space to place them.

It has become a very common practice to first construct a non-loadbearing frame around the
inside of the cargo containers. Both cold-formed steel and light timber can be used, and the
framing system parallels that of a standard home. This internal framing offers both a means to
hang drywall or gypsum board as well as a cavity to locate insulation and components of the
MEP systems. Figure 6a depicts the construction of an internal steel framing system to separate
rooms of the cargo container home. Also, voids can be cut into the container and framed in to
allow for standard windows and doors. After the framing is complete, the electrical and
plumbing systems can be installed. Again, the wiring and routing of plumbing is very similar to
that of a standard home, with the exception of spatial requirements. Ventilation/central heating
and cooling is a major challenge due to the height restrictions of the containers. A standard
ventilation system is possible, however, with the usage of shallow ductwork concealed within a
slightly suspended ceiling. Also, radiant heating and cooling systems require less space because
of their use of hoses instead of metal ventilation ducts. The insulation methodology is again,
similar to that of a home constructed by a standard methodology. Both insulating foam and
blown insulation are possible insulation methods, and due to the internal framing, space is
available to do either method. Many cargo container homes have become very successful in
creating a modern, appealing interior design. Figure 6b features the interior of a cargo container
home. The application of drywall, hardwood flooring, standard appliances and furniture, and
lighting creates a home that is very similar to a modern home constructed using a standard
methodology (i.e. without using cargo containers).


Figure 6. (a) Internal framing system for cargo container home (9), (b) Cargo container home interior (10).





2. Educational adaptation


“Materials and Methods of Building Construction” (Curriculum code; ArchE2103) course in
Missouri S&T Architectural Engineering Program covers a variety of educational methodologies
such as; traditional lectures, assigned supplementary reading, documentary movies,
demonstrations (material test, site visit, and brick masonry wall mock-up assembly), discussion
group and hands-on learning experiences. Among these methodologies, a discussion/work group
was created consisting of three or four students working together completing hands-on tasks. The
discussion/lab section of the course was divided into four modules. One of these modules
focused on the implementation of cargo containers as a structural unit for an office space design.
The duration of this study was three weeks with eleven teams.

Cargo containers are of particularly interest as a design platform because of their emerging
popularity worldwide. They are very versatile because of their durability and relatively low cost,
thus make for an interesting subject in showcasing the possibility of modular design.

Problem-based learning (PBL) methodology was applied in this section on cargo container
implementation and in the latter module, which focused on residential home building utilizing
conventional structural systems with variable floor layouts. Prior to introducing the “PBL
blocks”, a series of “preparatory learning blocks” were offered. This allows the students to
become more acquainted with the subject. Preparatory blocks should provide students with
knowledge they can apply in PBL blocks, and the PBL blocks motivate students to explore
further in-depth study (11). The “discussion group” study is also grouped in second module of the
course and it can also be classified as preparatory learning block. In introducing this topic to
students, a short presentation was given providing an overview of this design concept as well as
details into the specification of the cargo containers’ design. Getting a little more specific, this
short presentation included the information regarding materials of construction, standard dimensions,
load capacity, limitations, reason of usage in construction industry and lastly some
built-up samples. This problem is being introduced to the class to be identified, formulated and
solved as a real life problem with architectural engineering practice. One of the challenges of this
assignment is determining the boundary or scope of work. This study, which is rather open
ended, allows for students to purse the idea further with their own research or imagination.

2.1 Details of design

Due to time limitation of three weeks, typical building layouts are handed-out to the students at
the beginning. Therefore, it was not a design studio activity, but an activity for each team to discuss
the subject and make an assessment of requirements mentioned in the rubric. Results of the activity
were submitted as assignments. From the construction of the models, the groups learned the design
features, critical points, construction methods and building envelope of the cargo container. Design
criteria were defined as;

a) An office or retail space with maximum 2 stories
b) Modular cargo container unit dimensions are;
- Unit 1: (l x w x h) (20’ x 8’ x 8’ 6’’) (6.058 m x 2.438m x 2.591m)
- Unit 2: (l x w x h) (40’ x 8’ x 8’ 6’’) (12.192 m x 2.438m x 2.591m)
c) Building types (Figure 7)


Figure 7. Building types.

2.2 Content of the assignment

Each team submitted the results of discussion on;
a. 20’’ x 30’’ foam board as “Poster Presentation” (including text and images). (70% of grading)
b. Scaled model with cardboard (1/50 scale) (30% of grading).
Expectation from the discussion groups and the content of the poster presentation is mentioned in
rubric. In the future, the groups could present their work as an authority on the subject of cargo
container design, which would help encourage group collaboration and further discussion. Scaled
models were assessed as sufficient or insufficient. The minimum requirements for successful
completion of the cargo container design are a complete consideration of all of the design
challenges presented in their poster. The posters were graded as per handed-out rubric. These
items were to be addressed as if the group were to implement a particular solution to this problem
and for addressing the challenges of completing an inhabitable and marketable office space.

2.3 Results of the activity

The grade of the group is reflected by the successful completion of two different tasks, the poster
which has details of the solution for successful design completion and the scaled model of the
building/site made from prescribed materials, which in this case was foam board and corrugated
paper. Samples of poster presentation and scaled models in 1/50 are shown in Figure 8 and 9.
These models were graded on their accuracy, workmanship, and design vision and are a great
method for understanding the 3-dimensional space of each building layout.


Figure 8. Samples of poster presentation


Figure 9. Samples of scaled model in 1/50 scale

2.4 Survey

The results of multiple educational methodologies have been evaluated by survey during the
semester (Table 2). The survey was completed by students two times as before and after the term
project. But, both were after the cargo container design activity and therefore the average of both
survey is being reflected on this paper. There were 36 participant at 1st survey and 25 participants
at 2nd survey. 73 percentage of participants’ academic standing was sophomore and 54
percentage of participants had no construction experience. The rate of significance of this
discussion group as cargo container design activity was 6.12 out of 10 and this rate was the
lowest rate among other similar activities. These activities are compared to find out the critical
points and improve the educational value of cargo container design activity. A partial masonry
wall mock-up has been assembled by each team in a two weeks study. Drawings of the demo
wall and assembly instructions were handed-out the students prior the activity. It was a task that
each steps were clearly defined initially. Therefore, students’ feedback was fairly positive as 8.27
out of 10. Similarly scaled model assembly as term project was a task project having clearly
defined hand-outs (design guide) prior the activity. Whereas, students have to think outside the
box in cargo container design activity. In Table 2 number 1 and 3 activities can be named as the
task projects, but number 2 – cargo container design activity - was a discipline project. This can
be the possible reason of having lowest rate of educational significance. In terms of analogy of a
football game, this means that playing field is specified, some overriding guidelines are given for
the game, but the ball has not been kicked off and thus the group must enter the field and set the
game into play. The freedom on design or studied subject is increased and limitation on PBL is
decreased in discipline project than the task project (12).

Table 2. Average rate of significance of educational activities.


In order to increase the rate of significance of this educational activity, critical points are
determined and some improvements are proposed herein.

a. Link between poster presentation and the scaled model; separated studies were run at
both assignment by teams but, more powerful link shall be maintained between two
assignments.

b. Design flexibility on building types; design flexibility can result in handling more
responsibility and sense of ownership over students instead of handing-out pre-defined
building types.

c. Duration of the activity; the activity lasted 3 weeks as part of the lab and it was not a
term project. It is recommended to do this activity in longer time and/or as a term project.





3. Conclusion


Cargo containers are a valuable modular construction material to be considered when designing a
home. They have the structural capability and design parameters to produce a standard, living
home in a variety of ways. Cargo container homes are both sustainable and cost effective due to
the repurposing of the container itself. Container homes can be designed very similarly to a
standard home, and should be heavily considered in today’s market. Design standards like those
presented in this paper should be standardized in order to create an efficient design process to
produce cargo container homes on a larger magnitude. In order to increase the popularity of this
reusable modular construction units, future architectural engineers shall be promoted and they
have to be competent over basic design features. By using existing design parameters of cargo
containers, a discussion group project has been created as a real life problem. The discipline
project as part of problem-based learning lead the students to think outside the box which was
the main goal of this educational adaptation. Student survey shows that positive feedbacks
received from the students but improvement is necessary to increase the effectiveness of this
activity.

References

1 Revie, R. W., 2011. Uhlig's corrosion handbook. Third Edition, John Wiley & Sons, Inc., pp. 621-631.
Tokyo.
2 Intermodal Container. [Online]. Available: http://en.wikipedia.org/wiki/Intermodal_container. [Accessed
28 April 2015].
3 Campbell-Dollaghan, Kelsey, 2014. The Simplest Metal Mechanism That Changed the Global Economy
Forever. [Online]. Available: http://gizmodo.com/the-simple-metal-mechanism-that-changed-the-globalecon-1530878459.
[Accessed 5 June 2015].
4 W. S. Council, "About the industry," 2015. [Online] Available: http://www.worldshipping.org/about-theindustry/containers/global-container-fleet.
[Accessed 1 April 2015].
5 You can turn a $2000 shipping container into an epic off-grid home, 2014. [Online] Available:
http://www.trueactivist.com/a-shipping-container-costs-about-2000-what-these-15-people-did-with-that-is-beyond-epic/.
[Accessed 16 April 2015].
6 Giriunas, K., Sezen, H., and Dupaix, R. B., 2012. Evaluation, modeling, and analysis of shipping container
building structures. Engineering structures, vol. 43, pp. 48-57.
7 How to build a shipping container home, 2002. [Online]. Available: http://www.residentialshippingcontainerprimer.com/action%20it. [Accessed 16 April 2015].
8 Strether, L., 2015. Home, sweet shipping container, and why not? [Online]. Available: http://www.nakedcapitalism.com/2015/02/home-sweet-shipping-container-not.html. [Accessed 17 April 2015].
9 Hart, K., 2001. Building with shipping containers. [Online]. Available: http://www.greenhomebuilding.com/articles/containers.htm. [Accessed 20 April 2015].
10 Shipping container home interiors. [Online]. Available: http://decoratingbeautifulhomes.blogspot.com/2014/12/cargo-container-home-interiors-shipping.html. [Accessed 20 April 2015].
11 H. K. Banerjee and E. D. Graaff, 1996. Problem-based learning in architecture: problems of integration of technical disciplines. Eurpoean journal of engineering education, vol. 21, no. 2, pp. 185-195.
12 Graaff, E. D., Anette Kolmos, 2003. Characteristics of problem-based learning. Int. J. Engng Ed. Vol. 19, No. 5, pp. 657-662, printed in Great Britain, Tempus publications. [Online] Available http://www.ijee.ie/articles/Vol19-5/IJEE1450.pdf.

Biographical information

Christopher M. Moore, Undergraduate Student, Department of Civil, Architectural and
Environmental Engineering, Missouri University of Science and Technology,
email: cmmnpb@mst.edu
Semih G. Yildirim, Ph.D., (Corresponding Author), Visiting Scholar, Department of Civil,
Architectural and Environmental Engineering, Missouri University of Science and Technology,
email: yildirims@mst.edu
Stuart W. Baur, Ph.D., Associate Professor, Department of Civil, Architectural and
Environmental Engineering, Missouri University of Science and Technology,
email: baur@mst.edu

Download article (pdf) 1.03 MB
Source