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Buildable Bridge Models BRIAN BRENNER, BRIAN GRAVEL, and JULIA CARROLL Tufts University, Department of Civil and Environmental Engineering, Medford, MA 02155, USA. E-mail: [email protected]

ABSTRACT

This article describes a project to design and fabricate buildable bridge models of different structural types. The models, constructed out of wood, alumninum and string, are designed to be easily transported to classrooms. The models are available for use in engineering outreach for grades K-12. The working models demonstrate different types of bridge design, architecture, and construction methods. The models are assembled piece by piece by grade school students in a way that simulates and illustrates the actual construction process.

In a classroom presentation, engineers and/or engineering students present a short slide show which describes different bridge types, various roles of civil engineers and an overview of engineering in general. Following this presentation, students build the bridge models with help from the presenting engineers. For example, in construction of the cable-stayed bridge models, students first place the two pylons on the model baseboard, and then sequentially place segments and cables for deck pieces, illustrating the cantilever method.

The models are useful for demonstration of basic engineering concepts such as flow of force, and tension and compression. By building the bridges, young students are

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introduced to the idea of construction staging, in that bridges don’t just appear in their final state, but have to be planned for construction one step at a time. The process of building each model matches young students’ natural curiosity with block play to basic engineering concepts. In addition, having engineers in the classroom enlightens the students to new career options and a greater understanding of the built environment and how it is formed.

INTRODUCTION

Tufts University has developed a program to create buildable bridge models of different structural types. The models are available for use in engineering outreach in grades K-12. The working models demonstrate different types of bridge design, architecture, and construction methods. The models are assembled piece by piece by grade school students in a way that simulates the actual construction process.

Figure 1 Model of a suspension bridge. Engineers and/or engineering students bring the bridge models into the

classroom to give a short presentation which describes different bridge types and an overview of engineering in general. Following the

presentation, students build the bridge models, with help from the presenting engineers or students. For the model of the cable stayed Zakim Bridge in Boston, Massachusetts, the spans are constructed piece by piece from the pylons, demonstrating the balanced cantilever method (Figure 2). The models are useful for demonstration of basic engineering concepts such as flow of force, and tension and compression. By building the bridges, young students are introduced to the idea of construction staging, in that bridges don’t just appear in their final form, but have to be planned for construction one step at a time. The process of building the models matches young students’ natural curiosity with block play to basic engineering concepts.

This article includes discussion of the literature on the subject of block play, as well as the approach, details, applications, and future phases of the project.

LITERATURE REVIEW

Many budding young engineers receive their first engineering experiences playing with blocks. Block play has been recognized as a valuable and effective way to introduce children to engineering concepts, to inspire creativity, and to simulate engineering processes such as iterative design.

Hirsch [1] describes block play in relation to mathematics and science. The anthology includes a compilation of articles about the benefits of block play with an article by Mary W. Moffitt about what and how children learn about science by playing with blocks. These lessons include systems, interaction of forces, and structural stress. Another article in the book by Kristina Leeb Lundberg explains what and how math concepts are learned through playing with blocks. These concepts

Figure 2: Staged Construction

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include: geometry, topology, seriation, reversibility, and iteration. Cuffaro [2] contains examples of how children respond to block play

with real observation and dialogue. Through this one can “see” how block play teaches math and science lessons. The article also contains a list of learning stages which children experience when building with blocks, such as going from carrying blocks, to making rows, to making bridges, etc.

Phelps and Stannard [3] contains information on how children learn through constructive block play and a discussion of how this experience leads to increased mathematical ability later in life. The article promotes playing blocks as an educational toy.

Lefebvre [4] contains information on how parents can teach children lessons while playing with blocks. It contains information on what children can learn through playing with them, such as creativity and problem solving skills.

Chalufer, Hoisington, Moriarty, Winokur, and Worth [5] contains a discussion of a Head Start study on children in a classroom playing with blocks. The article encourages use of blocks in classroom as an educational tool, and discusses their relationship to the content and process criteria of the National Science Education Standards (NRC 1996) and the National Association of Teachers of Mathematics Principles and Standards for School Mathematics (NCTM 2000).

Ansel [6] contains information on what children learn while playing blocks. The article describes what is learned in architecture, math, and language. It also contains information about the history of blocks. In the aggregate, the literature describes block play as an effective approach for teaching and learning basic science and engineering concepts. The articles largely deal with free from block play. The Tufts University Buildable Bridge project comprises a subset of this approach, in which working models are pre-designed by college students for presentation and construction by the grade school studentsfor demonstration of specific contents. The approach is described in the next section.

PROJECT APPROACH

Buildable bridge models are designed and constructed by Tufts University undergraduate and graduate engineering students. To date, seven models have been constructed:

Zakim cable stayed bridge Double arch bridge Suspension Bridge Bascule Bridge Double swing span bridge Vertical lift bridge Tacoma Narrows Bridge

An eighth model is under design by a group of senior engineering students. This model will illustrate design and construction issues associated with post-tensioned concrete box beam bridges. The models are designed and detailed in AutoCAD (Figure 3) and constructed of pieces easily handled by grade school students. Each model has a wood baseboard measuring from 5 to 6 feet in length. The models are designed to be easily transported and assembled.

Figure 3: Suspension Bridge Tower AutoCAD Model

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University students have developed a short Powerpoint presentation for use during a model building session, as well as presentation guides for the grade school classroom that describes bridge engineering in general and different features of the bridge models. The project web site (http://www.ceeo.tufts.edu/etc/bridge/), contains descriptions of models, CAD plans, presentations, and other information to assist in classroom presentations.

A class room presentation lasts between 45 to 60 minutes. The presentation is made by a senior engineer or educator and one or more engineering students. The overview presentation given by the engineering students is intended to engage the grade school students’ interests in the variety of bridge types and the role engineers play in creating them. Engineers make an attempt to connect the topic to the students’ own lives by asking about bridges with which they are familiar. Next, a bridge model is built sequentially by the grade school students. Starting with the baseboard, students construct towers, starter segments, and then build the bridge model piece by piece, assisted by the university students. The senior engineer/educator will call for volunteers from the class, with assistance from the classroom teacher. During the construction, presenters talk about different aspects of the bridge design and construction, for example:

Why are the tower built first and not last? What holds the cables? Which parts of the bridge are in tension and which are in

compression?

The process of constructing the model is calibrated to the abilities and ages of the students. First grade students will need more help with some of the more difficult hooks and cables on the suspension bridge, for example, than will the fifth grade students. However, the assistance is only a matter of degree, because almost all kids have a natural affinity for block play.

After the model is built, class discussion proceeds to more general aspects of engineering. The students are asked to compare and contrast the model bridge with others they’ve seen. The students learn that the math they’re studying will be used in the future if they want to become

bridge engineers. Having college students in the room, coupled with discussion of the next steps of what the kids will learn, helps illustrate this point well.

Overall, the class experience is one of active learning combined with well-timed discussions. The combination of talking and doing adds excitement to the class and helps engage students in the learning process.

APPLICATIONS AND DISCUSSION

The Commonwealth of Massachusetts now formally requires engineering content in K-12 instruction. This project provides an effective way to introduce required engineering curriculum into grades K-12. Participation in the Tufts Buildable Bridge project includes specified content formally required as part of the K-12 curriculum [9], such as, for example, discussion and demonstration of the concepts of tension and compression.

The Tufts Buildable Bridge project is an application of block play that has something of value for all participants. Grade school students participate in an interactive engineering and science lesson based on an activity that is associated with play. University students mimic, at a more advanced level, the entire process of conceiving, designing, and producing engineering work. The university students design bridge models and use engineering tools to document them. The university students hone their presentation and reporting skills, and these skills are considered of increasing importance for future, successful civil engineers [7]. In a similar outreach project hosted at Tufts University, it was found that time spent in a K-12 classroom lead to improved communication skills, confidence awareness of K-12 educational needs, and in some cases a strengthening of the students’ own engineering knowledge [8]. Senior members of the team, whether practicing engineers or educators, get to interact with future engineers of two different age groups. Besides being an excellent educational tool, the format is a successful application of engineering outreach. The project cuts across a barrier between K-12 and university education, by bringing college students into the grade school classroom. Traditionally, K-12 and university education have been separated, but recent trends seen in ASEE, IEEE and other national societies are valuing K-12 outreach and breaking down the barrier between these levels of education. This project provides a simple platform for increasing the number of engineers on a university and professional level who do

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outreach to K-12 classrooms. The result is a stronger continuum of education that carries from K-12 to college, and then further into the workplace. A key objective of the lesson is to illustrate the connection and path of what is being taught and how the lessons are to be applied later. Grade school students are naturally in awe of college-age kids, with whom they can more readily identify with than adults. A discussion of how 5th grade math leads to college math, and then seeing the implementation of what they’ve learned through the building of a giant suspension bridge, can be exciting for the grade school kids. The process helps to make the teaching more relevant and provide a sense of continuity and cohesiveness to the lesson.

A unique feature of the Buildable Bridge project is its ability to demonstrate methods of construction staging. The bridge models must be built one stage at a time, and they undergo temporary conditions that are very different from the final state. For example, the arch bridge model doesn’t just appear as an arch bridge, but must be assembled using temporary construction cables prior to installation of the keystone pieces. Illustration of construction staging methods through block models is effective not only because it shows the temporary construction stages, but gives the student builder the opportunity to alter the sequence and observe effects. For example, students quickly experience the structural instability resulting from not using the balanced cantilever method in constructing the cable stayed bridge model.

TACOMA NARROWS BRIDGE LESSONS PLAN

A recent addition to the bridge library is the Tacoma Narrows Bridge model. A group of Tufts University first year students were challenged to build a model that simulated the demise of the original Tacoma Narrows Bridge.

The original structure opened in July 1940 and collapsed that November. During construction, the original bridge became well known for its vibration and movement. After opening day and during its brief lifespan, the structure was known as “Galloping Gertie” because of the gentle undulations and swaying motion of the deck. On November 7, 1940, the gentle motion magnified into a violent twisting of the deck

during a gale force wind storm. After several hours of twisting, the span ripped apart and plunged into the Narrows. Thanks to the structure’s notoriety and slow development of the disaster, crews were available to film the structural failure. The video clip is popular to this day.

After the bridge failure, engineers addressed suspension bridge wind resistance in two ways. Many suspensions bridges, such as the Mackinac Bridge had the addition of a stiffening truss. Later designs feature an aerodynamic deck shape [10]. The Tufts model is shown in Figure 4. During a presentation of this model, the deck fails during a student-induced wind storm, provided by fanning the side of the bridge. Next, the deck is rebuilt with the addition of a stiffening truss on the deck. During a subsequent wind storm, the deck remains intact.

Figure 4: Tacoma Narrows Bridge

FUTURE WORK

The next addition to the bridge library will be a model of a post-tensioned concrete box beam bridge. A group of Tufts University senior civil engineering students are designing this model to simulate three construction methods: cast-in-place, cantilever, and construction by gantry crane. The resulting models have rubber bands used to simulate post-tensioning, and will be more appropriate for older grade school students. Another future step in this project is the development of the educational metrics to study the success of this program. This work will address of the goals of three participating groups: the university students who design the models, the students and/or professional engineers who present the models, and the grade school students to whom the models are

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presented. Supporting this study will be measurement approaches developed by the Massachusetts Department of Education Science and Technology/Engineering Curriculum Framework, the Accreditation Board for Engineering and Technology criteria for an undergraduate civil engineering education, and the American Society of Civil Engineers Body of Knowledge, along with traditional systems of measurement, such as Bloom’s Taxonomy of Educational Objectives.

SUMMARY

Tufts University has developed a program to design and construct buildable wood bridge models. The program successfully cuts across generations and involves students, educators and practitioners fulfilling different roles according to their educational needs and abilities. The program promotes active learning in the class room, and helps to cross boundaries between K-12 and university education. The program appeals to grade school students’ natural curiosity and desire for block play. The students think they are playing, but they are at the same time actively learning basic engineering concepts. This is a proven effective way to teach and learn.

ACKNOWLEDGEMENTS

Thanks to the Boston Foundation for Architecture for supporting this work.

REFERENCES

[1] Hirsch, H.K., The Block Book, National Association for the

Education of Young Children, Washington, D.C., 1996. [2] Cuffaro, H.K., Block Building: Opportunities for Learning,

Community Products Limited, United Kingdom, 2005. <http://www.communityplaythings.co.uk/c/resourcesuk/articles/cpd/buildingachildsmind.htm>

[3] Phelps, P.C. and Stannard, L.L., Children's Blocks and Constructive Play, Community Products Limited, United Kingdom, 2005. <http://www.communityplaythings.co.uk/c/ResourcesUK/Articles/BlockEssay.htm>

[4] LeFebvre, J.E., Blocks: The Best Toy You Can Buy, Better Kid Care – Satellite Child Care Training Program, Penn State, April, 1999. <http://www.uwex.edu/ces/flp/pp/pdf/blocks.pdf>

[5] Chalufour, I., Hoisington, C., Moriarty, R., Winokur, J. and Worth, K., The Science and Mathematics of Building Structures, Science and Children, Virginia, 2004. <http://cse.edc.org/pdfs/products/sciMathBldgStruct012004.pdf>

[6] Ansel, P.G., Kids/Blocks/Learning, Yale-New Haven Teachers Institute, Connecticut, 2005. http://www.yale.edu/ynhti/curriculum/units/1993/1/93.01.01.x.html#t

[7] American Society of Civil Engineers, “Civil Engineering Body of Knowledge for the 21st Century”, Reston Virginia, 2004.

[8] Gravel, B., Cunningham, C, Knight, M, Gravel, R., “Learning through Teaching: A Longitudinal Study on the Effects of GK-12 Programs on Teaching Fellows”, Proceedings of the 2005 American Society for Engineering Education Annual Conference & Exposition, Session 2510, Portland, Oregon.

[9] Massachusetts Department of Education. Science and Technology/Engineering Curriculum Framework. Malden, MA: 2001

[10] Scott, Richard, “In the Wake of Tacoma: Suspension Bridges and the Quest for Aerodynamic Stability”, ASCE Press: 2001.

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Brian Brenner ([email protected]; 617-627-3761) received his B.S. and M.S. degrees in Civil Engineering from the Massachusetts Institute of Technology in 1982 and 1984. Brian is Professor of Practice at Tufts University, teaching classes in concrete design, bridge analysis and design, and introduction to engineering. His research includes long term bridge design, structural parameter estimation, and topics in engineering education. Prior to his appointment at Tufts, he was a practicing structural engineer with Parsons Brinckerhoff in Boston. Professor Brenner has published over 70 papers and articles on topics of structural analysis and design, design for construction mitigation, engineering education, computer aided design and other topics. He is Editor Emeritus of the Journal of Professional Issues in Engineering Education and Practice, the education journal of the American Society of Civil Engineers, and Associate Editor of the Journal of Leadership and Management in Engineering. He is chair emeritus of the publications committee of Civil Engineering Practice, the Journal of the Boston Society of Civil Engineers, and he is active in several BSCES and ASCE committees. Professor Brenner received the BSCES President’s Award in 2000, the Clemens Herschel Award in 2001, and the Richard R.Torrens Award from ASCE in 2005. Brian Gravel received his B.S. and M.S. in Mechanical Engineering from Tufts University in 2001 and 2004 respectively. While in graduate school, Brian was an NSF Fellow which included teaching engineering in 9th and 5th grade classrooms in area towns. Brian is now a Program Manager at the Tufts Center for Engineering Educational Outreach (CEEO) and continues work with engineering education and using animation as a tool for teaching mathematics and science. Julia Carroll received her B.S. in Civil and Environmental Engineering from Carnegie Mellon University in 2005. Julia is currently an M.S. candidate in structural engineering at Tufts University, conducting research in engineering education.