POPSICLE STICK BRIDGE PROJECT By: Jouya N POPSICLE STICK BRIDGE PROJECT

introduction Unit of Inquiry: Bridge Unit “Can I span the distance?” Statement of Inquiry: Historical inventions have led to great advances in technology. Objective: To design a bridge that can span 30cm and support load. Leonard P. Zakim Bunker Hill Memorial Bridge Design Specifications: A maximum of 75 popsicles used Must span a length of 30cm Superstructure cannot exceed a height of 20cm Substructure cannot exceed a depth of 20cm A maximum of three glue sticks used The Lions Gate Bridge

Design Cycle Research Reflection and testing Create Bridge Bridge Design and Selection

Investigation What forces are applied to a bridge? What shapes are the strongest? Why are those shapes the strongest? What type of bridge supports the most weight?

Planning We chose four bridges that we thought were appropriate to the maximum material list, bridge span minimum, height and depth limit of the structure, and those that we thought were the strongest and would support the most weight. 35% 65%

Research Triangles are a strong shape and are used through out bridges Quadrilaterals are weak structures as they rack easily but can be reinforced with a diagonal beam Beam, truss, arch, and cantilevered bridges are all possibilities for a design

We designed four bridges designs We designed four bridges Double Intersecting warren bridge Cantilevered Bridge Arch Bridge Bowstring Bridge

Double Intersecting warren bridge Pros There are a lot of triangles making it a strong structure Weight is evenly distributed due to design Cons If a popsicle stick is missing the structure could fail There is no substructure to support the structure

Cons Pros Bowstring Bridge Half circles are strong Difficult and time consuming to build Missing popsicle sticks could weaken the structure There is no substructure for extra support Pros Half circles are strong Load is equally distributed It would support weight well

Cantilevered Bridge Pros Cons There is a substructure that provides extra support in preventing tension Weight is well distributed in the structure and supported due to the substructure Cons Structure might fail at weak points at ends Consumes many popsicle sticks just for sides of bridge It’s is the most complicated to build compared to the others

Pros Cons Arch Bridge Force distributed to ends of structure Equal distribution of weight Cons Less support in the middle of structure Structure relies on ends of structure to not fail Large amount of popsicle sticks consumed for just one side of structure

Selected Bridge In the end we decided to create a cantilevered bridge as it has both a superstructure and a substructure that both add extra support to the bridge. We inferred that it would be stronger than the other bridges as the substructure adds extra support against compression and tension. Also, compared to the other bridges, the design is more thought out so it can hold more weight.

Modifying Selected Bridge Observing selected bridge we realized that the ends of the substructure were not supporting the structure that much against tension so we removed them and added them to the deck of the bridge which gave more support against compression and reinforced it. Also, the substructure was not supporting the load in the center so we flipped two of the popsicle sticks creating an X in the middle of the structure adding a lot more support. Finally we add horizontal supports on any equilateral triangles creating right angle triangles. This would add even more support to the structure against racking.

Building Procedure Using the blueprint, we created first one side of the structure working left to right by using wooden popsicle sticks and hot glue Next using paper we copied the blueprint of the side to create a template for making the other side Create the other side using the template Join both sides with more popsicle sticks and hot glue to form a triangle to prevent racking Reinforce any area showing weakness under either compression or tension with left over hot glue or popsicle sticks

Miter Joint Where two materials are cut in such a way to create usually a 45 degree angle corner It creates stronger joints It compresses crowed joints which reinforce and creates a more presentable look to the structure

Testing We inferred that our bridge would hold 60lbs yet it was only able to hold 30lbs We tested the bridge by attaching a chain to a box and gradually increasing the weight of it

Reflection After observing the bridge we realized that our bridge failed under minor weight due to the end of the deck where the bridge failed to be angled. This caused a glue joint to fail since the bridge end tried to right itself forcing it out of place causing the bridge to be pulled down by the load. To prevent this from happening if we took more time and care in make sure that everything was at the right angle. If we were to rebuild this our design would be able to hold a lot more since we now know where the weak points are

Works cited Historyofbridges.com,. (2015). Bridge Types - Different Types of Bridges. Retrieved 11 June 2015, from http://www.historyofbridges.com/facts-about-bridges/types-of-bridges/ Mathsinthecity.com,. (2015). Most stable shape- triangle | Maths in the City. Retrieved 11 June 2015, from http://www.mathsinthecity.com/sites/most-stable-shape-triangle Pbs.org,. (2015). BUILDING BIG: Forces Lab. Retrieved 11 June 2015, from http://www.pbs.org/wgbh/buildingbig/lab/forces.html Google Images