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

2. 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

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

4. 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?

5. 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%

6. 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

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

8. 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

9. 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

10. 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

11. 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

12. 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.

13. 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.

14. 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

15. 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

16. 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

17. 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

18. Works cited
Historyofbridges.com,. (2015). Bridge Types - Different Types of Bridges. Retrieved 11 June 2015, from
Mathsinthecity.com,. (2015). Most stable shape- triangle | Maths in the City. Retrieved 11 June 2015, from
Pbs.org,. (2015). BUILDING BIG: Forces Lab. Retrieved 11 June 2015, from
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