Triangles, Trusses, and Trigonometry
The first unit in the class Urban Planning was Load. We have spent the past few weeks learning about bridges and how trigonometry is used in them. We have learned and applied the law of sines, the law of cosines, the area of triangles, and more. We also met an urban planner who took us on a walk around downtown Chicago and showed us the DuSable Bridge which is a combination of a truss bridge and a drawbridge. Another subject we learned about was physics. We learned about vectors, free body diagrams, gravity, acceleration, velocity, and how physics applies to the design of bridges.
For this project, we are applying what we have learned about forces and are using 75 popsicle sticks and glue as our only supplies to make a bridge. We were tasked to make a truss bridge that could span a gap of 18 inches and withstand 10 pounds.
One bridge that provided inspiration for this project is the DuSable Bridge which crosses the Chicago River at Michigan Ave. It is a double-layered truss and drawbridge. It gave me inspiration because it is able to combine the design of multiple bridges into one and it does its job very effectively and withstands the high traffic it sees on a daily basis.
The design for my bridge was chosen along the way and going into the project there wasn't any specific plan. We were originally going to make a warren truss bridge but that proved difficult due to the lack of variety in the length of our materials. We eventually chose to create a double intersection bridge with some modifications which became our final design.
The final bridge was made of 70 popsicle sticks. It was 19.5 inches long, 2.25 inches tall, and 2.25 inches wide. When it was tested it was able to hold up to 25 pounds without breaking.
While creating our bridge we realized we wouldn't have enough popsicle sticks if we continued with the envisioned idea. To combat this we cut our already-made rectangles in half to make them shorter which meant we wouldn't need to use as many popsicles sticks for the diagonals. This also allowed us to make an additional side which made our bridge denser and sturdier.
The eleventh sustainable design goal is to “Make cities and human settlements inclusive, safe, resilient and sustainable.” The bridge I created applies to this goal because it was able to be made with limited resources and is very strong and resilient. Upon testing it was able to hold 25 pounds without breaking proving its strength.
For this project, we are applying what we have learned about forces and are using 75 popsicle sticks and glue as our only supplies to make a bridge. We were tasked to make a truss bridge that could span a gap of 18 inches and withstand 10 pounds.
One bridge that provided inspiration for this project is the DuSable Bridge which crosses the Chicago River at Michigan Ave. It is a double-layered truss and drawbridge. It gave me inspiration because it is able to combine the design of multiple bridges into one and it does its job very effectively and withstands the high traffic it sees on a daily basis.
Dusable Bridge - Chicago Architecture Center - 2023
The design for my bridge was chosen along the way and going into the project there wasn't any specific plan. We were originally going to make a warren truss bridge but that proved difficult due to the lack of variety in the length of our materials. We eventually chose to create a double intersection bridge with some modifications which became our final design.
Labeled bridge sketch - PC - 2023
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Scale digital bridge sketch - PC - 2023
In this unit, we learned about potential energy and kinetic energy. To calculate these for my bridge I used the following equations
PE = height x gravity x mass
KE = 1/2 x mass x velocity^2
I was able to weigh my bridge to get the mass and the gravity and height were given to me
PE = .9m x 9.6 m/s/s x 0.0751kg
PE = 0.662382 J
In order to calculate the kinetic energy of my bridge I first had to find its final velocity
Vf^2 = Vi^2 + 2 x a x d
Vf^2 = 0^2 + 2 x 9.8 x .9
Vf^2 = 17.64
Vf = 4.2
Now that I have the velocity I can use the original equation to find the kinetic energy
KE = 1/2 x 0.0751kg x 4.2^2
KE = 0.662382 J
The kinetic energy is equal to the potential energy. This is found to be true because of the Law of Conservation of Evergy which says that energy cannot be lost or gained, it just transfers state.
To apply the trigonometric principles we learned, I used the Law of Sines and the Law of Cosines to find the inner angles of the triangle that was created on the sides of the truss bridge.
Triangular truss measurements - PC - 2023
Bridge test - PC - 2023
While creating our bridge we realized we wouldn't have enough popsicle sticks if we continued with the envisioned idea. To combat this we cut our already-made rectangles in half to make them shorter which meant we wouldn't need to use as many popsicles sticks for the diagonals. This also allowed us to make an additional side which made our bridge denser and sturdier.
The eleventh sustainable design goal is to “Make cities and human settlements inclusive, safe, resilient and sustainable.” The bridge I created applies to this goal because it was able to be made with limited resources and is very strong and resilient. Upon testing it was able to hold 25 pounds without breaking proving its strength.
I found this Action Project to be very enjoyable because I love getting to create models and working with my hands. I wish I had been able to spend more time preparing for what type of bridge I was creating so that it would be able to be more uniform and planned out. I also wish I had chosen a different partner because I ended up doing most of the work myself. Despite the setbacks, I think my bridge turned out wonderfully and I am so proud of how it was able to hold up to the testing. After we tested it I got to destroy the bridge which was super fun.
Burning bridge - PC - 2023
wooooo
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