Week 2

In our second week, we studied civil engineering! We worked with a bridge building software which allowed us to build a 2d bridge and test it. Afterwards, we used a 3d software to create bridge out of balsa wood. We ran hundreds of tests as a team in order to optimize the cost and strength of the bridges.

Civil Engineering and Building Science

Civil Engineering is the process of designing, constructing and maintaining structures. Civil Engineers have the difficult task of creating long lasting structures that can support massive amounts of weight and are in a budget all while making sure that they have visual appeal. Civil engineers and building science has to be incredibly precise as buildings need to be structurally sound so that they don't harm anyone using it. Civil engineers are responsible for structures such as bridges, roads, dams, buildings, canals, pipes, railways, sewage systems, and even airports. Civil engineers have to work with the environment and have to keep in mind various natural challenges that their structure might face. For example buildings have to survive earthquakes, and bridges have to survive strong winds.

Design Process:

The 2D software required our team to create a truss-pratt bridge that was 12 feet above the ground. The design requirements were that the price had to be as low as possible, 15 percent of the structure had to be made of hollow tubing, the compression force was to be no more than 0.40 +/- 0.01, and the tension force was to be no more than 0.45 +/- 0.01.

At first, our team used hollow tubes randomly and various sizes of solids bars to achieve a passing structure. However, the cost was in the mid 300 thousands. We began cutting back size where we could but none of us could break into the 200 thousands. So, we experimented with using hollow tubes in many different places to see how they would affect the total cost of the structure. Finally, we targeted the most expensive areas of the bridge and replaced them with hollow tubing to reduce the cost. Then we went through the bridge decreasing the size of the solid bars but making sure that they fell within the 0.4 compression force and 0.45 tension force. The lowest cost that we achieved was 290,101.54 dollars.

The 3D software also had many requirements. To begin with the bridge would have to be at least 4 feet long (spanning at least three feet), elevated one foot off the ground and it must use balsa wood.

Similarly to the 2D software, we used trial and error to optimize our design, however, since we did not have to follow a specific set of requirements such as a truss-pratt design or a specific truss length so we decided to make two different designs while using trial and error to find out how much weight each bridge could take. This resulted in two very different bridges with one design being able to take a total of 500 lb while the other could take 900 lb!

Here is our 2D Bridge Design:

Final Bridge Design

A screenshot of our best bridge was cost us $290,101.54

2D Bridge Design Load Test Results

Bridge Calculation Values

This is the spreasheet of our data for the bridge.

A program view of our data

After copy and pasting the data from the program we wanted to also include the tension and compression ratios.

Here is our 3D bridge:

Design Inspiration

For the bridge I found reading online that underneath truss are more tension then compression based. I wanted to use a tension based bridge since either in our lecture or online I found the balsa wood is stronger in tension then in compression. This was also why I chose the pratt truss because through research the pratt truss is more tension then compression compared to the Howe or Warren truss. This is why the superstructure bridge uses the pratt truss.

Before Optimization

I first had issues with bridge doing it first analysis. I don't know why because when I loaded the file up the next day it work fine. This may have been because I moved the piers in. As you can see in the photo every member is the same size, this is due to change.

Final Bridge Design

The dimensions of the bridge are, 48 inches by 12 inches by 24 inches. Through trail and error of going from 10lb of force to 450lb of force each side. I would incrementally increase the size of the bridge where the members would turn red.

Alternative Bridge Designs

Each one of us had a go at either one or both of the softwares in making a bridge. Here are some our designs:

Here is an early 2D Bridge

This was our other 3D bridge

This is one of the other 2D Bridges that was a success but too expensive

This is a closer to finished bridge that was again more expensive

Week 2 Team 5 Research Paper

Final Research Paper

To write this paper, we split the work amongst us. We each began by choosing a section that we felt really passionate about. We then got to work and wrote out that segment. We then placed all these sections together to make the paper, edited for clarity, and inserted all of our references.

Research Paper Sources/Planning Document

As a group we decided that we wanted to research about bridges before we started to design them so we could create a well-informed design. To do this each one of us found 5 sources about "The Design Process of Structures including Simulations and Models." Not only helping us with bridge design it made the process of writing the final paper seamless.

Week 2 Research Sources

Week 2 Project Evaluation

Project Evaluation

This week went by so fast, we have tons of laughs with both our team members and our TAs. We learned a lot like how forces move throughout bridges and how things like stress and strain can be applicable and many different fields.

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