The prior week, we designed our final bridge for the next week when we will actually test out the bridge. Instead of building a bridge that could hold a huge amount of weight and cost a lot of money, I decided to build a bridge that could only hold a little bit of weight, but is cheap so that the cost to performance ratio is high. I ended up building a bridge with a basic over truss design with many right triangles. I also used the long seven inch Knex pieces and used less gussets because the weak points were at the gussets on the previous bridges we looked at. I also designed it so The cost is about $100,000 and when we tested it, it held 14.4 pounds. This is pretty good cost performance. Disel in my group designed a bridge that had more webs and smaller trusses, but when we tested it, it only held 7 pounds and it cost a lot more than my bridge design so we decided to go with my design. Disel's bridge broke more easily probably because he had many gussets and connectors which made it easier to break. He also had the sliding gusset plates which is a common place where the bridge ruptures. The coming week, we will test out my bridge design for the final test. We will try to make the bride cheaper and stronger in preparation for the final test to improve the cost performance. The major accomplishment this week was that we were able to design a bridge that will look very close to the final design. The bridge we have right now follows all the restrictions and we are happy with how it performed when we tested it. The only thing to do now is to improve on it. The problem is that I am not sure how to improve on it. I have made the bridge as cheap as possible for the current design, and I do not know if there are parts that I can remove. Otherwise, there are no problems within the team. We all agree with the current bridge design and we are helping each other out giving ideas for the bridge.
I learned that you must consider many things when you are designing a bridge. There are many steps when designing a bridge. One of the most important things that one must consider when designing a bridge is what the client wants the bridge to be. Does he want the sturdiest, strongest bridge possible or a very cheap bridge that is not as strong? Does it have to look interesting and unique with a suave design, because it will be a symbol of a city? In this course, we were required to build a bridge with the best cost performance. We had to balance out how much it can hold, with how much it costs. Another thing that is very important is considering the restrictions. A real bridge will definitely need to span a certain distance, be able to hold at least a certain amount, be durable so it will last for a long time, and there could also be a cost range. There are many restrictions that must be followed. In this course, for example, the final bridge for next week must span 36 inches and must have a hollow inside section 3 inches wide and 2 inches tall. After you have all these things, you can start designing your bridge. When designing bridges, you must also think about how the forces of tension and compression are distributed throughout the bridge. In the course, we used basic laws of physics to see how forces of weight were distributed throughout the members of the bridge. One thing you have to remember when dong these calculations is that this is disregarding many factors such as wind and the weight of the bridge itself. For this reason, we can only use these as a reference. One more thing I learned in designing bridges is that triangles are very strong stable shapes so are good to use in the designs. This is because in a two dimensional plane you cannot change the shape of triangles once you have one unlike rectangles where you can slide a side and make a different shape.
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