Bell Weekly Blog- Week 9

In week 8, the group constructed and tested our bridge that spanned 36”. We had the idea in our heads but never actually put anything to the test until week 8’s class. During this test, we analyzed our results to see which bridge had the best cost to strength ratio. The first 36” bridge seemed to have a better ratio than the second 36” bridge, but only slightly. The final bridge design held 35 lbs. and cost $297,000. Considering the large span that the bridge had to reach, I feel that our bridge held a significant amount of weight. In this coming week (week 9), our group has agreed to continue the analysis of our bridge. If need be, we will make slight adjustments to improve our design. The major accomplishments for our group for the week include constructing a bridge with a good cost to strength ratio. Constructing a bridge that spans 36” was difficult enough; having a good cost to strength ratio was the challenging part. Some issues that the team might run into could be differing opinions on what types of adjustments we should make to our bridge. If we disagree, we will have to try and see if we can work something out that most, and hopefully everyone can agree on.

There are many things that I have learned about in my bridge design. The very first thing I learned about bridges was the term “truss.” Trusses are the building blocks to a successful bridge. Furthermore, we learned how to apply these trusses in in different orientations. It was good that the groups got to play around with the K’nex to get some ideas about what makes a good, strong, yet serviceable bridge. We also learned about which members experience tension and which experience compression. In WPBD, our group played around with changing materials and thicknesses to max out the most members possible with tension and compression. This was done because the goal of this whole project is to have a serviceable bridge that was as cheap as possible. Throughout the weeks, I learned especially that the main focus needs to be in the center of the bridge. The center will have the majority of the weight, so more thought must be given to it. More specifically in our class, there were different things to consider, being that we used K’nex pieces instead of cement, steel, etc. (real bridge materials) So, like I have said in multiple previous posts, the part where the bridge always gives out is the bottom part of the bridge where the members connect to the joints. This was ultimately due to the exceeding tension force. However, throughout this term, I have gained quite a large deal of knowledge about bridges.