Week 6 - Yilei Jiang

         This week, we built our own design K'nex bridge to see which one was the best one and the good components of the designs.  We decided to build a design which without bottom truss. Besides, it was also the design which had the lowest budget. After we done, I found one thing during the testing that the weakest part of this bridge was those grooved gusset plates. They were always pulled apart when we was adding the weight. Especially, the gussets from two piers of the bridge were so easy to separate.  I thought that the reason was  the bridge had one-side truss. So I suggested to build the bridge with top and bottom truss. However, the testing result was same. Our second design only could hold 20 pounds before it was fallen to pieces. Then we started to think about the reason. And I felt that we could shorten the height of the bridge because it can support well. Our original base was the structure like this" |\|\|\/|/|/|". And now if we change 5"long chords to 1.25" long chords, the bridge's structure will like " |\/|><|/\| ", which I think can be more stable. The other idea is that we decide to use more groove-less gussets to avoid using grooved gussets. That can not reduce the cost but make the bridge into pieces easily.
      
        For the next week, After working with Knex for a week reread we entry of last week and state how our views of the similarities and differences have changed. Then we will test our design on a 20' span. And we will fill out the bridge results recording before we leave the class.