Last week during lab each group got to test the 2 foot bridge each group made. After a miscommunication about who was supposed to bring the bridge to class we were able to make minor tweaks to try and get the bridge cost down while making the strength of the bridge increase. We also had to make the bridge slightly longer because we made the bridge exactly 2 feet long and it wouldn’t sit on the supports that were used for the test. Furthermore the cost of our bridge was through the roof and we need to change the outlook we have when building the 3 foot long bridge. The total cost was somewhere around $375,000 which was far more than any other bridge, but our bridge did hold 39.4 lbs. which we all believe was an amazing feat. For when we are building the 3 foot bridge I think that we should lower the cost by not using grooved gusset plates which, when tallying up the total amount, were the biggest contributors to the cost.
For lab if I could see some of the forces that West Point Bridge Design shows you I would really want to see where the tension is specifically on the gusset plates. The reasoning behind this is that when every bridge in lab broke it was at a point where a gusset plate had a connection. I personally do not believe that compression would be necessary to see because the Knex pieces are pretty strong and the only weak part that I see is at the point of connection with the gusset plate. I would like to be able to test our 3 foot bridge more in lab before actually putting back into the competition so that we can get a better feel of what exactly is going wrong with our bridge so we can fix it and try again rather than just thinking in theory about how we could possibly make our bridge better. Or goal for next lab is to definitely get our cost to weight ratio down so we have a better chance of being the best bring next time.
-Robert LaChance
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