Post 8 - Thursday, May 31, 2012:
I35 Bridge Collapse Report
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One of the original ideas for the collapse of I35 was the particular deicing agent that was used on the bridge. The particular icing agent was determined to be Potassium Acetate. However, after further research we determined that this was not the cause for the collapse but may have been an important factor.

Figure 1 - Model of the I35 Bridge

After further research, we were able to determine that the leading factor that lead to the collapse of the I35 was the failure of the diagonal truss U10-L11. That particular truss can be seen below:

Figure 2 - U10/L11 Truss that failed

Figure 3 - Side view of the zone that broke under the stress

"The diagonal truss member U10-L11 carried the tension stress with the highest amplitude among all of the main truss members… therefore, the majority of the vertical load on this node was balanced by the compression force and bending moment carried by the diagonal member U10-L9."
( ASCE, http://suhao-acii.com/files/I35W_note.pdf )

Post 7 - Thursday, May 31, 2012:
K'nex Bridge Competition
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After two weeks of building and planning, our group was finally able to construct a final design for the second design project of the K'nex Bridge competition. We constructed a bridge that used a similar X design on the sides of each block while adjusting the previous design to fix the new constraints of the bridge. We also modified the end of the bridge to be much stronger and to connect with the legs in a much stronger connection.

Figure 1 - Amount of connectors and rods 

Figure 2 - 3D photograph of the bridge design

Figure 3 - Side view of the bridge's leg

Post 6 - Saturday, May 12, 2012:
K'nex Bridge Competition
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After meeting with Dr. Aktan, our group began brainstorming our tasks for this week.

K'nex Bridge -

The requirements for the new bridge is that it spans a length of 4' (from tower to tower) and has a height of 19.5". Just like last competition, the bridge has a maximum of 400 pieces. However, the goal of this particular competition is to replace an already-standing bridge. Because of that, we are only instructed to build the span of the bridge and not the towers. This will allow us to allocate all our pieces into fortifying the bridge and making it stronger and longer.

Minnesota I35 Collapse -

Our group will begin researching the collapse of Interstate 35 in Minnesota. After watching footage of the bridge and finding general information about the collapse, we began researching detailed reports and other information.

Post 5 - Monday, May 7, 2012:
K'nex Bridge Competition
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The report for the bridge competition was submitted today by 5 PM.

In last week's class, our group picked the following topic for the upcoming project:

Structural Design:
(a) Study and report on the 2007 Minnesota I35 Bridge Collapse, all the reasons
that have been stipulated for the collapse, and the measures that have been proposed/taken for
mitigating such collapses
(b) Continue to optimize the Knex Bridge design.

More information will be updated once we have begun the planning process.

Post 4 - Sunday, April 27, 2012:
K'nex Bridge Competition
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In the competition in class our bridge placed 2nd out of five teams. Overall there were four bridges that could hold the required weight and out of those four, two teams were penalized for not adhering to the requirements. The winning team's bridge held the required weight and had the least amount of building costs. Our bridge had the second least building cost with a price of approximately $50,000. In conclusion, the bridge we built was a good strong bridge that was able to hold a little bit more than 20 lbs. We could have probably found ways to take away a couple knex pieces around the entire bridge to reduce cost but we decided to stick with a bridge that could hold a little bit more. As you can see below in figure 1, the bridge was structurally sound and able to hold 20 lbs.

Figure 1 - Second place bridge of the knex bridge building competition