Post 8 - Thursday, May 31, 2012:
I35 Bridge Collapse Report
--------------------------------

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
--------------------------------

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
--------------------------------

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
--------------------------------

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
--------------------------------

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

Post 3 - Friday, April 27, 2012:
K'nex Bridge Competition
--------------------------------

In the bridge competition, our bridge was only able to hold 10 lbs. of weight before breaking.

The rules have been updated now so that the bridge height must be between 8''-19.5'', this new rule adds a new element to the contest. Now we can spend less pieces on the height, and focus more on the span. In addition, we realized that we had less blue pieces than all the other groups, so we picked up more blue pieces.

Our final design now incorporates a 45 degree angle connecting the pillars to the span as to reduce stress throughout the entire bridge as opposed to just the span and tops of the pillars. As you can see below in figure 1, the bridge also has 360 degree connectors between each level of the span to reduce stress in all directions on the span. Finally in figure 2, you can see the design as a whole for the final competition. We tested the bridge and it was able to hold 20 lbs on the bridge for one minute.

Figure 1 - The bridge inner level incorporating the 360 degree connectors

Figure 2 - The bridge with 45 degree connections from the pillar to the span

Post 2 - Friday, April 20, 2012:
K'nex Bridge Competition
--------------------------------

We finally finished our bridge for the competition in class. The bridge had to have the following requirements in order to compete:

- composed of less than 400 pieces
- must be at least 19.5" tall with 0.5"
- horizontal span of 35"
- vertical span of 8"

Throughout the building process, our group brainstormed three different ideas.

The first idea was a triangle piece that would lay in a V container. The bridge was supposedly to sit and just lay in the V container. However, while we were building the model, we decided to test it before it had reached the full 35". Even at ~25" the model could not hold 20 pounds and so we scrapped it.

Figure 1 - 3D model of bridge span

Figure 2 - 2D side view of bridge tower

Figure 3 - Photograph of bridge model

Our second idea consisted of a special "box" design that was repeated across the bridge. The box resembles an atom with multiple yellow pieces connecting the central atom to the outside corners. This design was able to hold a large amount of weight and was surprisingly strong and handy. We repeated these cells of atoms through horizontal bars which eventually became the bridge. The problem with the bridge was that the connections between the different cells were not strong and the rods were forced and therefore the bridge span was not able to hold more than 20 lbs. 

Figure 4 - Cell of the 'atom model'

Figure 5 - 3D rendering of the bridge tower

Post 1 - Friday, April 13, 2012:
K'nex Bridge Competition
--------------------------------

The blog was created. We will be meeting Sunday (4/15) to build the bridge. We looked at several different types of bridges and will begin brainstorming the most effective design to use for this project.

Catdog is awesome.

Group Members:
Asher Breverman, abb56@drexel.edu
Nick DiMemmo, njd55@drexel.edu
Patrick Carvalho, pmc62@drexel.edu
Hawra AlMutaily, ha366@drexel.edu
Daniel Borejdo, dborejdo@gmail.com