Throughout the process of building our bridge, many steps were taken in order to ensure that our bridge would have en extremely high, maximum load capacity.We only used the bridge design from the digital bridge a little bit. We used a truss system on top of the bridge but other than that we started with a clean slate for the virtual bridge. At first, we had planned to make a truss bridge with an arch running underneath it to better support it, but the designed was changed so that the bridge could hold more weight. Our new design was based off of that of a simple truss design with a number of trusses placed across the top of the bridge, and a deck layered with six, long pieces of balsa wood. At the end of each pair of trusses were joints that had been cut into square shapes to improve the bridge’s stability, as well as thin pieces of balsa wood that ran the length of the bridge on the points where the trusses touched the bridge, and along the top in between them. In the middle of the deck was a space where short pieces of balsa wood were placed in a diagonal pattern to increase the load capacity.
Before we began cutting any balsa wood, both designs had been drawn and scaled by Kyle Bonci on graphing paper, to make sure that our bridge would fit into the desired space. We began to measure and cut our trusses on the second and following days of class, so that we would be able to begin gluing our bridge together as soon as possible. After several class periods spent on gluing the bridge pieces together, during Easter Break, and towards the end of the project, Bryan Fay had brought the bridge home to his house to finish the bridge. On the testing day for our bridge, ours had gone last after watching many bridges break apart from the weight of the bricks. When we began to load the bucket attached to our bridge with bricks, we began to notice that our bridge wasn’t budging, and after using all the available bricks, our bridge had survived. The main reason for our bridge being able to handle the large amount of weight from the bricks, which was 417 newtons or around 95 pounds of force, was because of the large trusses on our bridge that diverted the force of the bricks and gravity away from the main area of pressure on the bridge, which had been where the bucket was hanging from. Another ideal part of our design was the thickness of our bridge deck and its layering, which greatly reduced the pressure the bucket of bricks had on it. Even though almost 100 pounds of force was placed upon it, our bridge “Girthy,” was able to survive and remain intact, one of only three bridges left in the competition