A3- Bell

For this assignment, the task was to analyze a truss bridge so we could get an idea of how much force of compression/tension was on each member. For my truss, it was said to be 24 inches long, 6 inches high, and to have a load held from the center at the bottom of 10 pounds. It was just simple trigonometry and force diagrams to figure out the force on each member both in pounds and in newtons. The results of my truss analysis is as follows:

Figure 1: The front page of the truss analysis

At the top of this page, I have the initial truss design. Then, I go into more detail about each individual triangle, finding out the lengths of the members and the angle of the joints. At the bottom, I was able to find out the weight that the two end joints receive when the load is in place. 

Figure 2: The back page of the truss analysis

This page includes all the weights/forces on each member. Across from their calculations is a free body diagram of the joint with all the appropriate forces labeled. At the bottom is all the forces on the members in Newtons and pounds.

In order to ensure that these calculations are bother accurate and indeed correct, an online program (Bridge Designer) has been created to do all this work for us. Just by simply drawing the bridge with your specific measurements, the program returns numbers on each member in pounds. In addition, the final results are color coated; red codes for tension and blue codes for compression (as seen in the figure):

Figure 3: Truss analysis using Bridge Designer

As you can see in the picture, my results that I received from Bridge Designer were very similar to that of my hand-written truss analysis. The advantage to this program is that my truss doesn't have to be to scale with the actual dimensions. 

In my truss analysis, I had to scale the bridge. Regardless, I still kept the same shape of the truss, so the design/dimensions wouldn't change. Each block in the Bridge Designer truss analysis is 3 inches. As long as everything is scaled correctly, everything should come out as the same numbers as the hand-written analysis. 

Figure 4: K'nex bridge analysis using Bridge Designer 

In this image, we have the K'nex bridge design that we have been testing in class for the past week or two. However, it is not exact. The member that seems to be missing in the middle is due to the limitations of the Bridge Designer program. Nonetheless, this program still comes in handy. Now, we can analyze which member is the weakest or closest to its breaking point. Through this program, we can make accurate modifications to our bridge to improve its durability and ability to hold weight.