A3 - Zhu

1. Method of Joints

2. Results of Analysis

3. Online Bridge Designer Replicate

4.

In order for the lengths of the hand analysis to correspond to online Bridge Designer, the lengths of the members must be scaled equally to the Bridge Designer. In Bridge Designer, each grid is 2x2x2 inches. In my case, the length of my bridge needs to be 36 inches; so on Bridge Designer, my bridge needs to cover 18 grids. Then, the amount of load I need to add is measured in Newtons—20 pounds is approximately 90.7 N; therefore, I added 90N to the midpoint of the Truss.

5. Bridge Designer For Knex Truss

The automatic calculation feature on Bridge Designer has calculated the forces on each member of the bridge. According to the logic I used in #4, each grid should be 2'', and the load should be measured in Newtons.

6. Final Analysis - How to use this analysis to improve the bridge design?

The calculated tension force and compression force will enable us to improve our cost to strength ratio of our bridge. If there's too much force on certain members, it means that we have to adjust the location of the pieces and perhaps change the design up a little bit. On the other side, if the members show little to no force, we can eliminate them to lower the overall cost. According to the Knex joints web page, the more members that are connected to a connector, the more stable the bridge. The pull out force increases as the number of members increases. Using this piece of information, I learned that we should change our design a little bit so that most of the connectors have more than one members going in an angle less than 90 degrees.