A3-JACOB

1.Calculations of forces in  the truss members using the Method of Joints.

Truss Bridge That was used in Method of Joints

Calculation of Forces via Method of Joints (MOJ)  - 1

Calculation of Forces via Method of Joints (MOJ)  -  2

Labeled Diagram showing results of MOJ.

2.Results of the Analysis

From the truss analysis it can be concluded that the members connected to the center node will have tension and the members not connected to the center node will have compression.

 3.

Bridge Designer Image Replicating MOJ

4.

The bridge designer is a very convenient method for calculating the tension and compression of each member in a Truss bridge design. The data collected from hand analysis and the online Bridge Designer is very similar. In order for both analysis to correspond, the length of the members and the angles must scale to each other. In Bridge Designer, each block represents 2 inches in length. Therefore, the ratio between the members must stay the same for the angles to stay the same. 

5.

Bridge Designer Applied to our Knex Truss

6. How to Use Analysis to Improve the Design of Knex Bridge

Using the method of joints analysis, we can determine a value of the tension and compression of members of the bridge for a given load. The testing information about the K’NEX rods and K’NEX connectors provides the tensile pull-out force for various modes of connection. The web page displays three different modes of connections that contain different number of membranes connected to one connector. Analyzing the tensile pull-out force, it is evident that the pull0 out force increases with the number of membranes attached to the connectors. I was also ale to observe that the pull out-force greatly increased going from Mode 2 to Mode 3 rather than Mode 1 to Mode 2. This Tensile pull-out force table is useful in understanding that the how the number of membrane to connector ratio directly correlates with the stability of the bridge. From this information, our objective for this week would be detected the weakest connections and strengthening it by additional membranes.