In my opinion, “Method of Joints” for analysis is not sufficient enough for a real bridge in a realistic situation. First of all, the load applied on a real bridge is different than the situation we considered for class where it only has vertical force. A real bridge will have force from all directions, for example the horizontal load from wind. Also the size and type of membranes included on a real bridge will contribute to how much load is actually felt on the joints. Another factor is the constant change of load applied on a real bridge, such as number of vehicles or weather patterns. Therefore, there will be a constant variation of forces applied on each membrane and joints. In addition with “Method of Joints” I would also like to know the strengths of each membrane and joint so I could predict at which forces will the bridge collapse due to the specific parts. One more think I would like to analyze is the failure of the two 180 grooved gusset plates because they are found to be weak and caused our first bridge to easily collapse.
Last week in lab we discussed how to analyze the forces applied on a bridge by using the process called “Method of Joints.” With this method, students are able to learn how to compute tension or compression forces felt on each membrane of the truss bridge. This mathematical tool can help students compute the forces applied on their Knex bridges and make adjustments for a better result. For example, if certain membrane is experiencing a great amount of force, the best method is to make that area strong and compatible for the load applied. This week in class we will finish designing a truss bridge that will span over 36 feet and follows the new constrains. This will be the second bridge that the students will be testing in class.
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