How Do You Calculate Member Forces Using the Unit Load Method?

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Calculating member forces using the unit load method can be challenging, especially with statically indeterminate structures. The discussion highlights a student's struggle to express member forces solely in terms of a virtual load P due to the presence of multiple pin joints and bars. It is noted that classmates are simplifying the problem by removing members to achieve a determinate structure, which is not covered in the course material. The importance of understanding the concept of static indeterminacy is emphasized for proper analysis. Further inquiries related to the topic are welcomed for clarification.
EngineeringDave
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Hi I was hoping someone could clear something up for me, I've been set an virtual load (unit load method) question at University, that part of the question I can do however its the calculating the force on the members part that I am struggling with.

The question asks for all the forces in the members as a function of load P using the unit load method, however as there are 4 pin joints (Ay and Bx can cancel) and 4 bars using any equilibrium, joints or moment calcs I can't get each member only in terms of P.

Other students have removed members to do this however as this "method" they are using isn't in the course note and I can't find it online I don't want to just assume they are right.

I've drawn the system In the file uploaded.

Thanks In Advance

Dave
 

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I think your frame is statically indeterminate. Your classmates are removing members in order to make the resulting determinate. It's much easier to apply the various analysis techniques to a determinate structure, in order to determine the additional equation or equations necessary to allow solution.
 
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Okay thanks, I will research this today as I am unfamiliar with the concept.

Thanks Steamking

P.S can I message you with a related quire if I have one?
 

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