- #1
endy_kami
- 5
- 0
what are the internal force in the hinged member 1-4?
Internal forces in members of structure
- Thread starter endy_kami
- Start date
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Discussion Overview
The discussion revolves around determining the internal forces in a hinged member of a structural system. Participants explore methods for calculating these forces, including the force method, displacement method, and matrix stiffness method. The conversation includes both theoretical and practical aspects of structural analysis.
Discussion Character
- Technical explanation
- Homework-related
- Debate/contested
Main Points Raised
- One participant inquires about the internal forces in the hinged member 1-4.
- Another participant suggests that the problem is interesting and shares an image to illustrate their approach, assuming the beam is rigid and all bars have the same stiffness.
- A participant expresses gratitude and indicates they will attempt the suggested approach.
- One participant reports their calculated forces (N1=0.6P, N2=0.3P, N3=0.03P, N4=0.07P) but notes a discrepancy with the expected values (N1=0.4P, N2=0.3P, N3=0.2P, N4=0.1P) according to the writer.
- Another participant challenges the correctness of the reported values, suggesting that forces should be larger in rods closer to the load application.
- One participant requests to see the work leading to the reported answer to provide assistance.
- A participant critiques the equations and procedural steps presented by another, pointing out mistakes and questioning the physical validity of a triangle drawn in their work.
- Another participant asks for guidance on how to arrive at the correct answer.
Areas of Agreement / Disagreement
Participants express differing views on the correctness of calculated internal forces, with some asserting that the reported values are incorrect based on expected physical behavior. The discussion remains unresolved, with multiple competing views on the correct approach and calculations.
Contextual Notes
There are indications of procedural mistakes and assumptions that may not be clearly defined, such as the treatment of bar forces and the physical interpretation of drawn diagrams. Specific values and methods remain contested.
- #2
afreiden
- 114
- 3
Interesting problem.
I've attached an image that illustrate my thoughts on how to go about solving it.
I'm assuming the beam is "rigid" and the bars all have the same "stiffness."
Take a look at the image.
Finding the bar forces in the first step is trivial, as the structure is symmetric.
Once you've found the bar forces from step 1 and the bar forces from step 2 (based on my attached image), you can sum them to arrive at your solution.
I drew a red arrow pointing at the second step in the process, which I think needs further explanation. You may find example #2 useful on this website: http://utsv.net/mechanics-of-materials/2-statically-indeterminate-structure-axial
Hope that helps
I've attached an image that illustrate my thoughts on how to go about solving it.
I'm assuming the beam is "rigid" and the bars all have the same "stiffness."
Take a look at the image.
Finding the bar forces in the first step is trivial, as the structure is symmetric.
Once you've found the bar forces from step 1 and the bar forces from step 2 (based on my attached image), you can sum them to arrive at your solution.
I drew a red arrow pointing at the second step in the process, which I think needs further explanation. You may find example #2 useful on this website: http://utsv.net/mechanics-of-materials/2-statically-indeterminate-structure-axial
Hope that helps
Attachments
- #3
endy_kami
- 5
- 0
tx a lot I'll try it
- #4
endy_kami
- 5
- 0
dear afreiden,
I've tried the clue that you've given me
I found N1=0,6P N2=0,3P N3=0,03P N4=0,07P
but the answer should be N1=0,4P N2=0,3P N3=0,2P N4=0,1P (according to the writer)
the writer said use the force method or displacement method or
the matrix stiffness method, any idea?
I've tried the clue that you've given me
I found N1=0,6P N2=0,3P N3=0,03P N4=0,07P
but the answer should be N1=0,4P N2=0,3P N3=0,2P N4=0,1P (according to the writer)
the writer said use the force method or displacement method or
the matrix stiffness method, any idea?
- #5
afreiden
- 114
- 3
Show us your work and we can help. Your answer immediately looks wrong to me since I'd expect the forces to be larger in the rods that are nearer to the point of load application. In the author's solution this is indeed the case.
- #6
endy_kami
- 5
- 0
please find attached on how I got to that answer
- #7
afreiden
- 114
- 3
Your equation that you wrote at the top right of your page (I think it might be labeled (1) ) is definitely wrong.
In general, I see several procedural mistakes.In step 1, all bar forces should be the same.
In step 2:
What is your value of "M" ?
How did you determine that N1=2N2? (I expect to see some axial deformation equations)
Do you understand how I was able to draw that triangle?
Your triangle at the bottom of your page does not make physical sense.
In general, I see several procedural mistakes.In step 1, all bar forces should be the same.
In step 2:
What is your value of "M" ?
How did you determine that N1=2N2? (I expect to see some axial deformation equations)
Do you understand how I was able to draw that triangle?
Your triangle at the bottom of your page does not make physical sense.
- #8
endy_kami
- 5
- 0
can you show me how to get to the right answer than?
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