Maybe the following is easier. If you remove the right-hand support, then clearly, that point will move to the left. Therefore, the horizontal reaction at the roller support must be to the right. Horizontal equilibrium means the horizontal reaction at the fixed end must be to the left. Vertical equilibrium means no vertical reaction at the fixed support. Sum of moments about the fixed support means the moment reaction must be anticlockwise since the only force causing moment is the applied load. All reactions are found with certainty. Start drawing the BMD from the right support you will get case D.
Thanks a lot. Your explanations are pretty good. But what if we are not given any options? The fact that we have two options given, and we see the point of contraflexure makes it much easier. How about we are not given any options and have no idea about the zero moment points on the left column?
This answer seems not correct as the righthand horizontal reaction produce zero moment at left support due to zero lever arm and thus the clockwise moment due to horizontal load at left support should be balanced by the reaction moment at the left support itself . then it will a simple triangle without any contraflexure .
Thanks for the explanation- sketching and going through the FBD at the point/s of contraflexure really helps in identifying the correct solution. I would request you to also include, if possible, the qualitative deflection diagrams in all your explanations and spend a couple of minutes on explaining the joint displacements, rotations and sway. I understand this may not be required by the problem statement, but it would really help in reinforcing our understanding of the structural behaviour. I have subscribed to your TH-cam channel and turned on the notifications, and have been following your page on LinkedIn for the great content on structural analysis. PS: Solving the problems along the lines of th-cam.com/video/DUJXu7APzCY/w-d-xo.html would be awesome. PPS: Can a representative screenshot of the FBD & deflection diagrams generated in a commercially available software be also presented as a confirmation of the manually derived qualitative diagrams?
I won’t be able to do all questions due to lack of time but occasionally I suspect some of the most difficult ones will need my explanation. Thanks for the subscription! Please do tell other friends and colleagues about this channel
@@TheStructuralExam Thanks for the reply. Will surely recommend this channel to friends/ colleagues. The recommended reading "Understanding Structural Analysis" by David Brohn is currently unavailable on amazon India. Can it be purchased in an ebook format from the publisher's website directly?
@The Structural Exam yes, that's right. I've checked that again. It's not 0 (in FEM it was very close to 0). Anyway none of the diagrams fit. The correct diagram is similar to B, but doesn't cross 0.
@@IreneuszSzum Send me your model and I will be happy to inspect - tim[a]thestructuralexam.com. I am not convinced by your explanation at all. This structure is only one degree of redundancy, so you can use the method of superposition of virtual work. Draw a bending moment without the right hand support (simple cantilever, so a triangular BM until halfway up the outside of the left column), then apply unit force to the right where the bottom right support would be and add the two solutions together. You can see the BM must cross from the inside of the structure to the outside where the fixed support is.
Maybe the following is easier. If you remove the right-hand support, then clearly, that point will move to the left. Therefore, the horizontal reaction at the roller support must be to the right.
Horizontal equilibrium means the horizontal reaction at the fixed end must be to the left.
Vertical equilibrium means no vertical reaction at the fixed support.
Sum of moments about the fixed support means the moment reaction must be anticlockwise since the only force causing moment is the applied load.
All reactions are found with certainty. Start drawing the BMD from the right support you will get case D.
Excellent explanation!
Thanks a lot. Your explanations are pretty good. But what if we are not given any options? The fact that we have two options given, and we see the point of contraflexure makes it much easier. How about we are not given any options and have no idea about the zero moment points on the left column?
Video on that coming in the next few days
Also in the meantime check this video: th-cam.com/video/RgkHKifEAQA/w-d-xo.html
Thanks
This answer seems not correct as the righthand horizontal reaction produce zero moment at left support due to zero lever arm and thus the clockwise moment due to horizontal load at left support should be balanced by the reaction moment at the left support itself . then it will a simple triangle without any contraflexure .
Thanks a lot...
Thanks for the explanation- sketching and going through the FBD at the point/s of contraflexure really helps in identifying the correct solution. I would request you to also include, if possible, the qualitative deflection diagrams in all your explanations and spend a couple of minutes on explaining the joint displacements, rotations and sway. I understand this may not be required by the problem statement, but it would really help in reinforcing our understanding of the structural behaviour.
I have subscribed to your TH-cam channel and turned on the notifications, and have been following your page on LinkedIn for the great content on structural analysis.
PS: Solving the problems along the lines of th-cam.com/video/DUJXu7APzCY/w-d-xo.html would be awesome.
PPS: Can a representative screenshot of the FBD & deflection diagrams generated in a commercially available software be also presented as a confirmation of the manually derived qualitative diagrams?
I won’t be able to do all questions due to lack of time but occasionally I suspect some of the most difficult ones will need my explanation. Thanks for the subscription! Please do tell other friends and colleagues about this channel
@@TheStructuralExam Thanks for the reply. Will surely recommend this channel to friends/ colleagues.
The recommended reading "Understanding Structural Analysis" by David Brohn is currently unavailable on amazon India. Can it be purchased in an ebook format from the publisher's website directly?
D
Hi. This is a very unintuitive example. I've checked FEM results. None of these answers is correct. Force in the right support is 0.
No, the force in the right hand support is not zero.
@The Structural Exam yes, that's right. I've checked that again. It's not 0 (in FEM it was very close to 0). Anyway none of the diagrams fit. The correct diagram is similar to B, but doesn't cross 0.
@@IreneuszSzum Send me your model and I will be happy to inspect - tim[a]thestructuralexam.com. I am not convinced by your explanation at all. This structure is only one degree of redundancy, so you can use the method of superposition of virtual work. Draw a bending moment without the right hand support (simple cantilever, so a triangular BM until halfway up the outside of the left column), then apply unit force to the right where the bottom right support would be and add the two solutions together. You can see the BM must cross from the inside of the structure to the outside where the fixed support is.
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