Thnx a lot for your comment, it does encourage me to give my best. Yep, I have added it to my list. Will do once I finish the RC series. Thnx a lot and stay tuned for more content, Regards, CEE
Thank you Thank you Sir. Everything about RSA member offset is covered in this short video.This is extremely insightful and doubts clearing. I’d probably always avoid applying offset to line and point point load and modeling an extremely short beam with a high stiffness value due to the fact that these techniques don’t reflect my structure in real life. I believe the best option is to allow RSA introduce rigid links in member offset command when analyzing the structure It’s amazing how you have soo many options at your disposal with regards to RSA software. As a practicing structural engineer, I learn a lot from your channel and always on the look out for new contents everyday. Am grateful I found your channel. Thank you CEE
Most welcome. I am glad you liked it. True, personally, I use Autodesk Robot's Member offset instead of load offset or introducing rigid members as this is how things are naturally erected in our Structures. I think RSA has rigid links but for plates and shells, I will check it out and maybe post a video about this in the future. RSA is indeed an amazing software. I personally always suggest civil engineers to use it, especially due to its compatibility with other products of Autodesk. Anyways, thanks for your comment, glad you are enjoying the videos I post. Regards, CEE
Thanks again for another great video (working my way through these chronologically on the train to work every day!) Something I found interesting in the past when I used STAAD was that it didn’t orientate angle sections and unequal angles (L sections) in the orientations they are typically used, i.e. with the outstands vertical and horizontal, but instead it orientated them with respect to their principle axes. I think robot might do it orientate to vertical by default, which should give bi-axial bending for vertical loading. Similar but different concept and maybe something to cover in a future video? Thanks again
Hi there I am really happy that you find those vids helpful. It encourages to push harder. Indeed, robot places channels on its horizontal axis instead of its principal.axis. now since those sections (especially L) are unsymmetrical, it would have consequences, exactly like you mentioned. Your suggestion to cover this is really great. I will keep it in mind once I finish the RC building series. Thnx for your comments and feedback and all the best CEE
Thanks a lot for your comment. I am happy that my vids are beneficial to you. you can support the channel by suggesting it to your friends. Regards, CEE
Yes, you could. If i understand correctly, you want to have structural elements just for the sake of "connecting elements together and distributing loads" if that is the case, you can create a section with very very small dimensions. PS: Sorry for the late reply. I had a ton of things to finish and now I am gradually getting back
This is abit of a technical question. For a frame with resisting gravity loads (DL1) as as shown in timeline 7:48 sec The major axis shear( Fz) when offseted causes a torsional moment (Mx) on the beam. And same offseted major axis shear (Fz) acts as an eccentric axial load on the columns causing minor axis bending (Mz) in the columns. How’s there Mx on columns under DL1?
I didn’t realise up until now that, under gravity loads, the shear force on the columns causes the beam with offset from the centerline , to experience out of plane (Mz) and in plane bending (My) The deflection shape is really critical to my understanding of the issues with beam offsets. I have had to watch this tutorial over again, paused to understand the technicalities with topic. It’s sooo insightful. Thank you.
I really like those technical questions, here is a quick breakdown for the reason: The frame without any offsets and with fixed supports will cause axial forces in the beam, because the supports are restraining movement in the direction parallel to the beam, which causes reactions, that are in-plane column shears (Fz) and are transferred to the beams as axial loads (Fx). Without any offsetting, the load transfer happens directly, and no moment generation is involved. With the offsets that are done in that example, suddenly the load transfer causes moments. The in-plane shear (Fz) for columns causes out of plane moments (My) on beams, because Fz is eccentrically applied, Fz has now a moment arm that causes Mx on beams. Similarly, the axial forces on beams (Fx) causes a torsional moment (Mx) on columns, because Fx is eccentrically applied to the columns. The beam (Fx) was parallel to the column cross section, but was perpendicular to the longitudinal axis of the column, thus causing Torsion instead of moments. The generated moments that are caused by forces is not always torsion nor moments, it can be either of or even both. It depends on how the offset relates the forces between the two members. Now I know it is always challenging to explain stuff like this using simple words instead of pictures and videos, but I hope it did the job. In case there is still something missing, feel free to tell me. Regards, CEE
Indeed it needs you to repeat certain positions in the video to 100% realize the relations between forces, offsets and generated moments. Glad you liked it. I always try to keep my videos concise to increase viewership and avoid boredom. Glad it worked in this video too.
as far as I know, yes. If I remember correctly, in this video, I chose to use ridiculously stiff elements to show the "behind the scenes" of it. So my guess is: yes. It would have a similar effect. I still need to verify it myself, but a quick thought about it, yes. would be similar.
@@CivilEngineeringEssentials I see, so when modeling and then analyzing it is best not to use offsets unless you know for sure there will be eccentricities. For example a simple portal frame with only gravity loads, best not to offset the top of the beam flange to the center of the column, but have them connected center-to-center
I totally agree with you, as the real force transfer will happen at the centroid of the section. I even tried that (offsetting) in a bridge girder and it did not work.
@@CivilEngineeringEssentials I am waiting for more video thank you. Can you please explain more about the buckling ratio that should be filled in the code parameters window . And how to think about it
if you mean the ratio k L / r (Note, if you mean something else, feel free to tell me the exact location in the video) here is a quick breakdown: Each axially loaded element can buckle if you are applying compression that is far more than what the element can handle. Take your plastic piece (for example), if you compress it, it will buckle. Instinctively, there are two factors affecting the buckling strength of an element. The length, which is inversely proportional, meaning a longer piece will buckle more easily than a shorter piece and second, the radius of gyration (inertia and area), meaning: a piece with a smaller cross section will buckle more easily. The third one is a bit less trivial, and has to do with the end conditions of your piece. Compression a piece between your two palms (pins, no fixation) will buckle easier than holding the two ends firm (two fixations) an compressing it. So: the longer the piece: the weaker the smaller the cross section: the weaker the weaker the end supports: the weaker kL/r measures how weak the column is. Having higher numbers means your column is weak, which would indicate potential danger and susceptibility to buckling. Thus, the ACI code defined a limit: kL/r < 22 for sway and less than 34 + some modifications for non-sway. the "k" coefficient you see there is the factor that determines how "strong" the supports. there are two axis, y and z (strong axis y and weak axis z). Thus, 2 ks. Kind Regards, CEE
@@CivilEngineeringEssentials thank you very much for your explanation. Yes these are what I meant. We should define to each member the Ky and Kz which are located in Design/steel members design - options / code parameters.
In addition to that it is difficult to define the wind load based on the ASCE code. So we will be very grateful if you can explain it and define it manually
![[SFM] Risky Recital](http://i.ytimg.com/vi/RzNkY1_Nk3o/mqdefault.jpg)
Never seen a guy like you before, thanks in advance.
I wish you could have a video on rigid links and linear releases.
Thnx a lot for your comment, it does encourage me to give my best.
Yep, I have added it to my list. Will do once I finish the RC series.
Thnx a lot and stay tuned for more content,
Regards,
CEE
Thank you Thank you Sir.
Everything about RSA member offset is covered in this short video.This is extremely insightful and doubts clearing.
I’d probably always avoid applying offset to line and point point load and modeling an extremely short beam with a high stiffness value due to the fact that these techniques don’t reflect my structure in real life.
I believe the best option is to allow RSA introduce rigid links in member offset command when analyzing the structure
It’s amazing how you have soo many options at your disposal with regards to RSA software. As a practicing structural engineer, I learn a lot from your channel and always on the look out for new contents everyday.
Am grateful I found your channel.
Thank you CEE
Most welcome. I am glad you liked it.
True, personally, I use Autodesk Robot's Member offset instead of load offset or introducing rigid members as this is how things are naturally erected in our Structures.
I think RSA has rigid links but for plates and shells, I will check it out and maybe post a video about this in the future.
RSA is indeed an amazing software. I personally always suggest civil engineers to use it, especially due to its compatibility with other products of Autodesk.
Anyways, thanks for your comment, glad you are enjoying the videos I post.
Regards,
CEE
Thanks again for another great video (working my way through these chronologically on the train to work every day!)
Something I found interesting in the past when I used STAAD was that it didn’t orientate angle sections and unequal angles (L sections) in the orientations they are typically used, i.e. with the outstands vertical and horizontal, but instead it orientated them with respect to their principle axes.
I think robot might do it orientate to vertical by default, which should give bi-axial bending for vertical loading. Similar but different concept and maybe something to cover in a future video? Thanks again
Hi there
I am really happy that you find those vids helpful. It encourages to push harder.
Indeed, robot places channels on its horizontal axis instead of its principal.axis. now since those sections (especially L) are unsymmetrical, it would have consequences, exactly like you mentioned. Your suggestion to cover this is really great. I will keep it in mind once I finish the RC building series.
Thnx for your comments and feedback and all the best
CEE
Thank you so much this was really helpful, Appreciations to your efforts.
Most welcome. Happy it helped. Stay tuned for more content.👍
Man you are really amazing, thank you for your efforts.
Glad you liked it. Consider suggesting the channel to your friends, it helps a lot.
Regards,
CEE
Thank you, great content! I'm very happy I found your chanel!
Thanks a lot for your comment. I am happy that my vids are beneficial to you. you can support the channel by suggesting it to your friends.
Regards,
CEE
Thank you! Great explanation 👏
Happy you liked it and welcome aboard
Stay tuned for more content and maybe share this channel 🌹👍
sir is there any way u can make a dummy frame/beam in RSA? for adding distribution moment that is not laying on a beam
Yes, you could. If i understand correctly, you want to have structural elements just for the sake of "connecting elements together and distributing loads"
if that is the case, you can create a section with very very small dimensions.
PS: Sorry for the late reply. I had a ton of things to finish and now I am gradually getting back
This is abit of a technical question.
For a frame with resisting gravity loads (DL1) as as shown in timeline 7:48 sec
The major axis shear( Fz) when offseted causes a torsional moment (Mx) on the beam. And same offseted major axis shear (Fz) acts as an eccentric axial load on the columns causing minor axis bending (Mz) in the columns.
How’s there Mx on columns under DL1?
I didn’t realise up until now that, under gravity loads, the shear force on the columns causes the beam with offset from the centerline , to experience out of plane (Mz) and in plane bending (My)
The deflection shape is really critical to my understanding of the issues with beam offsets.
I have had to watch this tutorial over again, paused to understand the technicalities with topic. It’s sooo insightful.
Thank you.
I really like those technical questions, here is a quick breakdown for the reason:
The frame without any offsets and with fixed supports will cause axial forces in the beam, because the supports are restraining movement in the direction parallel to the beam, which causes reactions, that are in-plane column shears (Fz) and are transferred to the beams as axial loads (Fx).
Without any offsetting, the load transfer happens directly, and no moment generation is involved.
With the offsets that are done in that example, suddenly the load transfer causes moments.
The in-plane shear (Fz) for columns causes out of plane moments (My) on beams, because Fz is eccentrically applied, Fz has now a moment arm that causes Mx on beams.
Similarly, the axial forces on beams (Fx) causes a torsional moment (Mx) on columns, because Fx is eccentrically applied to the columns. The beam (Fx) was parallel to the column cross section, but was perpendicular to the longitudinal axis of the column, thus causing Torsion instead of moments.
The generated moments that are caused by forces is not always torsion nor moments, it can be either of or even both. It depends on how the offset relates the forces between the two members.
Now I know it is always challenging to explain stuff like this using simple words instead of pictures and videos, but I hope it did the job. In case there is still something missing, feel free to tell me.
Regards,
CEE
Indeed it needs you to repeat certain positions in the video to 100% realize the relations between forces, offsets and generated moments. Glad you liked it.
I always try to keep my videos concise to increase viewership and avoid boredom. Glad it worked in this video too.
Great video!
thnx a lot. I am happy you liked it.
If possible, please suggest this channel to your friends. It helps a lot.
Regards,
CEE
If I use rigid links, will it have the same effect as offsets?
as far as I know, yes. If I remember correctly, in this video, I chose to use ridiculously stiff elements to show the "behind the scenes" of it.
So my guess is: yes. It would have a similar effect. I still need to verify it myself, but a quick thought about it, yes. would be similar.
how will offsetting a beam top flange to the column change the results?
because the axial forces in the direction of the original beam would have moments when the beam gets offsetted. (kind of like an eccentricity).
@@CivilEngineeringEssentials I see, so when modeling and then analyzing it is best not to use offsets unless you know for sure there will be eccentricities.
For example a simple portal frame with only gravity loads, best not to offset the top of the beam flange to the center of the column, but have them connected center-to-center
I totally agree with you, as the real force transfer will happen at the centroid of the section.
I even tried that (offsetting) in a bridge girder and it did not work.
You are the best 💞😘
Glad you liked it. Stay tuned for more videos.
@@CivilEngineeringEssentials I am waiting for more video thank you. Can you please explain more about the buckling ratio that should be filled in the code parameters window . And how to think about it
if you mean the ratio k L / r
(Note, if you mean something else, feel free to tell me the exact location in the video)
here is a quick breakdown:
Each axially loaded element can buckle if you are applying compression that is far more than what the element can handle. Take your plastic piece (for example), if you compress it, it will buckle.
Instinctively, there are two factors affecting the buckling strength of an element.
The length, which is inversely proportional, meaning a longer piece will buckle more easily than a shorter piece
and second, the radius of gyration (inertia and area), meaning: a piece with a smaller cross section will buckle more easily.
The third one is a bit less trivial, and has to do with the end conditions of your piece.
Compression a piece between your two palms (pins, no fixation) will buckle easier than holding the two ends firm (two fixations) an compressing it.
So:
the longer the piece: the weaker
the smaller the cross section: the weaker
the weaker the end supports: the weaker
kL/r measures how weak the column is. Having higher numbers means your column is weak, which would indicate potential danger and susceptibility to buckling.
Thus, the ACI code defined a limit: kL/r < 22 for sway and less than 34 + some modifications for non-sway.
the "k" coefficient you see there is the factor that determines how "strong" the supports.
there are two axis, y and z (strong axis y and weak axis z). Thus, 2 ks.
Kind Regards,
CEE
@@CivilEngineeringEssentials thank you very much for your explanation. Yes these are what I meant. We should define to each member the Ky and Kz which are located in Design/steel members design - options / code parameters.
In addition to that it is difficult to define the wind load based on the ASCE code. So we will be very grateful if you can explain it and define it manually
Any e-mail for contacts? thank for your nice tutorial
you are welcome.
The email is:
civ.eng.essentials@gmail.com