Hello CEE, 03:42 Congratulations are in order on the current subscribers milestone. You really deserve it and much much much more. In my opinion, the CEE channel remains a shining beacon of excellence with exemplary content and with real active and open dialogue, both of which I am grateful for and I am still in awe of. The idea of a multi-parted slabs series with each part dealing with a slab and the nuances and the “nice stuffs” relating to that kind or type of slab is a great idea and I am looking forward to this planned series parts. Great introduction on the main various types of the slabs that are available, and a very nice way to kick-off the series with “Flat slabs without the drop panels”. 02:52 LOL Mr. Editor, good catch, I was not thinking much about the design codes, I was thinking of the stated “consequence” of having to deal with beam shear stirrups as opposed to slab punching shear. It is good to have you around and keeping wondering minds like mine in check! I know that this particular video part is discussing “a flat slab beamless”; but seeing though that this other issue was brought-up and touched upon on this video, and with reference to the implications explained on one of the previous video regarding the “importance of beam stiffness”; I am curious about how one would have to model (in RSAP) the mentioned beams that are inside the slab, considering that these beams would essentially be having the same stiffness as the rest of the slab? In theory, RSAP should not even know or “see” 😊 those beams and as such the resulting distribution of the internal forces would not be affected…..how then would one have to model the beams in question in order for RSAP to “see” them and to accordingly distribute most of the internal forces to them beams? 05:17 & 05:27 w.r.t Stiffness reduction coefficients. I have read your explained response to subscriber Michael Loreantz regarding a similar question from an earlier video (learning basics of plates and shells), thanks for that response and thanks to Michael for asking that question. The current referenced RFEM dlubal website is nice. For the slabs, it seems that in the majority of the cases, one could simply input a single value for the moment of inertia (flexural stiffness) reduction factor under the “homogeneous” slab thickness definition. Could you perhaps consider to later dive in and illustrate under which (or if) there are practical applications and cases where one would need to use “orthotropic” slab thickness definitions for implementing stiffness reduction coefficients? 10:29 “…so far this should be boring…..”, this statement gets me every time 😂🤣😂 16:33 w.r.t ETABS tutorials; my take is that if there are strong areas in which ETABS excels in and if there are types of structures or structural components which CEE consider that the subscribers would benefit by say running and comparing the outputs from both software (ETABS and RSAP) side-by-side. In that case, I don’t see why not introduce ETABS to the channel content as may be required. If, however there are no pronounced differences or specific areas of added value compared to RSAP, my views are then to keep focus and to narrow the scope in favour of more “projects” structures and structural elements or components series. This is my opinion (I guess democracy (or not) shall have the final say??). 17:42 Nope, not angry at all, I am just that much more curious in anticipation of what is yet to come…. 20:17 In the “Limit States” section of the “Slab and Shell Reinforcement” dialog box, I think it is important to also change or to choose the “Method” from “analytical” to “equivalent mom. (wood&Amor)” as a way to “tell” RSAP to calculate and design the slab reinforcements using the wood and amour equivalent moments as opposed to using the analytical moments results? 21:52 Under SLS tab. What does the “Stiffness factor” results (values) signify? For X_bottom, X_top, Y_bottom, Y_top. What would one read these values to mean for the slab reinforcements in various directions and layers in simplified “Layman_ish” terms? I know 😊, but I must ask to be sure: The Deflection u, I am assuming this is the elastic-short term deflection? I take note of the SLS parameters setting and definitions under the “Slab and Shell Reinforcement Type” definition dialog (24:45). What I am missing is that: after doing the settings and running the calculations, where (in RSAP) do I now go to view the resulting long-term deflections for this slab? 24:09 Mr. Editor, Radial direction main reinforcements are screaming to be put on the “Current Video Ideas for the Future list”. From Mr. Recorder explanations, 😊 I am thinking maybe to be considered in future with possible design of a RC circular dome roof or cover slab for a circular water tank or for other similar round structure? 26:29 I concur with Mr. Editor, also since this is “required reinforcement”, the area of reinforcement “required” should be the same irrespective of the sizes of rebars that are set or are selected or chosen in the “Slab and Shell Reinforcement Type” definition dialog box. And yes, the sizes of rebars set should affect the “spacing e” and “the number of bars n”. 27:54 YES, Pls. 34:00 I am also a fan of closer spacings of rebars and at the same time the fewer (least) number of different spacings the better. The CEE shared personal preference of spacing not more than the depth of the slab is a very good starting reference point [and then there are design codes limits of course]. Chat WHAT??? 🤨, I guess that “Skynet” figured that if it does not change its name to something else, everyone will see it coming…..Hasta la vista….to life as we now know it. 36:16 Yes, I think Mr. Recorder thoughts in this video are fruitful. Reality is reality; unfortunately, it is often too easy for some designers to forget that the software is a tool and the designer must look at reality and incorporate that reality into the final solutions that the designer provides to the construction team so that those solutions also reflect practical and doable work. Mr. Recorder thoughts in this video are keeping that part in check for the designer (in my opinion). Thank you for the video, and I am looking forward to the next one. Regards, DK Ps: I don’t know if it is just me, but the sound quality of this video tutorial seem to have an echoed or a small enclosed space feel, nonetheless it is still audible.
Hi there Engr. DK, Happy you also like this series, I am trying to cover most parts of a "bigger multi-story building" so that I do not need to explain basics again when I reach that moment. Also, I am thrilled by the speed at which this community has grown. It started in August with 0 subscribers. Wondering minds are always a great thing, but as you correctly stated, balance is needed. For beams in flat slabs, there is something incorrect we do when we design that stuff, i.e. we assume the flat slabs to be 100% carried by the beams, this is - of course - plain wrong in my humble opinion, as it is the slab that is as "strong" as the beam. Now this is different in a ribbed slab with beams, and I would mention this - if I remember - in that video when I reach it. Still, the reason why one would model a beam in the slab is the case when you really really need one to resist punching shear, and the idea of having column caps seems to be impractical. Now truth to be said, I have no scenario where a column cap would not solve the issue or is impractical, but well, maybe there exists a case so I want to just give this info to whoever is intereted. Indeed I had an interesting discussion with Engr. Loreantz about that. Now in that discussion I did not want to point out a "lazy get out of jail free card" to say: yeah it is the code. There, I actually explained it in detail. However, in this video, and because I am targeting the general audience who comes from code backgrounds, I did abide by the code. I still concede that I failed/forgot to mention the detailed discussion during my recording, also Mr. Editor seems to have done a sloppy job (I am totally getting burned by him next time for this, for sure ^_^) in case of homogeneous stiffness reduction, this would be for solid slabs of constant thickness. For orthotropic slabs, the short answer is: the direction of max inertia. The long answer is: in orthotropic slabs, your main load carrying element in that slab are the elements of higher inertia, as you may know: the amount of generated bending moment is proportional to the stiffness of the beam, so those stiffer elements would do the loading, and they would ultimately crack first, waaaay ahead before the other direction cracks. So I would use the reduction only for the stronger direction. With that being said, I still have in mind that the seconday direction does have minimum steel, and may even have significant moments if the inertia difference between strong and weak is not that big, so it ultimately gets back to my judgement. I guess my statements of boredom are basically on point ^_^. Actually, I do say this when I personally feel it. ETABS, as far as I know, has 1 clear advantage to RSA, which is its wind load calculation. In ETABS, an "invisible" cladding is generated around the structure and pressures are applied based on code calculations. Of course, the claddings are not visible, and only due to careful consideration can the effect be detected and their exitence be deduced. About the meshing, I actually had your request in mind. While I was doing my work, I felt that it is somehow a little empty. I mean, the viewer wants to see how "to use" the tool, but I also want to intrigue users by understanding "why" this thing works. So I felt it was not really enough. Oh my!! Yes, I missed to change the reinforcement calculation theory! I took a lot of time explaining yet, and yet I missed using it. This part of the comment is gonna get cut and paste into the video details so all ppl get to see it. About the SLS, The Editor has actually cut it out as it was not clear in explanation, I will explain it next video. Deflection u is elastic short term, I have to double check that, coz there was a way back in my days to see the long term deflections. I do not have robot with me at the moment, but the easiest way of double checking u is to go the the "geometry" GUI and go to maps -> uz and compare. if they are the same, it is short term. I'll tell Mr. Editor about radial reinforcements. It is kind of cool and has limited, yet really intriguing applications. Now I remember once trying to reinforce a circular dome with it, but robot struggles to detail 3D structures in space. I'll keep that tabbed. Punching shear is gonna be defintely featured in the next video. Also, I WILL BE BACK with more videos of course, also also, nobody talks about "Genisys", and for good reasons I guess ^_^ I worked with teams in normal structures before where they are just "muscles". About the sound quality, yes indeed, I recorded without my usual microphone. I used the laptop mic which is much worse. But now things are back to normal. Anyways, it is always interesting to read your comment, stay tuned for more stuff ^_^ Regards, CEE
@@CivilEngineeringEssentials Thank you for the feedback, there is much insight on the various matters that have been addressed in your feedback. @CEE, you are doing a wonderful job. Do not stress if you miss little things here and there. w.r.t the “wood&Amor” moments I am able to recognise this because of YOU, I am proverbially standing on your shoulders. Without your clear explanations, many things would still be hanging in doubt for me. Be proud, because your wisdom is being well received. Regards, DK
I have finally catched up on your videos, and look forward to following your videos as they are posted! I dont expect you to answer the questions below, but if you have the time, I would appreciate your thoughts on the following: I am really interested in the technical insight you present, and look forward to more info about the meshing. I guess subjects as shear locking, hour glass modes etc. are not super relevant, as Robot only presents elements which are not vulnerable for such? Anyway, it would be great to hear more about the elements they do present, I remember you talked about a discrete Kirchoff-Mindlin element (or something:D). I know that ideally, the elements should have as little distortion as possible, and optimal meshes should have as straight and even angles and side-length ratios as possible. What are your thoughts on this, taken the elemenet-types Robot present into consideration? I have also wondered about another topic - concrete stiffness in Robot. I was doing a simple experiment with a cantilever, rectangular beam, and it showed that the stiffness simply was E*bh^3/12 (EI) - like as the concrete have the same properties in tension as in compression. However, the stiffness of concrete is quite complex(cracked, non-cracked, reinforcement-ratio and so on). Do you have any thoughts on this, and how to represent this numerically in Robot? I remember you talked about stiffness ratios between carrying beams and slabs in the pedestrian bridge series. In this case, this issue is highly relevant. A final thought about this (sorry for overloading), is how relative stiffness will affect a floor in a floor-ground interaction. Would you agree that a super stiff ground(This is probably never the case, but in a theoretical point of view) would make you treat the floor as a strut and tie-model - that is, distributing the loads at an 45deg angle or something down to the ground giving you a very limited load area on the ground, while a relatively soft ground would let you treat the floor as an upside-down slab, with the point loads as the columns, and the counter pressure from the ground as a distributed load? I would finally just let you know that I am exited for the dynamics you will present(loved the prev. vids about this), as you are an expert on the field (and i am very much not). It would be very insightful to see how theory fits the FE dynamic results. Could you for example compare dynamic results from Robot in a simple beam or frame with some relatable hand calculations? If I do remember correctly, we assume certain deflection modes as chosen functions, like ø(x)=sine(n*pi*x/L), n being the mode number, and then use this to find the frequency. Demonstrating something like this (and other solution methods) would be perfect. Thank you for your videos!
Hi there, Happy you liked those As a matter of fact, I do read all comments and answer most of the questions. So here you go: About Meshing, this is the topic of the video: The Slab Series | Part 3, so you can expect it soon (I am preparing Part 2 at the moment) I will add those technical details about meshing such as shear locking into my account. I will try to find a simplified way and strike a balance between a "general purpose video" and "some insights for the more technically interested people". Indeed, you are right about the "distrotions" of the elements. Now to give you some food for thought, the elements you see here are actually transferred into an "alternate reality" called the isoparametric element. The element is mapped onto that isoparametric member. Now the more distortions you have in the original member, the more the "mapper" has problems in mapping your element to its "alternate reality sibling". Now the technical terms involved are: isoparametric formulation, jacobi matrix, determinant of jacobi matrix. I do not think I would go into such detail in the mesh video, but I still have the scientific obligation to tell you about these things. Now those shortcomings can be remedied by decreasing element sizes, but of course, this comes at increased calculation cost. Yes
Great video Sir. Very detailed and full of useful knowledge. This is a good video to celebrate your milestone of 1000 subscribers. Continue the good work.
Hello there Engr. Nii, thnx a lot ^_^ it is just a part of a multi-parter about slabs, stay tuned for more content. Also, thnx a lot for being around all that time, I wish you all the best. Regards, CEE
32:45 Robot missed an opportunity here to add hook settings for up / lower reinforcement separately 33:59 You argued you are >personally < against big spacing. But isn't it generally correct to maintain a short spacing, in order to have a good reinforcement aka more homogeneous? Cracked slabs come to mind 😬
I agree totally, it is generally good to maintain smaller spacing. But it is not all black and white, You see, the codes give "min" and "max" values, and it is kind of a spectrum in between. Go towards the min, and you are going to suffer in concrete placing (coz some people forget that there is other steel to be considered in a slab such as the column steel) Go too far, and you are risking cracking. Anyways,
Nice video, thank you effort if you could please do another video about basement wall, because when I try to calculate the column in the basement there is no continuity of the load from the above stories .
@@CivilEngineeringEssentials Thank you for answering, problem solved ^^'. Do you have any video related to design of dynamic loads such as movement of car/lorries on a road ? Do you know if there is a way to check the fatigue in robot for dynamic loads ?
Good day CEE, I trust that you are well. This comment is with regards to the meshing of the current slab. I have just observed that if one uses a “coarse” mesh, the results of reinforcements distribution (even the results of the slab bending moments Maps) are not wholly symmetrical as one would have expected them to be? However, if one changes the mesh to either “normal” or “fine”, then the results become symmetrical (as expected) and within the bounds of the slab geometrical dimensions and configuration of course. Now I appreciate that a “coarse” mesh will not give same “smooth” results as say a “fine” mesh. I had thought (I mean, I assumed without an actual referable basis, shame on me ☹😞) that the “coarse” mesh, as “rough” as it may be, it will be “equally and symmetrically” rough on both opposite sides that are expected to behave symmetrically. Clearly this is not the case. What concerns me about this is as follows: • Does this now mean that a “rough” mesh can create “non-existing” imbalances on two opposite sided that are otherwise geometrically symmetric and even loaded symmetrically? • If so, how then should designers trust the analysis results of a multi-storey structure with appreciable amounts of slab elements when the structure as a whole is analysed using “coarse” mesh settings? Would the “imbalances” if they exist not “distort” the true-er behaviour of the structure? • Is it advisable to run analysis with only “normal” or “fine” mesh settings? Perhaps some of what I mentioned is something CEE is still to cover in the planned meshing video? If so, I can get clarity when that video is released. Keep well, DK
Hi there, Engr. DK If you are using coarse mesh, the FEM mesh is not double axis symmetric (x symmetry and y symmetry), thus there is a slight stiffness difference which causes the unsymmetric moment diagram and thus the reinforcement. Yes, a coarse mesh creates imbalances, I will address this in my next video which is all about meshing. Actually, the reactions of the identical columns would not be identical. Edge columns will have different reactions. Secondly, indeed, due to this slight problem in the mesh, your multi-story structure will create "twisting motions" even if it is 100% double symmetric. This is something that all my graduate students face and ask me about. I will definitely talk about this in my full structure series. There is some really juicy content to talk about. (Gonna tell editor to add this point to the list. For me, it is actually advisable to run coarse mesh settings for "quick structural checks" and fine settings when you are getting "serious" and want to export designs. Of course, this will be covered in my mesh video next time. The mesh video should be released next Friday (hopefully). Regards, CEE
@@CivilEngineeringEssentials Thank you so much for this feedback. It is now even clearer to me that without understanding the FE method, one could do some serious damage with it. The CEE community is fortunate to have you who clearly understands well how the FE method works You are amongst the rarest of the best. Keep well. DK
Hi, I am structural Engineer in Germany. Curently working with Dlubal RFEM, Infograph InfoCAD, MB Aec, Nemetschek Frilo. I am concidering to by Robot Structural Software to do some Projekts in UAE and in Poland. Then I would use Robot also for some Projekts in Germany. My Question to you is it possible to calculate a flat slab and automaticaly take the seactons as Load for the slab below? I know you can do i ti in 3D but for some specific Projekts in Germany 3D Static is not allowed. With Rfem and InfoCAD, also with MB and Frilo i can take Reactions as loads but I am not sure if Robot can do it? I would be thankfull for your answer.
Halli Hallo, toll mal auf deutsch sprechen zu koennen. Ich habe Sie leider nicht 100% verstanden. Sie meinen, dass Sie in 3D modelieren wollen und die Auflagerkraefte (mein Keyboard hat keine Umlaute) zu exportieren? Das geht einfach: Menu: Results -> Reactions Im Fall das Sie etwas anderes meinten, koennen Sie gerne hier 'ne Antwort schreiben. Immer Gerne, CEE
@@CivilEngineeringEssentials Hi, ich wusste nicht dass Sie Deutsch sprechen. In Deutschland macht Mann fast immer so genannte Positionsstatik. Das bedeutet alle statische Positionen werden separat statisch betrachtet und gerechnet. In dem Fall rechne ich eine Decke zum Bsp. Decke über 1.OG als 2D Decke/Platte und übernehme ich die Auflagerkräfte dieser Decke als weitere Belastung für die untere Decke (In dem Fall Decke über EG oder für die Bodenplatte). Ich weiß nicht ob Mann Auflagerkräfte eines Modells als Belastung für ein anderen Modell in Robot übernehmen kann? 3D Statik ist in Deutschland nicht immer zugelassen und auch nicht immer prüffähig. Robot kostet schon was und wenn ich den Programm kaufe dann würde ich Robot auch für weitere Projekte in Deutschland nutzen. Aus dem Grund ist diese Frage für mich sehr wichtig. Vielen Dank! Mit freundlichen Grüßen Dipl.-Ing. Kemal Halitovic Bauingenieur mail@ing-halitovic.de Statik / Konstruktion / Brandschutz / Schallschutz / Wärmeschutz
@@CivilEngineeringEssentials Hallo, ich wusste nicht dass Sie Deutsch sprechen. Meine Frage ist ob in Robot möglich ist Auflagerkräfte eines Modelles als Belastung für ein anderen Modell zu übernehmen? In Deutschland ist leider nicht immer erlaubt eine 3D Statik zu erstellen. Sondern wir machen hier fast immer so gennannte Positionsstatik. Bei dieser Statik werden alle Positionen einzeln statisch betrachtet und gerechnet. In dem Fall rechne ich die Decke über z.Bsp. über 1.OG als 2D Decke, dann übernehme ich Auflagerkräfte dieser Decke als Belastung für die Decke über EG. Das ermöglicht sehr genaue statische Analyse und einzelne Nachweise sowie eine sehr saubere Dokumentation und klare Lastweiterleitung. In Rfem und MB, InfoCAD und Frilo z. Bsp. ist sehr einfach die Auflagerkräfte eines Modells al Belastung für ein anderen Modell zu übernehmen. Kann mann sowas auch mit dem Robot machen und wenn ja wie kann ich dass machen? Falls dass ich den Robot kaufe würde ich den Programm gerne auch für die Projekte in Deutschland nutzen aus dem Grund ist diese Frage für mich sehr wichtig. Vielen Dank im Voraus. Dipl. -Ing. Kemal Halitovic mail@ing-halitovic.de
@@Guru_091Gru Oh, jetzt versteh ich wass Sie meinen. Genau, in DE kann mann nur einzelnachweise fuehren (z.B. Harzer Statik) So einfach ist es nicht, die auflagerkraefte auf nen anderen Model zu uebernehmen. Mann koennte zwar die Auflagerkraefte von (Results -> Reactions) anschauen, aber die einfach weiterzuleiten geht leider nicht. Es waere zwar moeglich, es nach Excel zu exportieren und irgendwie diese zu importieren, aber das ist nicht die haufen tausend Euro fuer Robot wert. Sorry dass es laenger gedauert hat, zu antworten. Viel Erfolg und MfG, CEE
Hi there CEE. I am really enjoying your videos. I´d like to know if its possbile to run a plastic (i´m not sure that´s the correct word in english) analysis for slabs (shells). In other words, i´m not confortable with some results i´m getting of a particular RC structure that i´m looking at, it seems too stiff. In my country, for shells, our code allows to simulate plastic pinns located on the critical sections through a non-linear analysis, and establishes a limit for rotation of tha pinn in miliradians due to a moment/shear ratio, section geometry and ductility parameters. That allows to redistribute moments along the structure. Is there a way to simulate this kind of behavior on Robot?
Hi there Engr. Vitor, I am happy you find the content of this channel beneficial. It help if you want to suggest it to your friends. About non-linear hinges for plates, I have to check if there is something like this in robot. I would make a video about it if I find it ^_^ Anyways, stay tuned for more content. Regards, CEE
Always have problems with slabs result in RSA😅, don't understand the result for required Reinforcement X-,X+,Y- and Y+. Even Mx,My, Mxy Not talking about provided Reinforcement, the results of numbers and colours(orange&blue on the slab) totally lost!😅
Actually, there are four of us running around (Recorder N00b, Witty Editor, Subordinate Teaching Assistant and the Dr. himself). There is another guy in the shadows, he was mentioned only once in 1 video. Oh also, usually it is the editor personality who is responding the comments. While loving to roast his recorder n00by, he is actually quite nice to his viewers and subscribers. LOL, not gonna video edit it neither. Stay tuned for more content. CEE
Quite the setup 😆 I missed the "other guy", but for the 4, I can actually identify them. FYI I find myself pausing the video for reading your comments over the recorder voice and the YT controls overlap - I wouldn't recommend reducing the recording size for the sake of clear comments, cause it's still readable, but I thought it's something you should know.
@@razvanmure that is a great piece of advice. So, it seems to be the "positioning" that might be a tad off. I see. I think I do have some space on the top, so I might push the recording further upward and try keep my comments up a little bit. Makes sense to me. Thnx a lot ^_^
Hello CEE,
03:42 Congratulations are in order on the current subscribers milestone. You really deserve it and much much much more. In my opinion, the CEE channel remains a shining beacon of excellence with exemplary content and with real active and open dialogue, both of which I am grateful for and I am still in awe of.
The idea of a multi-parted slabs series with each part dealing with a slab and the nuances and the “nice stuffs” relating to that kind or type of slab is a great idea and I am looking forward to this planned series parts.
Great introduction on the main various types of the slabs that are available, and a very nice way to kick-off the series with “Flat slabs without the drop panels”.
02:52 LOL Mr. Editor, good catch, I was not thinking much about the design codes, I was thinking of the stated “consequence” of having to deal with beam shear stirrups as opposed to slab punching shear. It is good to have you around and keeping wondering minds like mine in check!
I know that this particular video part is discussing “a flat slab beamless”; but seeing though that this other issue was brought-up and touched upon on this video, and with reference to the implications explained on one of the previous video regarding the “importance of beam stiffness”; I am curious about how one would have to model (in RSAP) the mentioned beams that are inside the slab, considering that these beams would essentially be having the same stiffness as the rest of the slab? In theory, RSAP should not even know or “see” 😊 those beams and as such the resulting distribution of the internal forces would not be affected…..how then would one have to model the beams in question in order for RSAP to “see” them and to accordingly distribute most of the internal forces to them beams?
05:17 & 05:27 w.r.t Stiffness reduction coefficients. I have read your explained response to subscriber Michael Loreantz regarding a similar question from an earlier video (learning basics of plates and shells), thanks for that response and thanks to Michael for asking that question. The current referenced RFEM dlubal website is nice. For the slabs, it seems that in the majority of the cases, one could simply input a single value for the moment of inertia (flexural stiffness) reduction factor under the “homogeneous” slab thickness definition. Could you perhaps consider to later dive in and illustrate under which (or if) there are practical applications and cases where one would need to use “orthotropic” slab thickness definitions for implementing stiffness reduction coefficients?
10:29 “…so far this should be boring…..”, this statement gets me every time 😂🤣😂
16:33 w.r.t ETABS tutorials; my take is that if there are strong areas in which ETABS excels in and if there are types of structures or structural components which CEE consider that the subscribers would benefit by say running and comparing the outputs from both software (ETABS and RSAP) side-by-side. In that case, I don’t see why not introduce ETABS to the channel content as may be required. If, however there are no pronounced differences or specific areas of added value compared to RSAP, my views are then to keep focus and to narrow the scope in favour of more “projects” structures and structural elements or components series. This is my opinion (I guess democracy (or not) shall have the final say??).
17:42 Nope, not angry at all, I am just that much more curious in anticipation of what is yet to come….
20:17 In the “Limit States” section of the “Slab and Shell Reinforcement” dialog box, I think it is important to also change or to choose the “Method” from “analytical” to “equivalent mom. (wood&Amor)” as a way to “tell” RSAP to calculate and design the slab reinforcements using the wood and amour equivalent moments as opposed to using the analytical moments results?
21:52 Under SLS tab. What does the “Stiffness factor” results (values) signify? For X_bottom, X_top, Y_bottom, Y_top. What would one read these values to mean for the slab reinforcements in various directions and layers in simplified “Layman_ish” terms?
I know 😊, but I must ask to be sure: The Deflection u, I am assuming this is the elastic-short term deflection? I take note of the SLS parameters setting and definitions under the “Slab and Shell Reinforcement Type” definition dialog (24:45). What I am missing is that: after doing the settings and running the calculations, where (in RSAP) do I now go to view the resulting long-term deflections for this slab?
24:09 Mr. Editor, Radial direction main reinforcements are screaming to be put on the “Current Video Ideas for the Future list”. From Mr. Recorder explanations, 😊 I am thinking maybe to be considered in future with possible design of a RC circular dome roof or cover slab for a circular water tank or for other similar round structure?
26:29 I concur with Mr. Editor, also since this is “required reinforcement”, the area of reinforcement “required” should be the same irrespective of the sizes of rebars that are set or are selected or chosen in the “Slab and Shell Reinforcement Type” definition dialog box. And yes, the sizes of rebars set should affect the “spacing e” and “the number of bars n”.
27:54 YES, Pls.
34:00 I am also a fan of closer spacings of rebars and at the same time the fewer (least) number of different spacings the better. The CEE shared personal preference of spacing not more than the depth of the slab is a very good starting reference point [and then there are design codes limits of course].
Chat WHAT??? 🤨, I guess that “Skynet” figured that if it does not change its name to something else, everyone will see it coming…..Hasta la vista….to life as we now know it.
36:16 Yes, I think Mr. Recorder thoughts in this video are fruitful. Reality is reality; unfortunately, it is often too easy for some designers to forget that the software is a tool and the designer must look at reality and incorporate that reality into the final solutions that the designer provides to the construction team so that those solutions also reflect practical and doable work. Mr. Recorder thoughts in this video are keeping that part in check for the designer (in my opinion).
Thank you for the video, and I am looking forward to the next one.
Regards, DK
Ps: I don’t know if it is just me, but the sound quality of this video tutorial seem to have an echoed or a small enclosed space feel, nonetheless it is still audible.
Hi there Engr. DK,
Happy you also like this series, I am trying to cover most parts of a "bigger multi-story building" so that I do not need to explain basics again when I reach that moment.
Also, I am thrilled by the speed at which this community has grown. It started in August with 0 subscribers.
Wondering minds are always a great thing, but as you correctly stated, balance is needed.
For beams in flat slabs, there is something incorrect we do when we design that stuff, i.e. we assume the flat slabs to be 100% carried by the beams, this is - of course - plain wrong in my humble opinion, as it is the slab that is as "strong" as the beam.
Now this is different in a ribbed slab with beams, and I would mention this - if I remember - in that video when I reach it. Still, the reason why one would model a beam in the slab is the case when you really really need one to resist punching shear, and the idea of having column caps seems to be impractical. Now truth to be said, I have no scenario where a column cap would not solve the issue or is impractical, but well, maybe there exists a case so I want to just give this info to whoever is intereted.
Indeed I had an interesting discussion with Engr. Loreantz about that. Now in that discussion I did not want to point out a "lazy get out of jail free card" to say: yeah it is the code. There, I actually explained it in detail. However, in this video, and because I am targeting the general audience who comes from code backgrounds, I did abide by the code.
I still concede that I failed/forgot to mention the detailed discussion during my recording, also Mr. Editor seems to have done a sloppy job (I am totally getting burned by him next time for this, for sure ^_^)
in case of homogeneous stiffness reduction, this would be for solid slabs of constant thickness.
For orthotropic slabs, the short answer is: the direction of max inertia.
The long answer is: in orthotropic slabs, your main load carrying element in that slab are the elements of higher inertia, as you may know: the amount of generated bending moment is proportional to the stiffness of the beam, so those stiffer elements would do the loading, and they would ultimately crack first, waaaay ahead before the other direction cracks. So I would use the reduction only for the stronger direction. With that being said, I still have in mind that the seconday direction does have minimum steel, and may even have significant moments if the inertia difference between strong and weak is not that big, so it ultimately gets back to my judgement.
I guess my statements of boredom are basically on point ^_^. Actually, I do say this when I personally feel it.
ETABS, as far as I know, has 1 clear advantage to RSA, which is its wind load calculation. In ETABS, an "invisible" cladding is generated around the structure and pressures are applied based on code calculations.
Of course, the claddings are not visible, and only due to careful consideration can the effect be detected and their exitence be deduced.
About the meshing, I actually had your request in mind. While I was doing my work, I felt that it is somehow a little empty. I mean, the viewer wants to see how "to use" the tool, but I also want to intrigue users by understanding "why" this thing works. So I felt it was not really enough.
Oh my!! Yes, I missed to change the reinforcement calculation theory! I took a lot of time explaining yet, and yet I missed using it. This part of the comment is gonna get cut and paste into the video details so all ppl get to see it.
About the SLS, The Editor has actually cut it out as it was not clear in explanation, I will explain it next video.
Deflection u is elastic short term, I have to double check that, coz there was a way back in my days to see the long term deflections. I do not have robot with me at the moment, but the easiest way of double checking u is to go the the "geometry" GUI and go to maps -> uz and compare. if they are the same, it is short term.
I'll tell Mr. Editor about radial reinforcements. It is kind of cool and has limited, yet really intriguing applications. Now I remember once trying to reinforce a circular dome with it, but robot struggles to detail 3D structures in space. I'll keep that tabbed.
Punching shear is gonna be defintely featured in the next video.
Also, I WILL BE BACK with more videos of course, also also, nobody talks about "Genisys", and for good reasons I guess ^_^
I worked with teams in normal structures before where they are just "muscles".
About the sound quality, yes indeed, I recorded without my usual microphone. I used the laptop mic which is much worse. But now things are back to normal.
Anyways, it is always interesting to read your comment, stay tuned for more stuff ^_^
Regards,
CEE
@@CivilEngineeringEssentials
Thank you for the feedback, there is much insight on the various matters that have been addressed in your feedback.
@CEE, you are doing a wonderful job. Do not stress if you miss little things here and there. w.r.t the “wood&Amor” moments I am able to recognise this because of YOU, I am proverbially standing on your shoulders. Without your clear explanations, many things would still be hanging in doubt for me. Be proud, because your wisdom is being well received.
Regards, DK
I have finally catched up on your videos, and look forward to following your videos as they are posted!
I dont expect you to answer the questions below, but if you have the time, I would appreciate your thoughts on the following:
I am really interested in the technical insight you present, and look forward to more info about the meshing. I guess subjects as shear locking, hour glass modes etc. are not super relevant, as Robot only presents elements which are not vulnerable for such? Anyway, it would be great to hear more about the elements they do present, I remember you talked about a discrete Kirchoff-Mindlin element (or something:D). I know that ideally, the elements should have as little distortion as possible, and optimal meshes should have as straight and even angles and side-length ratios as possible. What are your thoughts on this, taken the elemenet-types Robot present into consideration?
I have also wondered about another topic - concrete stiffness in Robot.
I was doing a simple experiment with a cantilever, rectangular beam, and it showed that the stiffness simply was E*bh^3/12 (EI) - like as the concrete have the same properties in tension as in compression. However, the stiffness of concrete is quite complex(cracked, non-cracked, reinforcement-ratio and so on). Do you have any thoughts on this, and how to represent this numerically in Robot? I remember you talked about stiffness ratios between carrying beams and slabs in the pedestrian bridge series. In this case, this issue is highly relevant.
A final thought about this (sorry for overloading), is how relative stiffness will affect a floor in a floor-ground interaction. Would you agree that a super stiff ground(This is probably never the case, but in a theoretical point of view) would make you treat the floor as a strut and tie-model - that is, distributing the loads at an 45deg angle or something down to the ground giving you a very limited load area on the ground, while a relatively soft ground would let you treat the floor as an upside-down slab, with the point loads as the columns, and the counter pressure from the ground as a distributed load?
I would finally just let you know that I am exited for the dynamics you will present(loved the prev. vids about this), as you are an expert on the field (and i am very much not). It would be very insightful to see how theory fits the FE dynamic results. Could you for example compare dynamic results from Robot in a simple beam or frame with some relatable hand calculations? If I do remember correctly, we assume certain deflection modes as chosen functions, like ø(x)=sine(n*pi*x/L), n being the mode number, and then use this to find the frequency. Demonstrating something like this (and other solution methods) would be perfect.
Thank you for your videos!
Hi there, Happy you liked those
As a matter of fact, I do read all comments and answer most of the questions. So here you go:
About Meshing, this is the topic of the video: The Slab Series | Part 3, so you can expect it soon (I am preparing Part 2 at the moment)
I will add those technical details about meshing such as shear locking into my account. I will try to find a simplified way and strike a balance between a "general purpose video" and "some insights for the more technically interested people".
Indeed, you are right about the "distrotions" of the elements. Now to give you some food for thought, the elements you see here are actually transferred into an "alternate reality" called the isoparametric element. The element is mapped onto that isoparametric member. Now the more distortions you have in the original member, the more the "mapper" has problems in mapping your element to its "alternate reality sibling". Now the technical terms involved are: isoparametric formulation, jacobi matrix, determinant of jacobi matrix. I do not think I would go into such detail in the mesh video, but I still have the scientific obligation to tell you about these things.
Now those shortcomings can be remedied by decreasing element sizes, but of course, this comes at increased calculation cost.
Yes
Thanks for your efforts, creating super great content.
You are most welcome 👍
Great video Sir.
Very detailed and full of useful knowledge.
This is a good video to celebrate your milestone of 1000 subscribers.
Continue the good work.
Hello there Engr. Nii,
thnx a lot ^_^ it is just a part of a multi-parter about slabs, stay tuned for more content.
Also, thnx a lot for being around all that time, I wish you all the best.
Regards,
CEE
32:45 Robot missed an opportunity here to add hook settings for up / lower reinforcement separately
33:59 You argued you are >personally < against big spacing. But isn't it generally correct to maintain a short spacing, in order to have a good reinforcement aka more homogeneous? Cracked slabs come to mind 😬
I agree totally, it is generally good to maintain smaller spacing. But it is not all black and white,
You see, the codes give "min" and "max" values, and it is kind of a spectrum in between.
Go towards the min, and you are going to suffer in concrete placing (coz some people forget that there is other steel to be considered in a slab such as the column steel)
Go too far, and you are risking cracking.
Anyways,
Nice video, thank you effort if you could please do another video about basement wall, because when I try to calculate the column in the basement there is no continuity of the load from the above stories .
That is a great suggestion. I know why this actually is, and will tackle it. It is an amazing video suggestion! thank you very much
Excellent, as usual.
Most welcome, happy you liked it.
You're simply the best
Thnx a lot ^_^ stay tuned for more content.
@sangmolandry977 Better than all the rest? 👀 😂
amazing content! Thank you so much
I am happy you liked it. Stay tuned for more content.
Regards,
CEE
Hello, first of all thank you for the very clear video, I have a question what are Ar, At, and As in the software what does Ar/At < 1 mean ?
hi there, happy you like the videos.
Could you please mention the time-stamp of your question? I am more than happy to clarify.
Regards,
CEE
@@CivilEngineeringEssentials Thank you for answering, problem solved ^^'. Do you have any video related to design of dynamic loads such as movement of car/lorries on a road ? Do you know if there is a way to check the fatigue in robot for dynamic loads ?
Good day CEE,
I trust that you are well.
This comment is with regards to the meshing of the current slab. I have just observed that if one uses a “coarse” mesh, the results of reinforcements distribution (even the results of the slab bending moments Maps) are not wholly symmetrical as one would have expected them to be? However, if one changes the mesh to either “normal” or “fine”, then the results become symmetrical (as expected) and within the bounds of the slab geometrical dimensions and configuration of course.
Now I appreciate that a “coarse” mesh will not give same “smooth” results as say a “fine” mesh. I had thought (I mean, I assumed without an actual referable basis, shame on me ☹😞) that the “coarse” mesh, as “rough” as it may be, it will be “equally and symmetrically” rough on both opposite sides that are expected to behave symmetrically. Clearly this is not the case.
What concerns me about this is as follows:
• Does this now mean that a “rough” mesh can create “non-existing” imbalances on two opposite sided that are otherwise geometrically symmetric and even loaded symmetrically?
• If so, how then should designers trust the analysis results of a multi-storey structure with appreciable amounts of slab elements when the structure as a whole is analysed using “coarse” mesh settings? Would the “imbalances” if they exist not “distort” the true-er behaviour of the structure?
• Is it advisable to run analysis with only “normal” or “fine” mesh settings?
Perhaps some of what I mentioned is something CEE is still to cover in the planned meshing video? If so, I can get clarity when that video is released.
Keep well, DK
Hi there, Engr. DK
If you are using coarse mesh, the FEM mesh is not double axis symmetric (x symmetry and y symmetry), thus there is a slight stiffness difference which causes the unsymmetric moment diagram and thus the reinforcement.
Yes, a coarse mesh creates imbalances, I will address this in my next video which is all about meshing. Actually, the reactions of the identical columns would not be identical. Edge columns will have different reactions.
Secondly, indeed, due to this slight problem in the mesh, your multi-story structure will create "twisting motions" even if it is 100% double symmetric. This is something that all my graduate students face and ask me about. I will definitely talk about this in my full structure series. There is some really juicy content to talk about. (Gonna tell editor to add this point to the list.
For me, it is actually advisable to run coarse mesh settings for "quick structural checks" and fine settings when you are getting "serious" and want to export designs. Of course, this will be covered in my mesh video next time.
The mesh video should be released next Friday (hopefully).
Regards,
CEE
@@CivilEngineeringEssentials
Thank you so much for this feedback.
It is now even clearer to me that without understanding the FE method, one could do some serious damage with it. The CEE community is fortunate to have you who clearly understands well how the FE method works
You are amongst the rarest of the best.
Keep well.
DK
Hi,
I am structural Engineer in Germany. Curently working with Dlubal RFEM, Infograph InfoCAD, MB Aec, Nemetschek Frilo.
I am concidering to by Robot Structural Software to do some Projekts in UAE and in Poland. Then I would use Robot also for some Projekts in Germany.
My Question to you is it possible to calculate a flat slab and automaticaly take the seactons as Load for the slab below?
I know you can do i ti in 3D but for some specific Projekts in Germany 3D Static is not allowed. With Rfem and InfoCAD, also with MB and Frilo i can take Reactions as loads but I am not sure if Robot can do it?
I would be thankfull for your answer.
Halli Hallo, toll mal auf deutsch sprechen zu koennen. Ich habe Sie leider nicht 100% verstanden. Sie meinen, dass Sie in 3D modelieren wollen und die Auflagerkraefte (mein Keyboard hat keine Umlaute) zu exportieren?
Das geht einfach: Menu: Results -> Reactions
Im Fall das Sie etwas anderes meinten, koennen Sie gerne hier 'ne Antwort schreiben.
Immer Gerne,
CEE
@@CivilEngineeringEssentials Hi, ich wusste nicht dass Sie Deutsch sprechen.
In Deutschland macht Mann fast immer so genannte Positionsstatik. Das bedeutet alle statische Positionen werden separat statisch betrachtet und gerechnet. In dem Fall rechne ich eine Decke zum Bsp. Decke über 1.OG als 2D Decke/Platte und übernehme ich die Auflagerkräfte dieser Decke als weitere Belastung für die untere Decke (In dem Fall Decke über EG oder für die Bodenplatte). Ich weiß nicht ob Mann Auflagerkräfte eines Modells als Belastung für ein anderen Modell in Robot übernehmen kann? 3D Statik ist in Deutschland nicht immer zugelassen und auch nicht immer prüffähig. Robot kostet schon was und wenn ich den Programm kaufe dann würde ich Robot auch für weitere Projekte in Deutschland nutzen. Aus dem Grund ist diese Frage für mich sehr wichtig.
Vielen Dank!
Mit freundlichen Grüßen
Dipl.-Ing. Kemal Halitovic Bauingenieur
mail@ing-halitovic.de
Statik / Konstruktion / Brandschutz / Schallschutz / Wärmeschutz
@@CivilEngineeringEssentials Hallo, ich wusste nicht dass Sie Deutsch sprechen.
Meine Frage ist ob in Robot möglich ist Auflagerkräfte eines Modelles als Belastung für ein anderen Modell zu übernehmen?
In Deutschland ist leider nicht immer erlaubt eine 3D Statik zu erstellen. Sondern wir machen hier fast immer so gennannte Positionsstatik. Bei dieser Statik werden alle Positionen einzeln statisch betrachtet und gerechnet. In dem Fall rechne ich die Decke über z.Bsp. über 1.OG als 2D Decke, dann übernehme ich Auflagerkräfte dieser Decke als Belastung für die Decke über EG. Das ermöglicht sehr genaue statische Analyse und einzelne Nachweise sowie eine sehr saubere Dokumentation und klare Lastweiterleitung.
In Rfem und MB, InfoCAD und Frilo z. Bsp. ist sehr einfach die Auflagerkräfte eines Modells al Belastung für ein anderen Modell zu übernehmen.
Kann mann sowas auch mit dem Robot machen und wenn ja wie kann ich dass machen?
Falls dass ich den Robot kaufe würde ich den Programm gerne auch für die Projekte in Deutschland nutzen aus dem Grund ist diese Frage für mich sehr wichtig.
Vielen Dank im Voraus.
Dipl. -Ing. Kemal Halitovic
mail@ing-halitovic.de
@@Guru_091Gru Oh, jetzt versteh ich wass Sie meinen. Genau, in DE kann mann nur einzelnachweise fuehren (z.B. Harzer Statik)
So einfach ist es nicht, die auflagerkraefte auf nen anderen Model zu uebernehmen. Mann koennte zwar die Auflagerkraefte von (Results -> Reactions) anschauen, aber die einfach weiterzuleiten geht leider nicht. Es waere zwar moeglich, es nach Excel zu exportieren und irgendwie diese zu importieren, aber das ist nicht die haufen tausend Euro fuer Robot wert.
Sorry dass es laenger gedauert hat, zu antworten.
Viel Erfolg und MfG,
CEE
@@CivilEngineeringEssentials Schade.
In Rfem zum Bsp. das ist nur ein Klick, in Frilo und MB auch, im InfoCAD Mann muss 3 mal klicken :D
Hi there CEE.
I am really enjoying your videos.
I´d like to know if its possbile to run a plastic (i´m not sure that´s the correct word in english) analysis for slabs (shells). In other words, i´m not confortable with some results i´m getting of a particular RC structure that i´m looking at, it seems too stiff. In my country, for shells, our code allows to simulate plastic pinns located on the critical sections through a non-linear analysis, and establishes a limit for rotation of tha pinn in miliradians due to a moment/shear ratio, section geometry and ductility parameters. That allows to redistribute moments along the structure. Is there a way to simulate this kind of behavior on Robot?
Hi there Engr. Vitor,
I am happy you find the content of this channel beneficial. It help if you want to suggest it to your friends.
About non-linear hinges for plates, I have to check if there is something like this in robot. I would make a video about it if I find it ^_^
Anyways, stay tuned for more content.
Regards,
CEE
Can you go through ribbed slab
Yes, definitely on my list on the Slab Series. 100%
Waiting for a video designing for solids or volumetric elements
I have it on my radar ^_^ I need to finish the RC design series first.
Always have problems with slabs result in RSA😅, don't understand the result for required Reinforcement X-,X+,Y- and Y+.
Even Mx,My, Mxy
Not talking about provided Reinforcement, the results of numbers and colours(orange&blue on the slab) totally lost!😅
Results for slabs are always a problem to read and need some head wrapping around 😄
Nice
Thanks. Stay tuned for more content.
18:03 (reaction to editor) I had a haunch...
No... actually, I KNEW IT! - I will not video-edit this comment 😅
Actually, there are four of us running around (Recorder N00b, Witty Editor, Subordinate Teaching Assistant and the Dr. himself).
There is another guy in the shadows, he was mentioned only once in 1 video.
Oh also, usually it is the editor personality who is responding the comments. While loving to roast his recorder n00by, he is actually quite nice to his viewers and subscribers.
LOL, not gonna video edit it neither.
Stay tuned for more content.
CEE
Quite the setup 😆 I missed the "other guy", but for the 4, I can actually identify them.
FYI I find myself pausing the video for reading your comments over the recorder voice and the YT controls overlap - I wouldn't recommend reducing the recording size for the sake of clear comments, cause it's still readable, but I thought it's something you should know.
@@razvanmure that is a great piece of advice.
So, it seems to be the "positioning" that might be a tad off. I see.
I think I do have some space on the top, so I might push the recording further upward and try keep my comments up a little bit.
Makes sense to me. Thnx a lot ^_^