Thanks Dirk Bondy for this material. Sometimes, the technical folk in our industry are a bit arrogant and look down on you when you ask questions. I appreciate your down to earth attitude and your clear and concise explanations.
Dear Mr. Dirk Body, I hope you are well. I am writing this post to express my sincere gratitude to you for your efforts and time to share your valuable knowledge and experience through all videos you made for us. These videos are really useful and are treasures worth saving and preserving for next generations. Once again I offer my heart-felt gratitude for your time and effort. Wish you a happy and peaceful life. With the best regards. M K Ahsan. Qatar.
Thanks Dirk, I’m a practicing chartered structural engineer with nearly 10 years experience. I really appreciate you sharing this level of content for free and I will be sure to point young engineers here when I’m fumbling around trying to explain these concepts! Thanks again and all the best.
Dirk, you are a legend. Thank you by all means for sharing your knowledge in such a great humble way. And really sad to see that your lovely wife passed away, may she rest in peace.
thank you professor dirk you helped me a lot... hope we will see other videos like this and learning from your smart way to deal with problems...I respect all the people you show us they are heroes and a reason that a hero like you are here helping a lot of engineers to make this world better
Excellent video ... Thank you so much for the concepts... Best explanation Dirk. May ur wife's soul rest in peace. Take care and keep impressing the young talents with your knowledge sharing sessions..
Almost a year ago I started my thesis about the vulnerabilty of a given structure using the pushover analysis to obtain its capacity details. It was a brand new subject for me, since I only saw linear analysis in college, and I've read a lot about this and often came to this vid for more info. I finished it today and I wanted to thank you, Engineer Bondy, for making this vid. I'm sure it has helped a lot of students/bachellors/young engineers to fully understand the pushover analysis. I sure am really thankful for all the info you've given us.
I think these along with prestressed lectures are the best I ever have seen in this field. I come to a conclusion that for being a good engineer we have to work and learn how to implement the knowledge. I hope to be the first person getting experience and taking prestressed technology to Afghanistan. Respect
Most Powerful Lecture Series. BTW I have Masters Degree in Eng. but still learning. Mr. Bondy makes it clear How ASCE 7 Equations supposed to Work, plus He gives a background on History. The day he publishes his book I am buying it. I would not worry about typos or How it will change going forward. He is just good as Tim Mays whom I love on Bridge Side.
I’ve learned a lot. I hope more structural engineers will look into that column plastic moment demand in relation to the deformation of the building. Do you have a link to where we can download the notes? Many thanks.
Hi, The lecture was insightful. I could not get your point regarding strong column and weak beam and codal provisions. Based on example you considered in lecture I have following questions: 1) Is it prudent to keep plastic moment capacity of column more than beam ? If we follow this then yielding of columns will not occur and the assumption in code of considering column to remain elastic limit over entire pushover analysis will hold good. 2) With pushover analysis we can decide up to what height we should have strong column weak beam arrangement. The height above which yielding of beams is not expected, we can do away from strong column and weak beam requirement. 3) In the example considered in the lecture, if plastic hinge forms in lower most storey column along with plastic hinge in beams then at this instance structure will collapse due to mechanism. Is it right? Regards, Sachin
Hi Dirk, Thank you for this amazing video. I am a young engineer and I too was thinking about the same thing that if we follow the code procedure of making strong column and weak beam, the column with still yield if we follow the mechanism. But I couldnt find supporting literature and thought may be I am missing something and may be I am wrong. Your video reaĺly proved it. Thank you very much.
A very good and informative lecture. I would be really happy if you will be my adviser for my thesis if ever possible. Hoping I can have more inputs and tips from you, sir.
Professor Bondy, As an aspiring structural engineer I want to humbly thank you for offering your series of lectures via RU-vid. I am currently taking a course in Connection Design for Seismic and these videos have been greatly helpful in understanding the loading analysis behind it. With respect to your book, will it also cover any Connection Design and Detailing? If not, besides the SDM from AISC, are there any additional books that could potentially aid in understanding the methodology behind it or at the very least some examples? Again, thank you for sharing your experience and expertise and I look forward to a reply. Kind regards.
I bumped into this video today though I was searching for capacity spectrum method. Such an insightful explanation of pushover analysis. Now I will watch the entire series. I read the entire paper out of curiosity. I really liked the way you simplified the the explanation of such complex phenomenon. Can you suggest me a few good literature on applications of capacity spectrum method. Best Regards.
thank you very much sir for your effort ....im very thanckful to you because you helped me to understand whats is going on in siesmic analysis word....i would like you to be my hero like sir tom was for you someday i wish if all my teacher were like you:).....and i will keep trying to do my best in this industry so .......thank you very very much again
Hello Dirk, thank you for your interesting video about pushover analysis. It gives me a simple view of the subject. But I am just wondering, why did you say that the codes do not properly design the columns?. One other thing: the philosophy of STRONG COLUMN- WEAK BEAM is not accomplished in the column of the first floor: the colum has a capacity of 1800 ft- k; the beam has a capacity of 2800 ft-k. This is against that philosophy. Why?
Hi Pedro, in most codes the equation states that it is the sum of the column strengths framing into a joint that must be stronger than the sum of the beam strengths framing into that same joint. In my example there are two columns and one beam. ACI has a 6/5 factor, and AISC has reductions on the column strengths and increases on the beam strengths, but in both codes it is the sum of the columns > the sum of the beams.
awesome video i've been searching for something like that... but i didn't understand the frame at 50:30 when the hinges appear on the roof too how do the whole system is still stable ?
Sir. I want to ask you something that is confusing me. In the pushover analysis that you perform towards the end of your lecture, you mention about strong column weak beam criteria. But in the structure I see that the columns have a less plastic moment capacity than that of the beams. Shouldn't the plastic moment capacity of the column be higher than the beams according to strong column weak beam criteria? Please clarify.
Hi Basit, The way that the codes read, the sum of the column plastic moment capacities at a joint must be larger than the sum of the plastic moment capacities of the beams. So in my example there are two columns at each joint and one beam. Notice also in my example that I use 50 ksi steel for the columns, and 36 ksi steel for the beams. Hopefully that answers your question.
@@dirkbondy thank you for your reply sir. I actually read your EERI paper and it made it very clear what you are trying to prove. I'm surprised that none of my professors told me about this issue. I have two masters degrees one from Suny Buffalo and the other from Virgina Tech but never thought of this issue. I'm sitting in my office right now and mind boggled. At least, I'm happy I'm working on bridges where we have to satisfy the weak column and strong beam criteria. We dont have this issue in bridges.
Dear Dirk, could you advise or share experience POA with X-braced frame? I am curious should we consider brace (I guess tensioned bracing only as compressed buckled member is not a part of stiffening system) and proceed loading the frame until a brace/column yields (what first happen)? Without braces it is quite predictable the sequence of forming plastic hinges, but I couldn't understand how it should be when X-bracing system is incorporated into frame. Apologies if my question seemed to be stupid 😊
Not at all a bad question. I don't have much experience with push-over analyses on x-braced frames. Their hysteretic behavior is much different than a more stable yielding beam so load distribution to other non-yielded members is more dramatic after buckling.
Hi sir, I am a structural engineering student. Would the problem of the code for the strong-column-weak-beam approach be addressed by the maximum story drift provisions? By the way, I am doing a thesis on diplacement-based design and I really thank you for this lecture.
Hi John, Well, sort of. But there is a dramatic difference between reaching the maximum story drift elastically versus inelastically. But you are correct that the objective has everything to do with the structure at that discplacement.
@dirk bondy, sir can You send me the notes you have mentioned in the video via email? I would be greatefull. One more thing I wanted to ask, for me personally its hard to follow everything in video presented as I am used to european units: force-kN, moment-kNm and so on. How do I convert units you used to the ones Ill understand easier? I am sad, I didnt get profesors like you in my faculty, this is so much interesting when presented in the way you did.
Yes, that would make sense. Many people take the plastic moment as 1.25*Mn, though to account for the actual yield strength of the beam rebar. But it depends upon what you are trying to achieve in the pushover analysis. If determining the total plastic rotation of the beams is the goal, then a lower estimate of the plastic moment would make sense.
Hi Sir, sorry I want to ask something.. When the pushover curve stops? Is there any code that regulates that? May be 10% after ultimate, or 20% or until the curves drops? Thank you
I suppose there are two answers to that. The first is that the curve goes flat after the entire frame has hinged. But you only need the curve to extend to your demand displacement. After that point the curve doesn't matter.
dear mr.dirk. Can the piles on continuous jetty / harbour or pile on slab bridge can be have reduction factor (ductility) by checking it using push over, since usually the pile is must be elastic in seismic condition
Thanks for such a good video that ı was waiting for...i have a question that how we could find lateral forces distribution and roof displacement? are thes founded from elastic or plastic analysis.? thanks so much again...
Hi Kasim, The lateral force distribution, and vertical force distribution were found in earlier videos. They are all found using an elastic analysis. I show how to find the roof displacement of the first mode in this video using the response spectrum along with the modal participation function.
Mr. i want ask. what happen if beam and coloum to be plastic ? at end video you draw the point at line coloum and beam. im still confused , what happen if stell in coloum and beam to be plastic , would the building will be destroy or get big damage . thank you
sir, when i did a pushover analysis , followed by time history analysis of a building equiped withinline friction damper i could see that my first storey was drifting more compared to other storeys. what could probably be the reason for this?
Hi Kaveri, There are many possibilities. If you modeled the base as pinned, or if your foundation is very flexible that would certainly contribute to it. Or if your first story is tall and the columns are not very stiff. Those are my best guesses :) Good luck - Dirk Bondy
This is based on our elastic drift , deflection amplification factor and occupancy factor... If you have complex structure , find the elastic drift for story under concern.. Max drift = (elastic drift * deflection amplification factor) / importance factor.
Hi Mert, You are probably going to wait a while :) Most of my lectures demonstrate how to design by hand, which theoretically could then be matched to any reputable software program. You should be able to match the results of this lecture example to SAP2000 or any other program that performs a pushover analysis. Other than referring sometimes in my post-tensioning lectures to our own software, my purpose in teaching is to teach principles, not software. Thank you for your interest.
@@dirkbondy thank you sır. If it is possible, please use also SI unit system when you talk new lectures. :) . I dont use your unit system. I am very related to your lecture. Thank you for all.🤗
@@dirkbondy First of all, THANKS VERY MUCH FOR YOUR LESSON. THAT'S VERY HELPFUL. Hello Professor, I replicated the pushover analysis in SAP2000 and got similar results for the first mode analysis, but when it comes to the second mode analysis, I get a different moment diagram for the columns. I realize that I can get the same results as your video if all loads are applied in the same direction instead of the opposite direction for the last two levels, but it doesn't seem to be correct. Is it? In this case of applying the loads as you show in the video (opposite directions at the top levels), the first element to yield would be the beam on the 4th floor, not the base of the column. I am wondering what I am doing wrong. Has anyone tried to replicate the second mode analysis? Did anyone get the same moment diagram results as in the video? I sent you an email asking for the notes. I would appreciate it if you could share that. Advice: it would be much easier if you provided a link in the video description with your notes available for download. Cheers
