I passed CA seismic exam on my first go. Walked away feeling like I didn't have a good grasp on the topic. You did in 15 minutes what I couldn't learn in 100 hours of studying. Thank you.
If one can understand what you teach in one sitting, then you know you have done a good job. I subscribed immediately after watching the video. Thanks. Civil Engineer from Lagos, Nigeria.
I really appreciate your effort on this. In my university the lessons skips the basics and the explanation on those basics, but you are so clear to spell out this. Thank you! I really want to become a good structural engineer, regards from Chile.
I have to write a paper where this appears and all the textbooks where just filled with absurdly complicated graphs and equations. Thank you so much for making this! It really helped me out a ton
I've just watched 2 minutesand already I know the very basics - and can see I'll be shown further basics in quick time. Very informative and well explained [I'm a UK-based structural engineer with virtually no seismic design experience. But now I've been put on a Saudi project in the most seismic end of the country and need to get my understanding up very quickly!]
I am glad the information was helpful to you. My long term goal is to include a complete seismic design guide for structural engineers. However, currently I have just touched the basic concepts. God willing I will work progressively to complete my goal as time permits. In Saudi Arabia, there are parts that are highly seismic especially in the south and you may reach Seismic Design category D or E, and this may need special consideration in the design and detailing. Good luck with your work.
Undoubtedly great video, thank you. Constructive criticism from a non-engineer (and general advice to presenters of all kinds): Give the point of the slide at the beginning instead of the end
Request to explain for multi storey building also - many unanswered doubt get clear sir thanks alot for your efforts & we the junior structural Er request you to touch all topic related to earth quake analysis
1. We scale up the base shear obtained by Response Spectrum Analysis (RSA) to that of the Equivalent Lateral Force (ELF) method. But when RSA base shear is higher than ELF method, why don't we scale down RSA to the ELF ?? 2. Response acceleration should be zero at T = 0 in response spectrum curve. But response acceleration is starting at coordinate equal to 40% of SDS (by formula). Why is it so ??
thanks for such a nice video..but i steel did not understand how we convert time-acceleration (earthquake data) to accelration-period (design spectrum)? Becouse earth data comes with time and time converted to period...in this particular transition what formula we use? have any video to explain pls or planig to make such a video? thanks
This process of changing the seismic acceleration data to response spectrum is explained briefly in the video as it is not the main intent of the video. It was just mentioned as a mean of explaining what is a response spectrum. I hope I will be able to do a separate video about this step when time permits. However, most designers don't need to do this step, since the response spectrum is given in most design codes like the ASCE7 code and the Eurocode and all other national codes.
If you look at the equation of motion of a SDOF building subjected to earthquake motion ( In dynamic analysis books) you will find that the relative displacement (U) of the building is directly related to the acceleration of the earthquake motion. Recall that the relative displacement (U) is the difference between the displacement occurring at the top of the building and the displacement at the foundations . From the response spectrum curve you obtain the acceleration of the earthquake, from which you can obtain the earthquake force, and from the force you can obtain the relative displacement (U).
@@drnafie-structuralengineer4620can you explain why the natural period is different in x and y direction. Initially when we calculated T based on storey height as a single number say 2s or 4s.
Thanks for the kind video. I have one question about 6:40 . How to determine the range of X-axis to watch out for? Do we need to implement modal analysis for a given system? For example, if the natural time period (T) of a given system is 2 (lowest) to 4 (highest) through modal analysis, can we conclude that the effects of earthquakes are similar to the given system?
I am happy the video was helpful This video is concerned only with the single Degree of Freedom systems (Only one Story). There is another video for Multi-Story Buildings. For one Story Buildings. IF 2 buildings with the same T is subjected to the same Earthquake, they will both have the same response acceleration irrespective of the shape or size of the building. But the Forces acting on the buildings will be different. The force is equal to the acceleration multiplied by the mass. So the mass will also affect the response.
Thank you very much. The best explanation of Response Spectrum I have found. Its something I've been trying to really understand for a while. Minor typo error at 10:52 where Sa in Y-direction is first stated as 0.056g but then calculation based on 0.192g.
I am glad you liked the video. Yes you are correct. The correct value is 0.192 g, thank you for your feedback. However, it is not possible to correct a you tube video once it is posted. God willing, I will correct this type in the next version of the video.
Assalamualaikum Sir. As a 2nd yr student in BTech Civil this was super helpful. I came across this word response spectrum and wanted to know a bit more about.
Very informative video and explained the concept very easily. Thanks for the video. Can't wait for multi story building RSM video. Also can you please start a course on Earthquake Engineering?
I am glad the video was helpful. I am currently working on the Multi-Story Response Spectrum lecture. God willing, I hope I can Upload it soon In Fact Response Spectrum is part of an earthquake engineering course. However, I am not taking the course from down-up, Eventually, after covering enough material in the lectures, I hope to re-order the lectures into a complete Earthquake design course.
Sir, At first, you drawn the curve, by keeping the mass constant and changing the height for getting different Time period (T) and working out on a particular EQuake Data, for obtaining a response spectrum Curve. Right? Sir, in this process, if we workout for a building with a different mass, then the curve also changes, As the mass is a dependend factor, right? then how is it possible to multiply a random building mass with the acceleration, corresponding to a partiular time period, for obtaining its shear force???? please help
To explain this point we have to differentiate between two things. The building acceleration and the shear force. When the building is subjected to a certain acceleration at its base ( the earthquake acceleration), the building will start to respond by its own acceleration ( the response acceleration). This response acceleration is dependent on the building natural frequency and not on its mass or stiffness. Of course the natural frequency is dependent on the ratio between the mass and the stiffness. If you change both the mass and stiffness so that the ratio is constant the response acceleration will not change. It will only change when you change the ratio between the mass and the stiffness. That is why in the video we changed the stiffness (by changing the height) without changing the mass (i.e. we changed the ratio so we changed the natural frequency) and therefore the response acceleration also was changed. Of course in structural analysis we are interested in the force and not the acceleration. The shear force is equal to the acceleration multiplied by the mass. So to answer your question, the seismic force is of course dependent on the mass, but the acceleration is not. The acceleration is dependent on the natural frequency. The response spectrum curve give us the response acceleration and not the force. When we obtain the acceleration from the spectrum curve, we multiply it by the mass of our building to obtain the force.
@@drnafie-structuralengineer4620 I noticed for as you increased the height of the building to produce different time periods, the graph went down despite the increase in height... please explain
