Etabs 2015 - Response Spectrum Analysis
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- Опубликовано: 1 авг 2024
- Etabs 2015 advanced tutorial deals with the response spectrum analysis which is a method of seismic analysis considered for irregular or tall buildings.The tutorial is based on codal provisions listed according to ASCE 7- 05.Steps illustrated in the tutorial can be followed for other international earthquake codes.Following are explained in the tutorial:
(1) Defining load pattern 2:22
(2) Defining Mass Source 3:25
(3) Modal cases 3:49
(4) Response spectrum function 4:47
(5) Defining scale factor 7:07
(6) Modal participation mass ratio 10:16
(7) Scaling of response spectrum base shear 13:18
Tutorial starts with an introductory explanation about response spectrum analysis.The load patterns and mass source are defined according to ASCE 7-05. For detailed explanation on this part , beginners tutorial can be referred.In the following steps modal cases and response spectrum function are defined and while defining the load cases,the method of scaling the response spectrum function is explained.After the analysis, modal participation mass ratio check is conducted to make sure that the number of modes considered for the analysis is sufficient or not.In the response spectrum base shear check,the obtained response spectrum base shear is scaled up to 85 % of the static base shear for the dynamic analysis.
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Dear Sir, You may not know how this video solved my big problem and made my life easy....I have never ever seen such complete and clear video even from the developers of Etabs and SAP2000 software. ..Sir, Please make such comprehensive videos on ''Time History Analysis'' and ''Pushover Analysis''...Waiting to hear from you soon....Thank you so much for the great work.....
+Nasratullah Amarkhail yeah ...sure..
Why you don't use IS code? Pls use is codes
Thats fantastic and career shaping video. Need more like this.
Best explanation i have ever found.
Thank you so much for the great work! This video is very usefull.
BEST OF THE BEST EXPLANATION. THANKYOU 🖐🖐🖐
I love your work my brother... beautiful
Thanks a million for your useful videos and content, please do keep it up!
+Farzad Hakimi thank you....yeah sure..:-)
Nice and clean video small and accurate illustration thank u very much keep going
+Muhanned Othman Glad to hear that...thank you..:-)
Thanks a lot Sir.
A BIG thanks to you :)
Nicely explained sir thank you
Nicely explained.....best ..sir
Great very easy and power video
Thanks a lot,Really very clearing tutorials for spectrum analysis.Sir Plz make such comprehensive videos on ''Time History Analysis'' and ''Pushover Analysis''.I am waiting for your response.
Thank you for your nice and useful videos! If we have three different structures. the plan is one but the structure is different. 1) the structure is made of columns and beams. 2) the same add a few shear walls. 3) no columns and beams only shear walls. if possible to do dynamic analysis for all of them and compare the result. would be nice of you.
First of all it was a fascinating tutorial. I would like to know when I am going to design for sections do I need to create additional load combinations incorporating Response Spectrum load case? Also this is new for me but based on your experience does response spectrum analysis give better results than static one in high rise buildings or does it make worse (based on it's purpose)?
thank you for wonderful explanation, I have two queries, first is whether I have to run model in set cases only for Response spectrum only?? second is that about how much Response modification factor R value under ubc7 for apartment
Thanks for the tutorial. A question please. If I must find the forces in each story for do the diagram of the sum modals diagram. Where I should check? Thanks.
thanku so much
thanks !
should scale factor in x and y direction be same? can i scale them by different amount so that both of them produce 85 percent of static base shear.
how can i find
0.2 Sec spectral Accel. Ss ??
1 Sec spectral Accel. S1 ??
and long period Transition period ??
For the Response spectrum and the static Ex.
Thanks bro 🙏
Dear sir
Does the scale factor have to be the same for x and y direction after re-scaling?
How to you calculate long-period transition period?
How can analysis the RS by using 1893:2016 and push over analysis
Hello ! Can you please tell me that the results obtained from ETABS analysis( Base shear, Displacements, Drifts) are already amplified or they have to be multiplied with the force modification factors (R in ASCE or Rd-Ro in NBCC)?
can you please provide pushover analysis of RC building in etabs by capacity spectrum method with IS
What is the difference between given time period in load pattern and getting time period after analysis ???
Sir, it is a nice lecture.It help us very much as well as students. It will be more helpful to me if you kindly mention the name of good books for dynamic analysis.
Thanks.
Thi
load assign and load combination are of same as that of static analysis ?
Kindly note that,those want to apply response spectrum analysis according to Indian code,please use scale factor as I.g/2R instead of I.g/R.
what value should I use for "I" and "R" according to Indian Standard?
only "I" I know in Indian Standard is "Importance Factor". Is Occupancy Factor same as Importance Factor?
Should I use value of I=1 for residential building?
If not what will be the value of I for Indian Standard?
And Only "R" I know in Indian Standard is "Response Reduction Factor" which is R=5 for special moment frame.
Is "Response Reduction Factor" same as "Response Modification Factor"?
If not what value should I use for "R" for Indian Standard?
I used same value of scale factor as yours in my model ie 1225.83.
And got Fx of RSmax= 124% of "Fx of EQx"
and Fy of RSmax=114% of "Fy 0f EQy"
"
would I be designing the structure stronger than necessary if "Fx of RSmax" or "Fy of RSmax" exceeds 85% of "Fx of EQx" or "Fy 0f EQy" respectively?
Also my sumUX, sumUY, sumRX, sumRY and sumRZ value exceed 0.9 in mode 7. So, should I reduce the number of modes to 7 or assigning any number of modes greater than 7 is ok?
All of my sumUZ value is zero but RZ value is not.
Is it ok if all my sumUz values are 0?
should all sumRZ values also exceed 90%?
I=1 and R=5 will do for residential building. The default no. of modes is 12, and if 90% of the building mass gets excited within 12 modes, then you don't have to change anything. Uz is basically displacement in z-direction, and earthquake force being applied in lateral directions only, we are bound to get Uz zero. Yes, sumRZ should be > 90%.
Dear Sir could you send me the above etabs model to my mail
can u please provide reason why we use (i. g/2R)? instead of (i. g/R)
@@MdAhmed-vg3dn Design base shear by dynamic methods shall not be less than same calculated by equivalent static method hence result forces must be augmented by a factor according to code IS 1893-16 7.7.3. As far my knowledge there is no such similar clause in international codes.
above increments operation is only required for forces, not deflections and drifts according to code, it is a question of rationality rather than the benefit.
Initial Scale factor IG/2R is nothing do with the code, it is part of the formulation.
if spectra acceleration is normalised by g (unitless) we should use IG/2R. if you happen to work with field spectra with acceleration where it is not normalised ( units are in m2/s) then use I/2R.
Why Cd (Deflection Amplification) factor is not used at 8:53 time?? Help me please
Thank you very much for this!!! My question: So after re scaling, we get a 2753.25 value, wich is introduced as the new scale factor, on the load case RS. Therefore, now our new R (response modification factor) gets to be 9806.65/2753.25=3.56. (and before it was R=8!). Is there any section of the code which allows this change? or is this justified by saying that we achieved the 85% of the base shear?. Finally, just reminding the audience, that the displacements values now will have to be multiplied by 3.56. Thank you, Sir!
please tell me why you didnot make acombination between the horizental forces?
Sir, Kindly tell me if the RS analysis has to be done before defining load combination + envelop And does load combination effects the RS analysis ?? Please Reply ASAP!
Sr. I am using G+10 model which one is more appropriate to analysis static or dynamic analysis ?
How to select the type of seismic design method i.e static or dynamic for an RCC building ?
could you please provide the geometry layout of this building ?
Please how do we design columns and shear walls next to the analysis? And it was a very useful tutorial... God bless you
Hi, Can you please tell in case we have a Importance factor more than 1, what happns or what shall be changed in static definition of the Earthquake, because, otherwise we get a difference in base shear values after application of scailing.
WOW NICE PRECENTAION
what do "Sum UX" and "Sum RX" in "modal mass participation ratio" table mean?
Sir can you please upload a vedio how to to modelling of a mass tuned damper in a building
can u pls explain modal mass participation table in all details..till last col. of Sum of Rz, with there min. & max. values required for being safe Structure. Pls explain tortional modes & min. max. values of it, how to remove it.
pls upload video for same.
sir, why you tries for vertical response spectrum
Should we design the building for response spectrum analysis results?
I think it will be more helpful if you are explained the behaviour of graph obtained after analysing... Which includes what is crt and can be adopted
Sir please make a video for same response spectrum analysis based on Indian code.
Please make a video tutorial on seismic design of soft story building by modelling the wall as struts and performing dynamic analysis.
+beenay18 will try if tym allows
How to put response spectrum in Load combination?
Sir I have analysed a model for response spectrum I have created load cases for response spectrum but while analyzing it is being displayed that loads could not start please give a solution to this problem
may i know the difference between civilknowhow and fieldready
Sir,
Can a response spectrum data created in MATLAB or excel sheet be inserted into etabs?
May i kno what is the load combination for RS Max.
Thank You
1.2
Sir how to get the response spectrum curve on etabs
what are these factors ?
R,Omega,Cd and I .
and
where can i find out them and how can i find there value?
are the predefined in the code or they depend on the area in which the building is located?
Hello, I'd try to answer this. Usually, we can find these factors on you country's earthquake codes. These factors are based on typical of structure we design to use
If i am not permitted to use static analysis should i use ig/r scale factor or not please
How to show Tx and Ty in table??
Thank you sir, it is really useful tutorial. it cleared lots of doubts i had regardingly but dont know how to find the number of joints for a concerned project?, as you mentioned: "This project comprises 2833 joints".
+Sa Qadiry it's from the analysis file..
Sir how to done response spectrum analysis as per Indian standard
Plese explain the modal participating mass ratio table
How to see shear force distribution in specific storey
how was the calculation done for Ss and S1 values
Sir, could you please teach us about p-delta analysis ??? in etabs
Sir why scale factor required in rsa??
ASCE 7-05, in order to consider the live load for effective seismic weight calculation says ''In areas used for STORAGE, a minimum of 25 percent of the floor live load is considered''. Do we have to consider this 25% of live load in mass source for office or residential buildings as well or only for areas used for STORAGE?
+Nasratullah Amarkhail it depends on the type of buildings n the live loads applied...it is better to take 25 %
good tutorial. how to get Spectral acceleration values Ss & S1?
From USGS in US or from site geotechnical report
how do we assessthe .2 sec and 1 sec. response specterum.
many thanks sir ... why the vertical component of earthquake in buildings is not considered
+Saria Osman bcoz the vertical excitation is negligible n the major effect is due to horizontal ground acceleration..
Nice
sir how to find out base shear
Is the formula for computing the scale factor ''Ig/R'' taken from ASCE 7-05?
+Nasratullah Amarkhail it is based on asce asce seismic response coefficient formula...check the csi forum
is the I.g/R written in code?
Dear Sir
Please upload some videos for shear wall and its optimization. I am concerned about its size and location in the structure.
+Hamid Nikzad provide 20 mm thick wall...around the lift area..that's it's usual location
Civilknowhow Tutorials Thank you so much for your reply
Currently I am doing research on RC frame-shear wall system optimization so I was wondering if you could upload some videos related to shear wall optimization by etabs.
I am confused with how to decide the length of the shear wall based on ACI code.
thank you so much
@@Omid_RayanAsalamualaikum Mr. Hamid,
currently i am pursuing btech
could you send me dynamic analysis highrise shearwall building etabs model to my mail so that i could do learn for my project
ples. upload single footing design by safe
sir why did U didn't given the wind load
in defining RS case y u take U1 & U2 instead of U1 & U3 ?!
please do give response spetrum analysis as per is code ,sir
What as per is code and please tell the clause and code
Dear sir, can you please tell me how can we check our foundation size with the help of this data mean to how can i calculate my footing size by using my etabs model please help me regarding this. and this was really a very helpful video
late but thank you for this tutorial.sir, according to Is code we will be using the scale factor of I.g/2R as mentioned in your comment, my question is what will be the re scaling factor according to IS code will it be Ig/2R 0.85 *static base shear/RS spectrum base shear ? your reply will be very much helpful.
If I am using Indian Standard,
is "I" importance factor? ie I=1 for residential building?
Is R response reduction factor? ie R=5 for special moment frame?
Is it supposed to work like this for Indian standard:
So you put the scale factor as I.g/(2r) at first.
And then you run analysis.
And then check " (Fx of RSmax)/(Fx of EQx)" and " (Fy of RSmax)/(Fy of EQy)"
if one or both of the ratios is less than 0.85
re-enter scale factor as (Ig/2R *0.85 *static base shear/RS base shear)
And then run analysis.
Then "static base shear/RS base shear" value will be equal to 0.85 for one among fx and fy
and that value will be equal to or greater than 0.85 for another among fx and fy.
at first i got I.g/(2R)=9806.65/(2*5)=980.665
I entered the value in scale factor and ran analysis.
Then I rescaled the scale factor according to above procedure.
but I didn't got "static base shear/RS base shear" value equal to 0.85 for one and more than 0.85 for another.
both "static base shear/RS spectrum base shear" value were lower than 0.85 for both fx and fy in my case.
Does it mean that above procedure does't work for Indian Standard.
+hero me according to Indian code scale it to total base shesr
+beenay18 yes
Can u upload the cad file please ??
how to take X value
hello, do you have a video regarding non-linear static analysis?
+Mark Anthony Gumamela don't hav one nw...but wil upload soon
thank you and I am hoping that you can upload a sample
Is non linear static analysis in etabs also called push over analysis?
Is non linear analysis is a form of dynamic analysis like Response spectrum and time history analysis?
Helo sir
My Ex is coming 2366.095 and RS =2387.331 at scale factor 40only .units is FPS system .is this value ok or i made any mistake? pls help
Sir, in the video, for re-scaling, why the same value is used for X and Y directions? while the RS base shear is different for both directions, hence we get different scale factors.
+Nasratullah Amarkhail different scale factors are used ....pls do check the video
I checked it, 2753.25 (which is calculated considering the X-direction RS base shear) has been used for both X and Y directions...
+Nasratullah Amarkhail scaling up the min base shear value to 85 %...base shear in other gets increased propotionately
@@civilknowhowtutorials7100 can't we put different scale factors in U1 and U2 so that we get 85 percent of static base shear in both x and y direction.
Sir please upload some videos on progressive collapse analysis ...pls make a video on interpretation of results of response spectrum analysis
Hai sagar
R u doing project on progressive collapse analysis
Can I have your contact number plz
I can help you
sir I have done time history analysis I have defined the functions and load cases of time history analysis but after the analysis I am getting the time history analysis results as zeros what to do to get the results plz guide me plz help
+mohammed khaja salahuddin All the results zero lyk moment shear n displacement??
+Civilknowhow Tutorials
yes sir displacement,moments,n shears are zeros what's the problem sir can u plz solve my issue
how to determine the number of modes for a high rise structure and
how to determine number of degrees of freedom for each mode
+mohammed khaja salahuddin set your model to high number of modes..for eg more than 200...n analyse...analysis wil take quite a tym n while analysis click on show analysis option in the footer....then u wil b able to see no of modes n joints at the beginning of calculation...degrees if freedom will always 2 for spring supports
OK thank u if I get any queries I will ask u for that can u plz give your email id
8:42 and 14:45 have been reserved
Dear Sir, In my case, I got base shear from RSA more than the linear static base shear....Is it okay or there is something wrong? because normally we expect base shear from RSA to be less than the linear static base shear...Thank you.
+Nasratullah Amarkhail what's the percentage in in RSA base shear wet to static base shear??
+Nasratullah Amarkhail what's the percentage in in RSA base shear wet to static base shear??
I got the point....at first, I didn't divide the scale factor by R. ie. g=386.4 in/s2 was not divided by R=8, where I=1. Now its okay. I got the right RS base shear and scaled it up to get minimum 75% of the Static Base Shear.
what is the significance of Scale Factor?? What does it indicate?? We are modifying Scale factor, if it is not in limit, what are we exactly doing to structure??What is the limiting ratio of Earthquake Base shear to Response Spectrum Base shear according Indian IS 1893 code???
+Keyur Tailor The significance of scale factor is to ensure accurate distribution of earthquake forces throughout the building frame members...
+Keyur Tailor Refer IS 1893 7.8.2 for scaling..
+Keyur Tailor Use scaling factor as Ig/2R for scaling with Indian code
thank you for your reply.
Can you please tell me the unit of gravitational acceleration you have defined in your video tutorial???
+Keyur Tailor mm/s2
Sir, in case of tall irregular buildings, the moments and shears for design, should they be based on RSA analysis or static linear (ELF) analysis?
+Nasratullah Amarkhail RSA analysis is btr
Sir, Where can i find the scale factor = Ig/R in ASCE code? could you please tell me which chapter of ASCE mention this scale factor? Thanks Sir
+Mi Mi Khine Soe it's based on seismic coeff calc in asce ...but no direct formula is provided..check the csi forum for the formula
Dear Sir,
Sincere request to send me e mail id for solving my confusion about RS ANALYSIS IN ETABS
VK
should scale factor in x and y direction be same? can i scale them by different amount so that both of them produce 85 percent of static base shear.