Thank you for the informative video. I would like to know how the directional acceleration is higher at the lower floor and it goes on decreasing along the height of the structure?
Thanks for informative video.is it possible to combine static structural results with response spectrum?using pre-stressed setting does not seem to sum up the results (VM stress).
How to evaluate the stresses developed after response spectrum analysis ? You told in the process flow that these stresses must be included, where should it be included ?
Hello Sir, could you elaborate or share any document on calculation of the acceleration with respect to the frequency; that you have used as an input for the response spectrum in ansys at 17:11 in the video. Your help will be of great importance to my research - Thank you
Hello, I had assumed acceleration Vs frequency data for explaination of video. You can refer any relavant standard or will get from manufacturer of the respective equipment based on seismic zone.
@@graspengineering9249 Thank you replying. However, the results of my hand calculations as per IS 1893 are different as compared to the simulation on ansys, Though I have input the acceleration values as given in IS and put in a scale factor of 9806.6 (my model is in mm), I have turned on large deflections and perform using SRSS method. It will be helpful if you could also share the possible reasons for this great deviation between the results, (Does that have to do with the mass and stiffness matrix in Ansys)?
@@krittikaag Hello , First please check the natural frequency from modal analysis & with hand calculations. Also check mass participation is more than 90 % or not.
@@graspengineering9249 Thank you for being so responsive. It is strange but the model is working for a building with 2 degree of freedom, my calculations are matching ansys output. However, the frequency and displacement is not matching for 3 DOF using the same setup and same calculation procedure. Ansys is giving a frequency (mode 1) of 14,5Hz and calculation shows 10Hz. Thus, displacement as per ansys is 2,9mm and hand calculation is 6,9mm (The mass participation is 93% in the ansys model). Is there anything else that I could adjust? or could there be another reason for such deviation?
@@krittikaag, for simple structure like yours, it should match natural frequency. Displacement in modal analysis is virtual displacement hence not worries. Check material details & try to match with simple frequency formula.
Can I get the information regarding the structural dimension, material properties and any other details as I would like to rerun the simulation to make comparison as my practice purpose. Thank you
We did assumptions on dimension for explaining the seismic analysis. So please do assumption at your end and let us know if you are facing any difficulties. thanks
Structural analysis using base isolation in FEA is depends on so many factors and their modeling/idealization is difficult task. It depends on selection on appropriate base isolation, uses & load types, etc. Will upload video on base isolation selection guidelines. You can also refer video for base modeling in ansys: th-cam.com/video/pihYx0a3t-4/w-d-xo.html
You can use APDL script for forces and moment extraction like *get,my_fsumx_event_DW_Left_1_Z,fsum,0,item,fx ....you can repeat this for all forces and moments by changing, fx, fy, fz, mx, my, mz.
It is difficult to enter more than 100 points. You need to filter the data points in excel and use envelope of spectrum values. Remove the repetitive data Frequncy vs accn data. We will upload blogpost on same on our blog soon.
Frequency are closely spaced meaning that while taking data frequently the acceleration changes. If acceleration changes after more cycle than it is far spaced am I right
Please kindly check first part, We had mentioned closely & separated frequency details. Generally modes with closed freq. is function of damping ration & if damping ratio is less than 2%, closely spaced frequency means which are within 10% of each other.
@@rajanarjunsharma6612 I have s successfull solution of this Problem. Example of My script: /NOPR ! Suppress printing of UNDO process /PMACRO ! Echo following commands to log !FINISH ! Make sure we are at BEGIN level /CLEAR,NOSTART ! Clear model since no SAVE found ! WE SUGGEST YOU REMOVE THIS LINE AND THE FOLLOWING STARTUP LINES /input,menust,tmp,'' /GRA,POWER /GST,ON /PLO,INFO,3 /GRO,CURL,ON /CPLANE,1 /REPLOT,RESIZE WPSTYLE,,,,,,,,0 /PREP7 !* ET,1,BEAM189 !* ET,2,MASS21 !* ET,3,MASS21 !* KEYOPT,2,1,0 KEYOPT,2,2,0 KEYOPT,2,3,2 !* KEYOPT,3,1,0 KEYOPT,3,2,0 KEYOPT,3,3,2 !* !* R,1,100, !* !* R,2,200, !* !* !* !* MPTEMP,,,,,,,, MPTEMP,1,0 MPDATA,EX,1,,2e11 MPDATA,PRXY,1,,0.3 MPTEMP,,,,,,,, MPTEMP,1,0 MPDATA,DENS,1,,1e-07 SECTYPE, 1, BEAM, ASEC, , 0 SECOFFSET, CENT SECDATA,2.242e-03,4e-07,0,4e-07,0,1,0,0,0,0,0,0 K, ,,,, K, ,,2,, K, ,2,2,, LSTR, 1, 2 LSTR, 2, 3 TYPE, 1 MAT, 1 REAL, 1 ESYS, 0 SECNUM, 1 LESIZE,ALL,0.1, , , , , , ,1
Dear sir , I have some doubts in seismic analysis , I am trying to do directional combination for seismic analysis, how I can combine three directions. Please help on this. Thanks in advance.
Hello, You can apply in three direction like X, Y & Z axis respective directions. Spectrum is nothing but seismic response in single or multiple axes. Based on spectrum you can select combination like ROSE, CQC, SRSS as mentioned in introduction video.
@@graspengineering9249 Thanks for your response, I am trying to do load combination. For example I am trying to do load combination for Dead Weight load case , Design pressure and Seismic load (x+y+z). Please explain how we can do by using APDL commands in workbench.
You can apply dead load, pressure loads and perform static analysis & then do pre-stress modal and then do response spectrum connected with modal analysis.
@@sabiharekha hi ..did you get the answer for your query . because i am having the same question like how to convert the frequency domain. as per my understanding .. frequency is 1/T (time ) .. we can calculate the frequency value from the time domain value .. please suggest if you get any other way..
thank you for your informative video, upload video for numerical ways to do seismic analysis
Nice explanation sir
Thanks and welcome
Thank you for your video Sir. Could you please display a video for the base isolation of the same above structure?
Welcome. We will check if feasible. Base isolation is vast topic.
Thank you for the informative video. I would like to know how the directional acceleration is higher at the lower floor and it goes on decreasing along the height of the structure?
Welcome !
Thank you for sharing.
Will you explain how to get frequency domain for input as Time history does not work here
Yes, soon
Thanks for informative video.is it possible to combine static structural results with response spectrum?using pre-stressed setting does not seem to sum up the results (VM stress).
You can combine results after getting solution of two different analysis. Check this tutorial, th-cam.com/video/2oLs7ES0hJc/w-d-xo.html
sir please make a video on how to draw geometry in design modeler or discovery
How to evaluate the stresses developed after response spectrum analysis ?
You told in the process flow that these stresses must be included, where should it be included ?
Yes, these seismic stresses need to exctract and compare with allowable stresses or yeild limit of the material.
Why to add Point Mass?
Please explain the reason and methodology to add Point Mass in the simulation.
Point mass is used to attach the mass in the system. The mounting equipment which are not required to model can be idealized using point mass.
We need to give only point mass or we can also provide uniform mass of components to be placed on structure?
On point mass you need to define weight of the equipment's.
sir from where did you acquired the seismic data
Hello Sir, could you elaborate or share any document on calculation of the acceleration with respect to the frequency; that you have used as an input for the response spectrum in ansys at 17:11 in the video. Your help will be of great importance to my research - Thank you
Hello, I had assumed acceleration Vs frequency data for explaination of video. You can refer any relavant standard or will get from manufacturer of the respective equipment based on seismic zone.
@@graspengineering9249 Thank you replying. However, the results of my hand calculations as per IS 1893 are different as compared to the simulation on ansys, Though I have input the acceleration values as given in IS and put in a scale factor of 9806.6 (my model is in mm), I have turned on large deflections and perform using SRSS method. It will be helpful if you could also share the possible reasons for this great deviation between the results, (Does that have to do with the mass and stiffness matrix in Ansys)?
@@krittikaag Hello , First please check the natural frequency from modal analysis & with hand calculations. Also check mass participation is more than 90 % or not.
@@graspengineering9249 Thank you for being so responsive. It is strange but the model is working for a building with 2 degree of freedom, my calculations are matching ansys output. However, the frequency and displacement is not matching for 3 DOF using the same setup and same calculation procedure. Ansys is giving a frequency (mode 1) of 14,5Hz and calculation shows 10Hz. Thus, displacement as per ansys is 2,9mm and hand calculation is 6,9mm (The mass participation is 93% in the ansys model). Is there anything else that I could adjust? or could there be another reason for such deviation?
@@krittikaag, for simple structure like yours, it should match natural frequency. Displacement in modal analysis is virtual displacement hence not worries. Check material details & try to match with simple frequency formula.
how can we perform same analysis in APDL ( I mean coupling analysis). Please make video on APDL coupling analysis. Thanks
You can refer video of APDL in description link for coupling analysis.
Can I get the information regarding the structural dimension, material properties and any other details as I would like to rerun the simulation to make comparison as my practice purpose. Thank you
We did assumptions on dimension for explaining the seismic analysis. So please do assumption at your end and let us know if you are facing any difficulties. thanks
Hello there, are the acceleration values already given when uploading the data for the response spectrum ? Or we need to calculate them?
Hi, we assume the acceleration values for simulation purpose. In actual, you should get this spectrum values from respective geography zonal area.
@@graspengineering9249 thank you so much !
How to made
this geometry exacltly
SIR please give me some guidelines regarding structural analysis using base isolation in ansys
Structural analysis using base isolation in FEA is depends on so many factors and their modeling/idealization is difficult task. It depends on selection on appropriate base isolation, uses & load types, etc. Will upload video on base isolation selection guidelines. You can also refer video for base modeling in ansys: th-cam.com/video/pihYx0a3t-4/w-d-xo.html
@@graspengineering9249 ok sir
Sir can u pls explain how we will extract the forces on the supports?
You can use APDL script for forces and moment extraction like *get,my_fsumx_event_DW_Left_1_Z,fsum,0,item,fx ....you can repeat this for all forces and moments by changing, fx, fy, fz, mx, my, mz.
Hi sir, is it possible to increase the allowable data points for response spectrum (sprs)? The ansys limit is 100points.
It is difficult to enter more than 100 points. You need to filter the data points in excel and use envelope of spectrum values. Remove the repetitive data Frequncy vs accn data. We will upload blogpost on same on our blog soon.
Frequency are closely spaced meaning that while taking data frequently the acceleration changes. If acceleration changes after more cycle than it is far spaced am I right
Please kindly check first part, We had mentioned closely & separated frequency details. Generally modes with closed freq. is function of damping ration & if damping ratio is less than 2%, closely spaced frequency means which are within 10% of each other.
I cant find Beam results (stress,bending moment,normal force etc.) in Response Spectrum, please,help me,where are they?
You need to keep beam results option ON in the analysis setting.
@@graspengineering9249 I cant find this option in analysis setting of Response Specrtum In output controls.Maybe,should I look elsewhere?
I have found this option,thanks
Hello,1.Сan you perform the response spectrum analysis in APDL using GUI?
2.Can you explain how to perform beam results in Response Spectrum Analysis?
Okay
hi.. How did you perform response spectrun analysis in APDL using GUI? can you please share with me......
@@rajanarjunsharma6612 I have s successfull solution of this Problem. Example of My script:
/NOPR ! Suppress printing of UNDO process
/PMACRO ! Echo following commands to log
!FINISH ! Make sure we are at BEGIN level
/CLEAR,NOSTART ! Clear model since no SAVE found
! WE SUGGEST YOU REMOVE THIS LINE AND THE FOLLOWING STARTUP LINES
/input,menust,tmp,''
/GRA,POWER
/GST,ON
/PLO,INFO,3
/GRO,CURL,ON
/CPLANE,1
/REPLOT,RESIZE
WPSTYLE,,,,,,,,0
/PREP7
!*
ET,1,BEAM189
!*
ET,2,MASS21
!*
ET,3,MASS21
!*
KEYOPT,2,1,0
KEYOPT,2,2,0
KEYOPT,2,3,2
!*
KEYOPT,3,1,0
KEYOPT,3,2,0
KEYOPT,3,3,2
!*
!*
R,1,100,
!*
!*
R,2,200,
!*
!*
!*
!*
MPTEMP,,,,,,,,
MPTEMP,1,0
MPDATA,EX,1,,2e11
MPDATA,PRXY,1,,0.3
MPTEMP,,,,,,,,
MPTEMP,1,0
MPDATA,DENS,1,,1e-07
SECTYPE, 1, BEAM, ASEC, , 0
SECOFFSET, CENT
SECDATA,2.242e-03,4e-07,0,4e-07,0,1,0,0,0,0,0,0
K, ,,,,
K, ,,2,,
K, ,2,2,,
LSTR, 1, 2
LSTR, 2, 3
TYPE, 1
MAT, 1
REAL, 1
ESYS, 0
SECNUM, 1
LESIZE,ALL,0.1, , , , , , ,1
LMESH,ALL
TYPE, 2
REAL, 1
E, 2
REAL, 2
E, 42
ANTYPE,2
!*
!*
MODOPT,LANB,2
EQSLV,SPAR
MXPAND,2,,,YES
LUMPM,0
PSTRES,0
!*
MODOPT,LANB,2,0,0, ,OFF
FINISH
/SOL
DK,1, ,0, ,0,ALL, , , , , ,
DL,ALL, ,UZ,0
/STATUS,SOLU
SOLVE
/OUT,SCRATCH
*GET,MODC_1,MODE,1,MCOEF
*GET,MODC_2,MODE,2,MCOEF
*GET,PFAC_1,MODE,1,PFACT
*GET,PFAC_2,MODE,2,PFACT
FINISH
/OUT,SCRATCH
/SOLUTION
ANTYPE,SPECTRUM ! PERFORM SPECTRUM ANALYSIS
SPOPT,SPRS,2,1,1 ! SINGLE POINT RESPONSE SPECTRUM ANALYSIS
CQC,0.001,DISP, ,
SVTYPE,3 ! DISPLACEMENT RESPONSE SPECTRUM
DMPRAT,0.02
FREQ,0.874,2.683,0,0,0,0,0,0,0
SV,0,0.1053,0.034,
SED,1,0,0
OUTPR,NSOL,ALL
OUTRES,ALL,ALL
SOLVE
FINISH
/POST1
/INPUT,,mcom
!*
/EFACET,1
PLNSOL, U,X, 0,1.0
can we do fatigue analysis in this module?
Yes you can
@@graspengineering9249 can you send a pic or guide me to the fatigue tool option?
Dear Sir, if i use Rose combination method, ¿ don't i need to define damping parameters (alfa,beta and damping ratio)?
Yes, for CQC method only you will need to define damping parameters. While if you have damping parameters, you can use for ROSE method too.
@@graspengineering9249 Sorry sir, ¿then Dont i need damping parameters for rose combination methods?
@@bastianren Damping Parameter is assumptions based on Equipment & loads. If you don't have then okay, it will be more conservative analysis approach.
Can you send the project wbpz file
Dear sir , I have some doubts in seismic analysis , I am trying to do directional combination for seismic analysis, how I can combine three directions. Please help on this. Thanks in advance.
Hello, You can apply in three direction like X, Y & Z axis respective directions. Spectrum is nothing but seismic response in single or multiple axes. Based on spectrum you can select combination like ROSE, CQC, SRSS as mentioned in introduction video.
@@graspengineering9249 Thanks for your response, I am trying to do load combination. For example I am trying to do load combination for Dead Weight load case , Design pressure and Seismic load (x+y+z). Please explain how we can do by using APDL commands in workbench.
You can apply dead load, pressure loads and perform static analysis & then do pre-stress modal and then do response spectrum connected with modal analysis.
@@graspengineering9249 Thanks you for your help
Hello sir which software is this
ANSYS !
If we want to take the real earthquake data, there is time history data but no frequency data. how can we do that?
Hello & Greetings ! You need to convert time domain into frequency domain.
@@graspengineering9249 can you help me to do this? Can you give me a video? I need urgently for my research work.please..
@@sabiharekha hi ..did you get the answer for your query . because i am having the same question like how to convert the frequency domain. as per my understanding .. frequency is 1/T (time ) .. we can calculate the frequency value from the time domain value .. please suggest if you get any other way..
@@kandamurugesan143 ......did you get the answer
why is the point mass value 100 kg?
In relastic frame may have some components, which we assumed by point mass. It is used for explanation purpose.