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Response Spectrum Analysis

Experimenter
Experimenter

I tried running the Response Spectrum Analysis example but get no errors and no output results.  Is there something missing now in v11.11 or the example description?  One thing that is odd is that the output dialog box SUPORT DOF is in a different box by default than the example.

 

(Earlier NASTRAN versions had difficultly with with this method for shock.  MSC NASTRAN has  a fixed new version that now works.)

5 REPLIES 5

Re: Response Spectrum Analysis

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Comet,

If you are interested in Response Spectrum Application (not Generation!!) Analysis here you are a tutorial I wrote in my website explaining step-by-step how to run with FEMAP & NX Nastran:

http://www.iberisa.com/soporte/femap/dinamico/response_spectrum_4story.htm

 

4story_femodel.png

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Response Spectrum Analysis

Experimenter
Experimenter

Hi,

 

Thanks for the input. I too have the similar proble. When i try to replicate the model as said in the wb address i could able to run. But i need to analyse the model using density. Can you please let me know how to run the model with density ( no Mass elements). I could able to run, but the results are not correct.

 

Thanks in advance

Re: Response Spectrum Analysis

Experimenter
Experimenter

Hi Blas

 

I have followed your example setting a up shock response analysis, however, upon varying the modal damping parameter between 2% and 20% makes no difference to von Mises stress values or acceleration. I have attached a snap of my setup. Is all in order there? 

Re: Response Spectrum Analysis

Phenom
Phenom

@David4 wrote:

Hi Blas

 

I have followed your example setting a up shock response analysis, however, upon varying the modal damping parameter between 2% and 20% makes no difference to von Mises stress values or acceleration. I have attached a snap of my setup. Is all in order there? 


That is SRS analysis, ie the SDAMP is used to retrieve the proper SRS in the DTI,SPECSEL.  An SRS is associated with a particular value of Q.  If you had a different TABLED1 for Q=25 and Q=2.5, properly called by respective DTI, then you would see a difference in response.

Re: Response Spectrum Analysis

Experimenter
Experimenter

Dear Mr. Molero,

I have studied your model description very carefully. I have some questions regarding the example of multistory frame.

1. What have I to do if I have 3D structure and the dynamic load is seismic ecxitation represented by 3 different response spectra - for each direction and all 3 are acting  simultaneously? How could I make both - modal and directional combinations using SRSS method?

2. If I have for example multistory building on foundation plate and the soil-structure interaction is represented by spring elements how am I supposed to use the large mass method in order to calculate the  internal stresses in the base matt (foundation plate) due to seismic ecxitation? The input will be free field response spectrum - one for both horizontal directions and other for the vertical direction.

 

Thanks in advance vor your advice!