[I]Export spectral analysis results from ETABS to SAFE[/I] 1

[ingemor]

A couple of days ago I posted in Murali27’s “Export from Etabs” thread in the SAFE forum more or less the following:

I have heard that there is another trick to solve the problem of exporting spectral analysis results from Etabs to Safe besides using equivalent static seismic load cases. I think that the idea behind the trick could be something like this:

1.) Run a static quake and the required spectrum analysis in the same Etabs model.

2.) Analyze the different output formats for both results in exportable Safe.f2k text file.

3.) Extract the spectrum analysis results from Safe.f2k text file.

4.) Change and match format of the spectrum analysis results to the format produced by ETABS for static quake analysis (eliminate excess data).

5.) Re-incorporate the spectral results in the modified format into the SAFE .f2k file.

6.) Delete the static quake results from that file.

7.) Import the modified f2k file to SAFE and run it.

I understand that the changing and matching format process is tedious but, again, I have heard that it can be expedited by using Excel.

I’ll like to know comments and recommendations both from those who have used this trick or a similar one, as well as from those who are interested in try it out. I’ll be trying it out in couple of weeks.

Regards
ingemor

 

[DENSAL55]

exporting spectral analysis results from Etabs to Safe for slab foundation analysis or beam foundations analysis has no sens because results given by spectral analysis are always in absolute value this means that they are always positive or if multiply by -1 always negative.And by this way it doen't give the behavior of overturning effect.

 

[DENSAL55]

There is anothere way to solve this problem.Make spectrale analysis then take sheare story result and there position, and make a static analysis with the previous sheare story as static force in the new analysis at there respective position, the reaction given at the base of the structure is given with there sign, and at this point we can use this result for safe analysis or othere one.

 

[ingemor]

Thank you DENSAL55 for your comments and recommendation.

I have limited knowledge of dynamic analysis, nevertheless I’m documenting my self to digest the reason you posted that makes the proposed trick not viable.

As for your recommendation, its is clear and I’ll try it out.

Regards and thanks again.
ingemor

 

[Murali27]

Thanks DENSAL55 & Ingemor for your thoughts. Spectral story shears are considering the contribution from all the modes. Hence, can these story shears be applied as a static force? I will also do some comparison.

Thanks again
Murali27

 

[DENSAL55]

It's what i say .A combination or SRSS give always an absolute value and we can't use this result for a calculation of slabe fondation or beam fondation it can't give the overturning effect . So we can use an equivalent static model by using story shears applied as static forces.

 

[DENSAL55]

To confirm what i said before, you can see that Etabs use the Story shears value to calculate oveturning moment Mx and My.
at differents levels and at the base of the structure.this overall moments is equivalents in value to those you obtain by the equivalent static case using story shears.