Response spectrum - SRSS - negative values

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  • Last Post 06 March 2018
d.giaccone posted this 10 February 2018

Dear all, I’m running a spectrum analysis with Ansys, and I found a stranger behaviour in final results. modeled a simple column, 30x30x300 cm, subject to its own load. I run a modal analysis, and then a response spectrum, using 4 shape modes and a SRSS combination mode. analysed Ansys results: as regard the deformation and the normal stress, Ansys results correspond with manually ones; as regard principal stress, on the contrary, I don’t obtain the same results. Moreover, I noticed that Ansys gives not only positive but also negative values, that is impossible according to the definition of the SRSS combination method itself. I tried also to repeat the analysis using another combining method (CQC) but the problem still exists. What can be the cause? Thankyou.

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peteroznewman posted this 10 February 2018

It could help if you would attach the archive of your project to your post and say which version of ANSYS you are using.

d.giaccone posted this 10 February 2018

I'm using ANSYS 18.0. How can I attach the file?

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peteroznewman posted this 10 February 2018

In Workbench, save the project, then File, Archive... and create a .wbpz file.  If that file is < 120 MB, you can attach it using the Attach button on any of your posts.

If the file is > 120 MB, click on Model, Clear Generated Data, then save and archive to get a smaller file. Don't include results.

d.giaccone posted this 10 February 2018

Ok, it was really a size problem 

Attached Files

peteroznewman posted this 12 February 2018

I have downloaded your model and solved it, now I need some time to study RS analysis as your question is deep.

d.giaccone posted this 12 February 2018

Ok, I will wait... thank you

d.giaccone posted this 16 February 2018

Hi peteroznewman, you got some news?

peteroznewman posted this 16 February 2018

Sorry, I have not had time to study this yet. I plan to do some this weekend.

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d.giaccone posted this 06 March 2018

Hi everybody, you got some news about my trouble? Do I deduce that there is a mistake in Ansys algorithm?

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