FE Model Updating in STRAND7 using MATLAB code and API module

[cowled]

Hi there. This is my first post on this forum.

I have designed and constructed a small scale steel through truss bridge (8.5m x 2.5m x 1.0m) and done some Modal Testing and Analysis to obtain the natural frequencies and mode shapes. Now I am trying to update my Strand7 model of the structure to match the results of my modal analysis. I have used Strand7 quite a bit over the years, however, I have quickly come to realise that this "FE model updating" task is going to be a very tedious exercise if I have to manually update the parameters. I have around 100 parameters that can be varied, so the possible combinations of solutions is going to be huge.

I have discovered that Strand7 has an API module which allows the user to write a program in Matlab that can do a whole raft of cool things like: 1) open a Strand7 model; 2) vary parameters; 3) run solvers; 4) output results; 5) calculate Modal Assurance Criterion (i.e., a scalar representation of the goodness of fit between Experimental results and FE results); 6) save MAC values; then return to step 2 and repeat the process.

Problem is, I've never done anything quite like this and I'm getting error messages when trying to run the Strand7 examples. I have to admit to being a better structural engineer than a computer programmer.

Has anyone out there used the Strand7 API module with Matlab code for the purpose of Model Updating? If so, I might like to ask how you did it and whether you'd be comfortable sharing your knowledge.

Thanks in advance,

Craig Cowled
Structural Engineer, Queensland University of Technology.

 

[IDS]

I don't know Matlab, but I make regular use of the Strand7 API using VBA with Excel. I use it both for modifying models and reading results straight into the spreadsheet.

The link below is to an article and download file (with open source code) which provides Excel UDFs linking to all the API node related functions. I would be happy to discuss this or any other aspects of the API usage, but I can't help with the Matlab side of things.

http://newtonexcelbach.wordpress.com/2012/02/19/strand7-api-getnode-functions/

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[cowled]

Doug, thank you very much for the quick reply. I've seen your work before. Was particularly interested in the work you did on optimising super-T girders.

Thank you for providing that link. The process in Excel seems to be quite similar to that in Matlab. The issues I'm having at the moment seem to be Matlab problems rather than Strand7 problems. I'll persist some more with Matlab because all my analysis is done in Matlab. If I'm unsuccessful in Matlab, I'll have a serious look at Excel.

Do you know whether it is possible to automate multiple iterations in Excel?

Thanks,

Craig.

 

[IDS]

Yes, that is one of the main things I use it for. You can read results, read and change any element attribute, adjust or create new load iterations, and restart from any completed iteration.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/