Marius -
We use the Engineering International Spreadsheets in our office. As an other lister has pointed out it is recommended that you check it. I had some issues with the Special Concentric Brace Frame connection design spreadsheet and I contact Mr. Li. We were able to successfully work it out. It is good that he is responsive. Overall it is a good set of spreadsheets.
Andre J. Sidler, S.E.
Quantum Consulting Engineers
Seattle, WA