The link element can not be imported into OSN except the name of them. If the definition is missing,the s2k file cannot be imported.That is the reason that I believe at the beginning that OSN cannot recognize them and the import aborts.
The nonprismatic section cannot be imported,which makes the import failed.
So I calculate the mean sections to take the place of nonprismatic sections and lumped mass at joints,revising the material mass density with zero， for OSN could calculate linear mass density for element definition from s2k file. I don’t think OSN could calculate the volume or mass of the nonprism element.
Now，the mode periods and shapes from OSN are almost the same as those from SAP2000.
Now I wonder if I could get the parameters about mode shape participation.How can I check the mode shape from different model？
Thanks for your help,Andreas! Your advice gave me great inspirations and pushes .I really appreciate it!