pl help/.....this error comes for me , while designing in concrete design... The safety of the beam against lateral buckling is in doubt in span 1 in persistent situations.........................

Please attach the .std, .Rei_Concrete and .Rei_Concrete_Link files of that model for the investigation.

New folder.zipthe staad model

This warning is to do with the Cl. 5.9 of the code which checks for the lateral instability if a cross section is too slender. Could be during construction or while transporting. This is simply a warning that checks for the following and can be ignored by the user if he/she is happy that this will not be critical.