I get this error while importing my staad file into staad advanced concrete design, earlier there was no error now every model while importing into staad rcdc gives this error "columns are missing". I found a thread where someone said they did some settings change in os which I didn't understand.
I works after I restart the system, next time if it occurs again I'll try that changing folder location method.thanks for your reply sir
Can you please copy the .std file to a new folder and then run the file. After that try importing it in RCDC and let me know the outcome.