After analysis, while starting the design Etabs give this error only while performing concrete frame design. Any one who knows the solution reply to it..
I had this problem during my project. It had been a headache for me for 2 days. This problem arised due to modeling by using beam auto option or column auto option. When ever this problem comes firstly check the modeling. If you have modeled using auto option then replace those beams and columns by any user defined beams.
Thanks