While doing design of beam using Staad file interface at each level selected beams need to be design as per Staad design envelope.
1) Along X-direction grid design will be one envelope.
2) Along Z-direction grid design will be second envelope.
3) Along X/Z-direction grid design will be third envelope. And so on....
Along there will be limited beam number RCDC do the design of beams/column with interface with staad model, if those number increase more then 10 nos. then RDCD program will not work,