Applies To
	Product(s):	STAAD Advanced Concrete Design
	Version(s):	Connect Edition
	Environment:
	Area:	Concrete Design
	Subarea:	Slab Design
	Original Author:	Abhisek Mandal, Bentley Technical Support Group

 We are designing slab in RCDC but some slab portion is not considered for design which are shown by black screen between slab.

RCDC identifies the slab based on closed polygons. The close polygons are identified based on the periphery beams.  

In your case, beams B13 and B29 are overlaps each other. Due to overlapping of beams there are no close polygons are identified.

We would suggest you intersect these beams as shown below. This will not impact analysis of the structure.

After intersecting the beams, RCDC is now able to read the slab properly,