Applies To
	Product(s):	STAAD Advanced Concrete Design
	Version(s):	All
	Environment:	N/A
	Area:	Concrete Design
	Subarea:	Column & Shear Wall
	Original Author:	Suvadeep Acharjee Bentley Technical Support Group

On what basis does RCDC perform the Joint shear check based on the Aspect ratio of vertical member as per Clause 7.1.2 IS:13920 - 2016 & Amendment no.1 - 2017?

As per clause 7.1.2 IS;13920 - 2016, the vertical members of structure whose B/D >= 0.4 (or D/B <= 2.5), shall be designed as per requirements of Clause 9.

The first print of IS;13920 - 2016, 'Clause 8' talks about 'special confining reinforcement'. Later in Amendment no.1 - 2017 to IS;13920 - 2016 , this clause was renamed as 7.6. Hence, the old clause 9 now automatically becomes 8 and clause 10 (which is for shear walls) becomes 9.

Further, in the same amendment, they have mentioned that 0.45 in 7.1.2 should be replaced by 0.4. With this background, one can interpret 7.1.2 as below - It is preferred to provide D/B as 2.5 or less (B/D 0.4 or more) for columns. In clause for walls it is very clearly mentioned that D/B should be more than 4. Also, 

So, for D/B between 2.5 and 4, the behavior is in between and should be avoided. However, if one has to use these ratios then those members can be designed as walls as per clause 9, and can be done in RCDC by changing the D/B ratio in Design Settings form.