Spacing of confining reinforcement for column as per IS13920 2016

 Applies To 
 Product(s):STAAD Advanced Concrete Design
 Environment: N/A
 Area: Concrete Design
 Subarea: Column Design
 Original Author:Abhisek Mandal
Bentley Technical Support Group

Refer attached snap from IS13920. Max spacing limit for confining reinf is 100mm in this case. RCDC output shows spacing of 125mm, is this correct?

The clause you are referring to has been amended along back. As per Amendment no 1 to IS13920 :2016 the 3 criteria have been replaced with a single one. Please see attached snap. As per amendment maximum spacing will be 6 times the smallest longitudinal reinforcement. Here, dia of longitudinal reinforcement is 25mm. So, maximum allowed is 6 x 25mm = 150mm. So, spacing 125mm is okay.

Along with that as per clause 8.1 (c) [in amendment 7.6.1 (c)] we need to fulfill the Ash criteria. Now, in some cases the calculated Ash with maximum allowable Sv does not satisfy the required Ash. So, in those cases a less Sv will satisfy the requirement and hence spacings are reduced in some cases.