This standard provides comprehensive guidelines for the correct cutting, bending, and fixing of steel reinforcement bars used in reinforced concrete. It specifies the standard dimensions for hooks, bends, stirrups, and ties, along with permissible tolerances, forming the basis for Bar Bending Schedules (BBS).
Provides recommendations for the correct methods of detailing reinforced concrete members in structures.
Quick Reference Values
standard u hook allowance9d (per hook)
standard 90 degree bend allowance5d
cutting length tolerance± 25 mm
bending dimension tolerance± 10 mm
minimum internal radius mild steel2d
minimum internal radius hysd bars4d
Key Formulas
Cut Length of Bar with 2 U-Hooks = L + 18d (where L is straight length and d is bar diameter)
Practical Notes
Always account for bend elongations (deductions) when calculating cut lengths to prevent the fabricated bars from being oversized.
Use the correct mandrel diameter during bending to avoid micro-cracking at the bends, especially for HYSD and TMT bars.
BBS detailers must follow these standard dimensions unless overridden by specific seismic detailing requirements (like IS 13920).