ACI 318-19 Section 25.3.1 specifies standard hook geometries for reinforcing bars. The bend diameter (6d_b) and hook extension lengths vary based on hook angle and rebar size.
| Hook Angle | Description | Bend Diameter | Hook Length | Reference |
|---|---|---|---|---|
| 90° Hook | Standard hook for beam and column ties | 6d_b (for d_b ≤ 20mm) | min 12d_b | ACI 318-19, Sec 25.3.1 |
| 135° Hook | Seismic hook for special moment frames | 6d_b (for d_b ≤ 20mm) | min 12d_b | ACI 318-19, Sec 25.3.1 |
| 180° Hook | Standard hook for beam and column longitudinal bars | 6d_b (for d_b ≤ 20mm) | min 4d_b | ACI 318-19, Sec 25.3.1 |
| Rebar | d_b (mm) | Bend Pin (6d) | 90° Hook (12d) | 135° Hook (12d) | 180° Hook (4d) |
|---|---|---|---|---|---|
| #10 (M10) | 9.5mm | 57mm | 114mm | 114mm | 38mm |
| #13 (M13) | 12.7mm | 76mm | 152mm | 152mm | 51mm |
| #16 (M16) | 15.9mm | 95mm | 190mm | 190mm | 64mm |
| #19 (M19) | 19.1mm | 114mm | 229mm | 229mm | 76mm |
| #22 (M22) | 22.2mm | 133mm | 267mm | 267mm | 89mm |
| #25 (M25) | 25.4mm | 152mm | 305mm | 305mm | 102mm |
| #29 (M29) | 28.7mm | 172mm | 343mm | 343mm | 115mm |
| #32 (M32) | 32.3mm | 194mm | 387mm | 387mm | 129mm |
| #36 (M36) | 35.8mm | 215mm | 430mm | 430mm | 143mm |