Shrinkage and Temperature Reinforcement (ACI 318-19 24.4)
Minimum shrinkage/temperature steel perpendicular to the main bars in a one-way slab.
Example
You enter
- Slab thickness h (in) 6
- Design strip width b (in, default 12) 12
- Reinforcement grade (ksi) 60
You get
- Reinforcement ratio 0.0018
- Minimum area As,min = ratio x b x h 0.130 in^2 per strip
- S max (in) 18
Details, formula, and sources
Ratio 0.0018 (Grade 60) or 0.0020 (Grade 40/50), As,min = ratio x b x h, spacing <= min(5h, 18 in). A 6 in slab, Grade 60 -> 0.130 in^2/ft, 18 in max (about #4 at 18). A design aid; the engineer of record's stamped design governs.
ratio = 0.0018 (Grade 60) or 0.0020 (Grade 40/50), never below 0.0014; As,min = ratio x b x h; s_max = min(5h, 18 in).
The ACI 318-19 24.4 shrinkage and temperature reinforcement provisions, by name.
ACI 318 is readable free through the ACI online reading room at concrete.org; the 24.4 shrinkage-and-temperature provisions are in the published code.
Estimate. AHJ and licensed professional govern.
Field names used by the API: h_in, b_in, grade_ksi, ratio, as_min_in2, s_max_in
- Minimum ratio 0.0018 Grade 60, 0.0020 Grade 40/50, floor 0.0014ACI 318-19 24.4.3.2
- Minimum area As,min = ratio x b x h per stripACI 318-19 24.4.3.2
- Spacing limit s_max = min(5h, 18 in)ACI 318-19 24.4.3.3