Minimum Flexural Reinforcement As,min (ACI 318-19 9.6.1.2)
As,min = max(3 sqrt(f'c)/fy, 200/fy) x bw x d, so the beam does not fail suddenly at first cracking. 4000 psi, Grade 60, 12x20 -> 0.80 in^2 (200/fy floor governs); at 5000 psi the sqrt term governs, 0.85 in^2. A design aid; the engineer of record's stamped design governs.
Formula and source
ratio = max(3 sqrt(f'c)/fy, 200/fy); As,min = ratio x bw x d.
The ACI 318-19 9.6.1.2 minimum flexural reinforcement, by name.
Audience
This tile is built for trades and the adjacent professions in the Carpentry and Construction group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.