Composite Beam Flexural Strength (AISC 360-22 I3)
PNA-in-slab composite moment: C = As Fy, a = C/(0.85 f'c be), Mn = C(d/2 + tslab - a/2), phi Mn = 0.90 Mn. As 8.0, Fy 50, d 16, slab 4, be 90, f'c 4 -> C 400 kip, a 1.31 in, phi Mn 340 kip-ft; a narrow be 24 pushes a past the slab and flags PNA-in-steel. The engineer of record governs.
Formula and source
C = As Fy; a = C / (0.85 f'c be) [require a <= tslab]; Mn = C(d/2 + tslab - a/2); phi Mn = 0.90 Mn.
AISC 360-22 §I3.2a composite beam flexural strength with the plastic neutral axis in the slab, 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.