read the result
Size the internal force couple before choosing bars.
This inverse screen starts with a design moment and solves for the smaller mathematical tension-force root. It keeps the compression-block depth and neutral axis visible so a surprisingly large steel area is not mistaken for a normal bar arrangement.
Governing relationships
The required nominal moment is Mn,req = Mu / φ. With T = Asfy and a = T / (α1fc'b), the equation Mn = T(d - a/2) is solved for T and then divided by fy.
What still needs a full design
- Minimum and maximum reinforcement, ductility, strain limits, compression steel, shear, torsion, anchorage, development, laps, cover, spacing, crack control, and serviceability remain separate checks.
- The stress-block factors, resistance factor, material strengths, effective depth, and factored moment must follow the selected project code and design basis.
- Convert the theoretical area into a constructible bar arrangement and re-run the capacity check using the provided bars.