Combined stress (compression and bending)

Input

Compressive load

P

Cross-sectional area

A

Beam length

L

Section modulus (compression side)

Z_c

Section modulus (tension side)

Z_t

Allowable compressive stress

f_c

Allowable bending stress

f_b

Allowable tensile stress

f_t

Bending moment

M

Average compressive stress

\sigma_c

Bending stress (compression side)

\sigma_{bc}

Bending stress (tension side)

\sigma_{bt}

Combined stress check (compression side)

f_{cc}

Allowable combined stress check (tension side)

f_{tc}

Notes

Based on 6.1 "Compressive force and bending moment" of the AIJ Standard for Allowable Stress Design of Steel Structures (2019): Eq. (6.1) on the compression side and Eq. (6.2) on the tension side.
Work out whichever allowable stresses apply and enter them here. The allowable compressive stress f_c comes from 5.1(3) of the same Standard, the allowable bending stress f_b from 5.1(4) and the allowable tensile stress f_t from 5.1(1). The Compressive stress and Bending stress pages on this site will give you those.
Take the absolute value of each stress (proviso to 6.1 of the same Standard).
Where the Standard writes "stress intensity", this page writes simply "stress".