Ax, Ay: Area of steel (in²) longitudinal and transverse of the welded-wire reinforcement (WWR-PCI 15.5, or equivalent).
d, usually = h-2in,
λ =1.0 ACI 8.6 for normalweight concrete,
μ=1.4 for ACI, =3.4 for PCI book,
Φt,Φv,Φc,Φco see ACI 318-808 9.3.2.3, or subsequent ACI book versions.