b=250//width, in mm
d=500//effective depth, in mm
Mu=165//in kN-m
top_cover=50//in mm
fck=15//in MPa
fy=250//in MPa
Xc=0.531*d//in mm
Mulim=0.149*fck*b*d^2/10^6//in kN-m
Ast1=round(0.36*fck*b*Xc/0.87/fy)//in sq mm
M1=Mu-Mulim//in kN-m
fcc=0.446*fck//in MPa
fsc=0.87*fy//in MPa
Asc=round(M1*10^6/(fsc-fcc)/(d-top_cover))//in sq mm
Ast2=round((fsc-fcc)*Asc/0.87/fy)//in sq mm
Ast=Ast1+Ast2//in sq mm
mprintf("Compression steel = %d sq mm\nTension steel = %d sq mm",Asc,Ast)