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Two-way slab with simply supported edges

Bending moments in both directions of a two-way slab from the moment coefficients, and the steel in each direction. Reference: IS 456:2000 Annex D (D-2), Table 27.

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# Data
l_x := 4 m
l_y := 6 m
l_y/l_x =
D := 160 mm
d_x := 130 mm
d_y := 120 mm
f_ck := 25 MPa
f_y := 500 MPa
w_u := 1.5*((25 kN/m^3)*D + 1.5 kN/m^2 + 4 kN/m^2) =

# Moment coefficients
# For l_y/l_x = 1.5 with corners not held down, Table 27 gives the two coefficients below.
alpha_x := 0.104
alpha_y := 0.046

# Moments per metre width
b := 1000 mm
M_x := alpha_x*w_u*l_x^2*b = kN*m
M_y := alpha_y*w_u*l_x^2*b = kN*m

# Steel
A_x := 0.5*f_ck/f_y*(1 - sqrt(1 - 4.6*M_x/(f_ck*b*d_x^2)))*b*d_x = mm^2
A_y := 0.5*f_ck/f_y*(1 - sqrt(1 - 4.6*M_y/(f_ck*b*d_y^2)))*b*d_y = mm^2
A_min := 0.0012*b*D = mm^2

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