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One-way slab design

Loads, bending moment, main and distribution steel and bar spacing for a simply supported one-way slab. Reference: IS 456:2000 Cl. 24, 26.3.3, 26.5.2.

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# Data
l := 3.5 m
D := 150 mm
cover := 20 mm
phi := 10 mm
d := D - cover - phi/2 =
f_ck := 25 MPa
f_y := 415 MPa

# Loads per metre width
b := 1000 mm
g_sw := (25 kN/m^3)*D =
g_fin := 1.0 kN/m^2
q := 3 kN/m^2
w_u := 1.5*(g_sw + g_fin + q)*b = kN/m
M_u := w_u*l^2/8 = kN*m

# Steel
M_u <= 0.138*f_ck*b*d^2 =
A_st := 0.5*f_ck/f_y*(1 - sqrt(1 - 4.6*M_u/(f_ck*b*d^2)))*b*d = mm^2
A_st.min := 0.0012*b*D = mm^2
s := min(1000 mm*pi/4*phi^2/max(A_st, A_st.min), 3*d, 300 mm) = mm

# Distribution steel
A_dist := 0.0012*b*D = mm^2
s_dist := min(1000 mm*pi/4*(8 mm)^2/A_dist, 5*d, 450 mm) = mm

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