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Dog-legged staircase flight

Loads on plan from the waist slab, steps and finishes, design moment and steel of a stair flight spanning between landings. Reference: IS 456:2000 Cl. 33.

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# Geometry
R := 150 mm
G := 300 mm
t := 160 mm
l := 3.9 m
d := t - 25 mm =

# Loads on plan per metre width
w_waist := (25 kN/m^3)*t*sqrt(R^2 + G^2)/G =
w_steps := (25 kN/m^3)*R/2 =
w_fin := 1 kN/m^2
q := 3 kN/m^2
w_u := 1.5*(w_waist + w_steps + w_fin + q) = kN/m^2

# Moment and steel
b := 1000 mm
f_ck := 25 MPa
f_y := 415 MPa
M_u := w_u*b*l^2/8 = kN*m
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_dist := 0.0012*b*t = mm^2

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More IS 456 sheets on stairs and walls

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