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Maximum bar spacing for crack control

Largest bar spacing that limits crack widths to 0.3 mm without calculation, from the steel stress. Reference: EN 1992-1-1 7.3.3, Table 7.3N.

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# Inputs
f_yk := 500 MPa
g_k := 25 kN/m
q_k := 15 kN/m
psi_2 := 0.3
A_s.req := 1250 mm^2
A_s.prov := 1473 mm^2

# Steel stress under quasi-permanent load
ratio := (g_k + psi_2*q_k)/(1.35*g_k + 1.5*q_k) =
sigma_s := f_yk/1.15*ratio*A_s.req/A_s.prov = MPa

# Maximum spacing for w_k = 0.3 mm
s_max := interp(sigma_s/(1 MPa), [160, 200, 240, 280, 320, 360], [300, 250, 200, 150, 100, 50])*1 mm = mm

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More Eurocode 2 sheets on serviceability

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