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Classification of an I-section in bending

Width-to-thickness ratios of the outstand flange and the web of a rolled I-section against the class limits. Reference: EN 1993-1-1 5.5, Table 5.2.

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# Material
f_y := 355 MPa
epsilon := sqrt(235 MPa/f_y) =

# Section
# IPE 300 (typical published values; check against your section tables):
h_s := 300 mm
b_f := 150 mm
t_w := 7.1 mm
t_f := 10.7 mm
r_s := 15 mm

# Compression flange (outstand)
c_f := (b_f - t_w - 2*r_s)/2 = mm
c_f/t_f =
c_f/t_f <= 9*epsilon =
# Up to 9 epsilon the flange is Class 1, up to 10 epsilon Class 2, up to 14 epsilon Class 3.

# Web in bending
c_w := h_s - 2*t_f - 2*r_s = mm
c_w/t_w =
c_w/t_w <= 72*epsilon =
# Up to 72 epsilon the web is Class 1, up to 83 epsilon Class 2, up to 124 epsilon Class 3. Both TRUE: the section is Class 1.

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