European channel section-plastic section modulus calculation

[850R]

Hello all,

I have a question about calculating the plastic section modulus of a channel section.
If you look at the European channel section tables for UPN 300, the Wpl_z is 130cm^3
When I calculate it, it comes out to be 144cm^3
I've attached the table and can attach my calcs as well if I get any response here.
Thank you in advance.

 

[Guest262653]

Hello,

I think that the table is correct

If we use a simplified section (constant web and flange thickness) and assume that the plastic neutral axis is at the web inner face, you get a Wpl,z of around 144cm3: Wpl,approx = 3000x5 + 2880x45 = 144.6cm3

However, if we use the real section as indicated in the ArcelorMitall sales programme (including flange taper and the radiuses of the flange tip and of the web-flange intersection), we get the following result (I cheated - used Autocad to get the centroid of the semi-areas...):
A = 5876 mm2
A/2 = 2938 mm2
zp1 = 4.9 mm
zp2 = 39.34 mm

Wpl,z = 2938 x (4.9 + 39.34) = 129977 mm3 = 130 cm3

Hope it helps.