28
2 • Caractéristiques des sections
1. Surface :
S = S
(S1) + S
(S2) = e L + e (H − e)
= 10 × 120 + 10 × (120 − 10) = 2300 mm
2
2. Moments statiques :
H Oy = H
(S1)
Oy + H
(S1)
Oy
=
z=L
z=0
y=H
y=H −e
z dy dz +
z=L/2+e/2
z=L/2−e/2
y=H −e
y=0
z dy dz
=
z
2
2
120
0
[y]
120
110 +
z
2
2
65
55
[y]
110
0 = 138 000 mm
3
H Oz = H
(S1)
Oz + H
(S1)
Oz
=
z=L
z=0
y=H
y=H −e
y dy dz +
z=L/2+e/2
z=L/2−e/2
y=H −e
y=0
y dy dz
= [z]
120
0
y
2
2
120
110
+ [z]
65
55
y
2
2
110
0
= 198 500 mm
3
3. Centre de gravité :
y G =
H Oz
S
= 86, 3 mm
z G =
H Oy
S
= 60 mm
4. Moments d’inertie :
– Au point O :
I Oy = I
(S1)
Oy + I
(S1)
Oy
=
z=L
z=0
y=H
y=H −e
z
2 dy dz +
z=L/2+e/2
z=L/2−e/2
y=H −e
y=0
z
2 dy dz
=
z
3
3
120
0
[y]
120
110 +
z
3
3
65
55
[y]
110
0 = 9, 73 × 10
6 mm
4