Moments of Inertia, Section Moduli, and Radii of Gyration (Continued)
Radius of Gyration, k A I =
Section Modulus, Z y I =
Distance from Neutral Axis to Extreme Fiber, y
Area of Section, A
Moment of Inertia, I
Section
Triangular Sections
y
d
d
3
2
bd
bd
1 ∕
2 ∕
2 bd
3 d
. 0236 =
d
24
36
18
b
y
d
d
3
2
d
bd
bd
1
∕ 2 bd
. 0408 =
d
12
12
6
b
Polygon Sections
a
y
a b d a b 3 2 + + ^ ^ h h
a b d a ab b 36 4 3 2 2 + + + ^ ^ h h
a b d a ab b 12 2 4 2 2 2 + + + ^ ^ h h
a b d a ab b 18 4 2 2 2 2 + + + ^ ^ h h
d
d a b 2
+ ^ h
b
y
. tan d 2 3 30 0866 2 2 ° = d
cos 1 2 30 012 2 2 3 ° ° + = ^ h
2
cos 1 2 30 006 2 2 ° +
2
. cos d 48 30 1 2 30 0264 2 cos 2 ° +
d
A d
A d
h
^
°
h
^
°
d
;
E
;
E
d 2
. cos d 6 4 30
. cos d 12 4 30 4 =
=
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