This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Since the radius of gyration depends on the moment of inertia and the area of section, it follows that for a given section, the radius of gyration about two axes will be proportional to their moments of inertia about these axes.
If d equals the distance in inches from the center of each beam to the neutral axis of the two, in order to obtainI1-1 = I3.3 we must have I1-1 = I2.2 + A d2.
In the above case
I1-1 _ L2-2 = 2,087.548 - 42.538 = 23.323 d2

= 9.35 Therefore D = 2 X 9.35 = 18.70.

Angles marked • are special.
Angles with Unequal Legs.

Angles marked * are special.
Angles with Unequal Legs.

Angles marked * are special.
Angles with Unequal Legs.

Angles marked * are special.
 
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