Radius of Gyration of a Section
Radius of Gyration of a Section
The radius of gyration packages a section’s stiffness and area into one length used to assess buckling.
The radius of gyration is r = √(I/A). where I is the second moment of area and A the cross-section area.
Inputs
I := 8.0e6 mm^4=8e-06 m^4
A := 3000 mm^2=3e-03 m^2
Take the root of the inertia-to-area ratio.
r := sqrt(I/A)=51.64 mm
Results
A larger radius of gyration means a section resists buckling better for the same area — why hollow and wide-flange shapes are efficient columns.
Assumptions & limitations
- Gross section properties.
- About the relevant axis.
- Used in the slenderness ratio KL/r.