What Are This Tube's Section Properties?
The HSS section properties calculator gives area, moment of inertia, section modulus, plastic modulus, radius of gyration and torsional constant for any size and wall.
Calculator
How the Properties Are Figured.
The section is measured the way AISC tabulates hollow structural sections: outside corner radius twice the wall, inside radius one wall. For a 4 x 4 x 1/4 at its .233 in design wall, the calculator gives the same area, I, S and Z as the AISC Steel Construction Manual.
x is the axis parallel to the short side, so Ix is the strong axis of a rectangle standing on its narrow side. Plastic modulus Z is figured from the area on each side of the axis. The torsional constant J uses the thin-wall formula on the wall's centerline.
AISC 360 has engineers design A500 tube with a wall of 0.93 times nominal. Tick the box to see the properties at that wall; weights are always shown at the nominal wall.
Round: I = π (OD⁴ - ID⁴) / 64, S = 2I / OD, r = √(I / A)
Torsion, square and rectangle: J = 4 Ap² t / p
Questions
What is the moment of inertia of 2 x 2 x 1/8 tube?
With a nominal .125 in wall, 2 x 2 square tube has a moment of inertia of about 0.51 in⁴ and a section modulus of about 0.51 in³ about either axis. Use the calculator for the exact figures and the design-wall values.
Should I use the nominal or the design wall?
For structural design to AISC 360, use the design wall for A500 tube (0.93 x nominal). For weight, deflection checks against a supplier table, or A513 mechanical tube, the nominal wall is the usual choice.
Are these values certified?
No. They are calculated from nominal dimensions for planning. Your engineer of record should check any structural design.
Does A513 tube have the same properties?
Close to it. A513 corners are often sharper, which adds a little area and stiffness. For design, use the properties for the specification you buy.