Circular hollow section

Formulas

Cross-sectional area

$$A = \frac{\pi}{4}\ \biggl[ d^2 - (d - 2\ t)^2 \biggr]$$

Second moment of area

$$I = \frac{\pi}{64}\ \biggl[ d^4 - (d - 2\ t)^4 \biggr]$$

Elastic section modulus

$$W_{\mathrm{el}} = \frac{\pi}{32\ d}\ \biggl[ d^4 - (d - 2\ t)^4 \biggr]$$

Plastic section modulus

$$W_{\mathrm{pl}} = \frac{1}{6}\ \biggl[ d^3 - (d - 2\ t)^3 \biggr]$$

Shear area

$$A_v = \frac{2\ A}{\pi}$$

Notations

• $d$diameter, in mm
• $t$thickness, in mm