Help on Area Moment of Inertia

ckjohn

Hello, I am trying to calculate the second moment of inertia for a hollow tube with a reinforcement bar that goes through the tube. The cross section is basically a thin-walled circle (0.1" thickness) with a horizontal bar (about 0.1" thick for now) that spans the diameter of the circle. How would I go about calculating this?

Thanks in advanced for your help!
Jay

Mech_Engineer

Since their centroids are coincident it will just be the sum of the two individually. As with an I-beam, you can split the section into "constituent components" and add their individual section moduli together. For components with offset centroids, an area-weighted summing technique is used.

http://en.wikipedia.org/wiki/Second_..._cross_section