Question

A beam has the following cross-section:

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where b = 6 inches, h = 9 inches, and t = 0.5 inches. Determine the moment of inertia.

I =  in4.

Answer 1

Moment of inertia about y axis 6 inch = 0.1524m 9 inch = 0.2286m 0.5 inch = 0.0127m I_Y = 1/12 times t times b^3 + 1/12 times (h - 2t) times t^3 + 1/12 times t b^3 = 2/12 times t times b^3 + 1/12 times (h - 2t) times t^3 = 2/12 times 0.0127 times 0.1524^3 + 1/12 times (0.2286 - 2 times 0.0127) times 0.0127^3 = 7.49 times 10^-6 + 3.468 times 10^-8 = 7.524 times 10^-6 m^4 = 18in^4