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MISTERPB
Mar 9, 2007, 07:35 AM
Hi,
I'm a Mech Eng by education, but haven't used many of the skills for a long while. Can someone please run through the equations for calculating bending moment, stress, and deflection of a simply-supported beam? Maybe, for example, using a 2x10 (1.5" x 9.25" wood floor joist?? )...

As I said, I knew it once but can't recall it offhand, so a lot of explanation isn't necessary. Some brief instructions and some equations would probably bring it all back (I know trying to explain to someone who's never heard/seen any of it would be very difficult).

Thank you so much.

jimbobcooley
Mar 30, 2007, 07:45 AM
The moment at any point is the resultant of the load times the distance to the support.

Deflection is the (force * length of the beam cubed)/(48*modulus of elasticity*moment of inertia). Modulus of elasticity for yellow pine is about 13 x 10^5. Moment of Inertia for a beam 1.5x9.25 = [(b)(h^3)]/12 = 98.93in^4.

max bending stress = (max moment*half the height of the beam)/moment of inertia