Friday, January 27, 2012

CM and CF and Fb ... all tangled up!

 ... note that C_F and C_M are all tangled up.  I mean that to get C_M for flexure (for Dimension Lumber) ... you also need to know C_F (and F_b).  Look at the table on the left side of page 30 in the NDS SUPP about half way down.  The table gives a value for C_M on F_b, but the problem is ... there is a little " * " thing.  As we look below it indicates that C_M actually depends on what C_F times F_b is.  Wild. 

Attached is a page from my solution to Problem 1, Part a) of our Assignment 6 ... that shows how I deal with it (and the other Adjustment factors for bending for that part of the problem).


Note:  jus cuz I show the 2 x 8 in the calcs above - it does NOT mean 2 x 8 is the final answer ... I'm just checking the 2 x 8 to see if it works!
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