ibc eq 18-1

huangyhg

ibc eq 18-1
does anyone know if the equation for "a" in eq 18-1 of ibc 2006 is correct.  it almost seems like there should be parentheses around the s1b in the denominator of "a".  the way it is written the required depth of footing increases with a larger footing, and i would have guessed that it would decrease.  i can't think of any logical reason that it would want to increase for an increased diameter footing.
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you are correct. it is not clearly written in the code book. b should be in the denominator for the this equation and also the restrained condition equations 18-2 and 18-3.