design of post embedment in concrete

huangyhg

design of post embedment in concrete.
i have seen the following formula for designing post embedment in concrete:
a = (2m^2 + 3lm)/3m + 6l
do you know where i can find this formula?
other engineers have used it to calculate embedment of guardrail's posts in concrete.
please define the terms used in the equation.
ron.
m = embedment of guardrail post in cobcrete slab usualy equal to 4"
l = the height of post over finish floor (or slab)
     this value should be 42" as per all local codes.
a= distance of first triangular stress below finish floor
after a is obtained other engineers have used it to calculate the force below concrete using this formula
p2= (a^2 x p)/[mx(2a-m)]
where p is the lateral force on top of the post and as per local codes this force should be 200lb
thanks for your help.
don't know about your equation but there is a good example in the steel designer's manual 4th edition published by the steel construction institute.  look under pocketed crane bases.
regards
andy machon


more details on these formulas:
a=     2 m2 + 3l.m /3m   + 6l
p2=     a2 x p / [m(2a-m)]
m is the embedment length of the post in the concrete slab
l is the height of the guardrail post
p is the lateral load applied on the top of the post described abve
p2 is the resisting force to p below concrete slab