Design of Post embedment in concrete. 1

[Lina]

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.

 

[Ron]

Please define the terms used in the equation.

 

[Lina]

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.

 

[Ginger]

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

 

[Lina]

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