Pole Embedment 4

[RWF7437]

"The following equation is used for minimum pole embedment:

embedment=(1.18*P/b*S1)*(1+(1+(1.88*b*S1*H)/P)^.5

S1= soil compressive strength, P=Lateral Load, H=pole height, b=pole bearing width

(Some)program(s) use a minimum embedment value of 4 ft.

The above will allow up to 1/2" movement at the surface of the soil."

Can anyone tell me the origin of this equation ?

Am I correct in believing it is essentially empirical; based on tests ?

Can anyone provide a source for a description of those tests and a discussion of the theory, if any, behind this equation and its limitations ?

 

[smb4050]

I've got documents published by the AWPI (American Wood Preservers Institute) and authored by Donald Patterson titled How to Design Pole-type Buildings unknown publication date and Pole Building Design 6th edition (1969) which references the Outdoor Advertising Association of America Engineering Design Manual - 4th edition (1955) and Prof. P.C. Rutledge from Purdue and Northwestern Universities. At one time I looked on the web for a copy of this manual but couldn’t find it. My 2 manuals have a nomograph for a graphical solution. From memory I think they have the same formula except for different coefficients. I hope this helps.

 

[RWF7437]

Thank you. That helps some but coefficients and their origin remains murky. More recent standards, e.g. Building codes and ASCE 7, appear to be based on different test data. It is rhar rest data I seek so I know how far to trust rhis ibscure formula.

Thanks again, though.

 

[BigH]

might find the following of interest - haven't read it in detail, though.

http://www.cti.uconn.edu/chwrp/pdfs/jhr76-102_74-1.pdf

 

[smb4050]

My recollection is I've worked through each equation and found out that the formula you referenced is just a simplified version of what is in the references I listed perhaps involving unit conversions. I've read about the 1/2" deflection limit and Monday will try to find it.

 

[SlideRuleEra]

smb4050 - I have "Pole Building Design", by Patterson, on this page of my website:

http://www.slideruleera.net/miscellaneous.html

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[RWF7437]

Thanks to all who posted. The references provided by BigH and SlideruleEra were exactly what I needed.