pipe cantilever

[mjh250473]

This should be simple one - but have no formula book.

I have a pipe sticking out of the ground that has been pushed down with a excavator bucket to align with the adjoining pipe.

i want to do a simple calc based on a cantilever beam (but with a pipe fixed in) to find the max deflection allowallable for given SMYS.

any good web sites..? or formulas known? Thanks

 

[carthago]

Yield for say A-333 Gr. 6 is about 240 N/mm2
You have to avoid yielding.
Avoid Bucling
Avoid denting ( local deformation)


A fixed pipe at one end clamped ,pipe length = L, with a bormal force F at the other end, will give:

Max. bending moment = F*L

Max. bending stress = F*L / (modulus of resistance)

This Max Bending stress should be about < (0.67 * Yieled = 161 N/mm2)

Modulus of resistance = ( 3.14/ 32 )*[ (Do ^4)- (Di^4) ]: Do
in [mm3]

Do = pipe outside diameter in [mm]
Tnom = pipe nominal thickness in [mm]
Di = Pipe inside diameter [mm]
Di = Do - 2*(0.875 * Tnom)



Deflection = F * (L ^3) / ( 3*E* I)

E= Young modulus 210 000 N/mm2
I = Moment of inertia = ( 3.14/ 64 )*[ (Do ^4)- (Di^4) ]
in [mm4]

You coan find all the above and ..more on the net or in Roark book, etc

 

[JStephen]

I don't know that you'd need to avoid yielding- steel products can be cold formed to varying extents- typical in plate rolling, angle rolling, for example.

 

[Ron]

One thing you have to consider is where you achieve fixity in the soil....top of the ground is not the start of your cantilever.

 

[azcats]

"Pole Building Design" by Patterson gives some information on Ron's point. It's available at SlideRuleEra's webpage at

http://www.slideruleera.net

. The moment in the pipe can continue to increase well below the top of soil.

Also, "Tentative Criteria for Structural Applications of Steel Tubing and Pipe" by D.R. Sherman, Ph.D. offers some good information on allowable stresses in tubing and pipe.