Wall Pipe Analysis 1

[NoName1]

This is the first time I have had to detail something like this and I want to make sure I have taken everything into consideration. I have a 48 inch diameter pipe to be cast into the wall of a concrete tank with a 25 foot high wall. There is also an existing tank where this 48" diameter pipe is to be cored in the wall

How is this analyzed/modeled?

I have seen other engineers use 45 degree bars around the pipe to tie all the steel together, so could this a strut and tie model with the "truss" in the plane of the wall? Or is the pipe itself considered sufficinet to carry the bending stresses?

I don't want to pull a standard detail off the shelf without proving to myself, so I appreciate any advice.

Thanks.

 

[racookpe1978]

Is your 48" diameter pipe to be of concrete or steel?

Only seeing gravity flow (drainage, sewage, or rain overflow?) or fully-filled/pressurized flow like from a pipeline or pump?

Will it be for fluids, or to contain non-loaded stuff like electrical conduits or personnel for access through the wall into the tank?

What is height of the penetration? Any Static loads through the tank wall that must have equivalent replacement of material?

 

[NoName1]

Pipe is ductile iron and will be decant line from sequential batch reactor.

Flow will be pressurized by hydraulic head in tank.

Tank will contain wastewater.

Penetration is lower portion of wall - not sure of elevation yet.

 

[JedClampett]

For a 48 inch pipe, we just calculate the wall thickness and reinforcing without the opening and then add the amount of reinforcing cut to the four sides of the pipe as additional bars. We don't require the corner 45 degree bars. We don't analyze it. However, for our typical details 48 inch is the cutoff between using the typical and requiring the engineer to figure the opening in the analysis. Note that not everyone follows this and just uses the typical for even larger openings. Company has been in business for about 80 years and we haven't had too mnay issues doing it that way.
For the cored opening, if you can't make the section work with the hole (sometimes you can), you can cast a "collar" in the wall that reinforces it. Make sure you coat the cut bars in the wall or they will corrode.

 

[csd72]

For a 48 inch opening I would definately use diagonal bars, otherwise you will have over 10 inches to the corners of the trimmers.

As one of my coworkers used to say - it is cheap insurance.

 

[NoName1]

Thank you for the responses.

So if I have a 6" bar spacing without the opening and (just assuming O.D. is actually 48 inches for discussion)I cut 8 vertical bars. Would I add 4 bars on either side of the pipe between the verticals at 6" so the spacing would be 3"?

 

[JedClampett]

Yes.

 

[nackra]

remember the thrust collar (waterstop)

http://www.acipco.com/adip/specials/wall/thrust.cfm