residential pier & pile design 1

[TomTX]

What is a good, basic resource for designing belled-pier and pile systems to support the slab foundations of residential and small commercial structures? Have reviewed IBC & IRC but always appreciate examples. Any on-line tutorials? Anything otherwise easy to access when not near an engineering library? Thank you.

 

[PSlem]

Usually the pile is good for more capacity than needed. The spacing requirement is more for the grade beam span. We typically run piles from 5' for 3 story to 7' for 1 story and the grade beam is 16" x 20" deep as you want 12" of depth and an additional 8" on the exterior gets the siding out of termite's reach, in other words conventional footing sized. You have to use both top and bottom steel. If you stretch them out to where beam shear is a factor, then the cost goes up with stirrups. Interior grade beams are 4"-8" shallower. You can pull all you need out of the ACI 318.

The optimist sees the glass as half full. The pessimist sees the glass as half empty. The engineer see the glass as too big.

 

[TomTX]

Thank you, PSlem. I should have mentioned that expansive soils are definitely a factor for us here on the gulf coast. How might the pier diameter, pier depth, bell diameter, etc. depend upon soil boring data? I know generally that the pier should go to a non-expansive depth. However, there must be specific guidelines/requirements. Thank you in advance.

 

[PSlem]

Here you are probably better off asking a local drilling contractor. I've only worked Texas on skyscraper cofferdams. Good book sources for this type of question are the earlier books by Dr. Brown, simple and directly related to residential. We do everything by the Standard Bearing Equation formula. But you will need some feel for how cohesion relates to blow count or some better soil info.

The optimist sees the glass as half full. The pessimist sees the glass as half empty. The engineer see the glass as too big.

 

[BigH]

Sorry PSalem - many engineers I've known many times can't even see the glass! - they've already toppled.

 

[TomTX]

Thank you again, PSlem. I know this may sound bad, but who is Dr. Brown and what might be a book title or two? You can tell that I'm in a different field and pretty ignorant in geotechnical area.

 

[PSlem]

I will ck my books Mon as a quick amazon search came up empty. He was a piling and underpinning contractor in Texas. A good site is

http://www.texasce.org/frm.cfm?x=Guidelines

These cost me $35 a couple years ago and are free now.

The optimist sees the glass as half full. The pessimist sees the glass as half empty. The engineer see the glass as too big.

 

[TomTX]

PSlem, thank you for offering to check your books and for the web site. The references at texasce.org appear to be good overviews but not to offer design specifics. I appreciate your help so far.

 

[PSlem]

I didn't make it to the office yesterday. Stayed at the job sites. Look for Design and Repair of Residential and Light Commercial Foundations by Robert Wade Brown McGraw-Hill 1990

The optimist sees the glass as half full. The pessimist sees the glass as half empty. The engineer see the glass as too big.