Space Between Concrete Piles

[hth]

Technically when doing underpinning under grade beams, how far is maximum between piles supporting grade beams? Is it the same for piles supporting footing? I, not a PE, heard the maximum is 6 ft, others say 8 ft.

 

[hth]

I am asking for steel piles, not concrete piles. Sorry folks.

 

[Ron]

We generally space them at 4 feet for footings. If you know anything about the grade beams, you might be able to stretch that depending on how much load the grade beam is designed to take.

 

[SperlingPE]

Knowing the reinforcing in the grade beam, the load on the grade beam, and the soil conditions is the best way to determine the spacing for piles. Without knowing these items, stay conservative and use an engineer's judgement.

 

[hth]

I finally got it from the print. It is 7'4" for my house. I know I asked a question without specific details. Sorry.
Another question. After pushing the piles to get a desired load, the installer bolted the steel piles into the brackets. Is it strong enough to hold the load or piles must be welded to the brackets? They are 16"x12" grade beams. My house is one story. Interior load = 1173. Exterior load = 941. They use gal. wire to tie up the re-bar steel at slab and grade beams. I was thinking they would be welding.

 

[PEinc]

In my opinion, you have not provided enough information for any type of answer. For example, where are the piles to be driven? Next to or under the grade beam? What type of brackets are to be used? Does the grade beam bear on top of the brackets or are the brackets attached to the side of the grade beam? What is the load on the bracket and the pile pile and what is the size of the bearing plate under the concrete?

The pile spacing is a function of the bracket strength, the available pile capacity, and the load capacity of the grade beam. All need to be checked. The smallest spacing should be used.

Was the design prepared by a professional engineer? If not, get one who is familiar, no, make that "very experienced" with pile design and underpinning design. Familiar isn't good enough.

 

[hth]

Sorry I am not in the field so I don't know what you need. Anyway it looks like below. This is crossing view of the beam. The o's = the beam, the x's = the plate and the l's = the tube. This was designed by a licensed PE. However I just have questions because the look-like poor workmanship performed plus the contractor charged me way, way less than a well known company specializing in underpinning that you can easily google out. He have an OK record, no bad things logged.


xlll x ooooo
xxxxxxxx ooooo
xlll x ooooo
xlll x ooooo
lll x ooooo
lll xxxxxxx
lll xxxxxxx
lll
lll
lll
lll
lll
lll
lll
lll

 

[DRC1]

If you are concerned you probably are seeing things that don't look right. I'm sure you spent a lot of money on this repair already, but if you have concerns you should spend a little more and get a good geotechnical engineer to look at it right away. Waiting never improves the situation.On a finla note rebar is usually tied with wire prior to pouring. Welding can damage normal rebar. Special rebar is made for welding.

 

[PEinc]

If the engineer who designed the repair is independent from the contractor, you may want to call him and have him do an inspection of the completed work. Or, as DRC1 said, call another engineer.

 

[hth]

thank you you guys.