Precast Concrete Piles 2

[LPPE]

Anyone have any details on precast concrete pile splices, and pile cut-offs? Interested in both plain reinforced and prestressed piles.

How would you cut off the pile at the pile cut-off elevation and dowel it to the pile cap or slab if it's a prestressed pile?

 

[UcfSE]

FDOT Standards:

http://www.dot.state.fl.us/structures/StructuresManual/CurrentRelease/FDOTBridgeManual.htm

Click on Volume 4, go down to sheet series 600, specifically 601: "Square Prestressed Concrete Pile Splices".

Obviously you can't just take the drawings and use them but they may give you ideas. You'll have to do all the engineering calculations and drawing production to see if they actually fit your application.

 

[SlideRuleEra]

Here is one specification for piling cut off, see paragraph 7.4

http://www.gov.mb.ca/tgs/contracts/specmanual/1016.pdf

In my bridge contractor days a common way was to cut (chip) the concrete with a pneumatic pavement breaker and snip the stands (or rebar in precast concrete) with an acetylene torch. When cut, the stands would snap with a "twang" sound but not recoil since both side of the cut (the pile itself and the pile cutoff) had the remaining length of the stands completely encased in concrete. This approach was both slow & labor intensive, concrete saws are probably better suited and more available now.

If dowels were needed, the top of the pile was drilled, axially (after cut off), and rebar grouted in place.

http://www.SlideRuleEra.net

 

[LPPE]

UcfSE and SlideRuleEra - Excellent links and information you have provided. Thank you, it is much appreciated!

 

[Lutfi]

Watch for details of splice when tension load is present in concrete piles!

Regards,
Lutfi

 

[DRC1]

Prestressed precast piles are pretty much standarized. A local precaster should be able to give you details of pile crossections. Splices are avaiable, but are usually installed at the precaster so they match. They can get very expensive. There is a sweedish system that is very good. Check trucking lenths with the precaster. Typically maximum truckable length (with permit) is 100 to 120 feet. Cut off can be accompliseshed with cut-off saws or special pile head cutters designed for precast piles.

 

[unclesyd]

Somewhat dated:
There was a show last night on the History Channel on the construction of the Lake Pontchartrain Bridge that had pretty good coverage on the manufacture and installation of the concrete piles.
The piles used were spun cast sections (? 4 5/8" tk x 30'lg) with 12 or more holes longitudinal holes for tensioning, the sections were stacked and post tensioned and grouted. At the site the piles were placed with a steam driven hammer and trimmed to height with a concrete saw. I think they call the cap a bar cap, which had been precast onshore and from the picture the cap was anchored to the pilings with a concrete plug. There were circular reinforcing cages attached to the bar. The precast bridge sections were set on the bar. I didn't see but one pin on at each corner. This maybe the reason it came apart like our I-10 bridge.

This took place in the 50's but a very similar system was recently used on 3 fairly long bridges across our bay. The only difference was that more of the caps were cast in place.

 

[unclesyd]

Here is an interesting website that my help you. I saw the name on a piece of equipment being used on a bridge repair.

http://www.vulcanhammer.net/info/pilecutter.php

 

[crossframe]

Another consideration for pile cut-offs is the mild reinforcing steel extending from the pile top (used to help tie the pile to the footing). From what I remember, these bars are often only about 12 ft long, so if the pile cut-off is excessive you won't have much bar left in the pile.

Caltrans (Californis DOT) also shows reinforcing details in their Standard Plans manual.