Circular tie details for drilled piers
Circular tie details for drilled piers
(OP)
I have two concerns about the circular ties (#6) for my drilled piers (for river embankment stabilization, under mostly large bending and shear, minimum axial, 36"dia, 24#11 with #6 ties @ 3"-4" spa)
1. The lap length - is 48 db sufficient (36" as lap length)?
2. the lap details - should the lap steel be overlaping with the circular tie or turning into the interior of the cross section(seems to be preferred by FHWA)? If the lap is 48db (36") there is barely enough room for the lap. What about the constructibility?
Thanks for the help!
1. The lap length - is 48 db sufficient (36" as lap length)?
2. the lap details - should the lap steel be overlaping with the circular tie or turning into the interior of the cross section(seems to be preferred by FHWA)? If the lap is 48db (36") there is barely enough room for the lap. What about the constructibility?
Thanks for the help!






RE: Circular tie details for drilled piers
Ols CA SE
RE: Circular tie details for drilled piers
Also, if the member is taking mostly bending and shear, it's classified as a tension controlled member and the requirements for column ties don't apply. However, the requirements for shear stirrups take over.
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
These shafts are one of the many sections of shafts along the river emankment. The clients wanted use same diameter shafts (36") and similar details....same strength of concrete...therefore to cut their cost. They claimed that #6 ties have been used in another section. Although #6 circular ties may be out of the ordinary but will it be a solution? I am mostly interested in the details of it......
Thanks!
khkw
RE: Circular tie details for drilled piers
Getting the concrete down the shaft might be an issue (as Jed suggested above). One thought would be to fill the pier up to a point and then drop in an internal rectangular cage, tie it off to the cirular cage and then continue with the concrete placement.
But tying it all together at the start is preferred.
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
What is the standard hook length for this 135 degree bend between two legs of the tie? My vertical bar spacing is 3.5"......
RE: Circular tie details for drilled piers
Otherwise, I would defer to CRSI and use the 48 bar diameter lap length. I suspect some of the (24)-#11 get cut off about 15 feet down along with most of your shear reinforcement?
RE: Circular tie details for drilled piers
It takes about 9" or 10" for a standard hook of a #6 bar. Again, check with a reinforcing supplier. With a 3.5" bar spacing, you may want to make the hooks overlap 4 spaces or so.
RE: Circular tie details for drilled piers
Hokie66,
Out of the 9" to 10" hook length half is bent and half is straight in the section. It may not be as bad as it sounds. I will check details of ties with the reinforcing supply.
Teguci,
As far as the location of the max moment and shear -according to the geotech analysis, since the shale layer is down 30' in depth and the layers above is not good stuff, the max shear happens at the sliding surface (30' in depth). And max moment occurs at the same location. Geotech engr used slope stability analysis and L-Pile to compute the loading (M and V) in the shaft - lots of assumptions and uncertainties incolved. I don't plan on cutting the vertical bars. As for the ties I will beefup the middle section with 3" spacing and cut down to 6" tie spacing at top and bottom 10' sections (total shaft length 45'. This might be an overkill but it covers the uncertainties.
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
Dik
RE: Circular tie details for drilled piers
RE: Circular tie details for drilled piers
Thanks so much for all the great input!