concrete encased soldier piles: composite behavior 1

[nabuba]

I am designing a retaining wall using concrete lagging and encased soldier piles. The concrete encased soldier piles have channel shear studs over the depth of embedment. I want to utilize the composite action in order to reduce the design moment and hopefully bring down the weight of my H piles. Any insight would be greatly appreciated

 

[PEinc]

This sounds like a very expensive wall which will also be difficult to construct.

Precast lagging is always tough to install for anything other than a cantilevered wall which can be built in an open cut, sloped excavation. If the wall is higher and is tiedback, you will have problems with the precast and the tiebacks. These problems being coupled with encased soldier beams, you should have your hands full. You are braver than I am.

 

[InDepth]

I guess you should look at it this way, what is the cost of labor to cut/weld and install the channels? I'm guessing it would be more than the additional steel weight. Then also account for the cost in concrete for compopsite action....slurry is cheaper.

If you want to bring down weight, why not increase the size of the member and gain greater Inertia. Hopefully you don't have a restricted site.

 

[PEinc]

Without having any additional information, I can think of many potential problems with this design. Maybe steelcityflashdance could explain the sequence of construction and how the precast and tieback anchors (if any) are to be connected to the encased soldier beams. The welded channels will also increase the soldier beam drill hole size and amount of concrete encasement. These costs could be significant.

I suspect that heavier steel soldier beams will be cheap compared to the cost of the other details. Do a search for other threads about the use of precast concrete lagging. It has been discussed several times.

 

[nabuba]

Temporary sheet piling was designed in order to excavate and install the wall, due to a large surcharge loading and proximity to the roadway. There are no anchors, the tallest portion is 12’. The soldier beams will have the channels welded prior to arriving to the site and the concrete will be pumped in the augerred holes. I could easily bump the depth up, but I wanted to keep the diameter of he encased segment at 3’. I am sure the interaction between the steel and reinforced concrete encasement can be accounted for in the design, I am just not sure how????

 

[PEinc]

So, you plan to build a temporary wall in order to build the permanent wall. Again, the wrong approach. For a 12' high wall, you should be able to design relatively small soldier beams without needing composite action with structural concrete. You also should be able to build the permanent wall without needing a temporary wall also.

It sounds to me like you should put this out as a design build project for qualified retaining wall contractors. Give them the soils information, wall height, and wall length and let them complete the design and construct the wall.

 

[PEinc]

You would benefit from talking to John Wolosick from Hayward Baker in Alpharetta, GA and/or Kevin Cargill from Schnabel Foundation Company in Marietta, GA. Both are design-build retaining wall contractors.

 

[InDepth]

Steel city flash dance. It may be helpful to see a section cut of your concept. I believe the system you are looking for is a steel soldier pile with lagging and studs welded to the wx after excavation, and then a permanent wall shotcreted against it. I agree with PEInc you should easily make thiswork without composite action. Maybe your pile spacing should be looked at. Give us some more details and we canhelp.