top down construction

[jloo73]

Anyone know of any good references or rather any reference on top down construction?

I've found a few articles and have some different ideas about how to go about it, but want to know if there were any other references.

Thanks

 

[jike]

I don't know if you mean "up-down" construction. This is a technique in hi-rises where you are building upward with framing above grade as excavation and various basement levels are also being constructed. This saves time and money.

I know of no references other than decriptions for particular buildings.

 

[Zambo]

jike,

he means "top down construction" this is where you construct basements from ground level down. First you construct diaphragm walls and bored piles, then you excavate. When you reach the level of the first basement level floor you cast the slab, this struts the diaphragm walls. Then you lift an excavator through a hole in the cast floor slab to excavate for the next level down. Work continues until you reach the lowest level.

There are advantages, in particular that no struts, or at least reduced strutting is required. Disadvantages include the need to provide ventilation for the diesel engined excavators and of course spoil removal is slow by crane and skip.

 

[jike]

We must be talking about the same thing but I have heard it referred to as "up-down" construction.

 

[jloo73]

You are talking about the same thing, just different lingo.

In keeping with the same discussion, has anyone constructed a basement using steel sheet piles and left them exposed as the basement walls. What are the fireproofing implications if any thay you may have run across. From a structural standpoint I don't see a problem if the walls are designed, I can only think of fire rating being a problem.

I'm throwing the idea out since sheeting will be cheaper than a slurry wall.

I know that local jurisidictions will have a say in all this, but wanted to know if anyone has successfully used this option.

 

[PSlem]

I got a brochure at ASCE convention in Chicago where a sheet piling manufacturer was showing this for European parking decks. Painted and looking good. I don't recall name, though.

 

[Zambo]

The sheet pile solution on first look seems a good idea. Exposed sheet piles are often used for bridge abutments and can look as good as CIP concrete. However I would expect that if you were going to construct on top of the basement walls you would have considerably higher load bearing capacity for diaphragm walls than sheet piles. You also have to consider the structural connection between the sheetpile walls and the proposed basement floor slabs. I would expect that when you take the above factors into account diaphragm walls will be less expensive.

 

[Azz90]

Sheet piles have been used throughout Europe for over 30 years as permanent basement walls. It is becoming more common in the US. What most people don't realize is that the sheet piles walls typically have plenty of excess capacity to support vertical loads. A distrbuted wall load of 20k/ft would not be a problem. The connections to intermediate slabs can be made numerous ways, as you have the entire face of the wall to connect.