structure on short stilts

[COEngineeer]

So I have this hut where one side of it is above the water. So we are going to use helical piers around the structure to support several beams to support the floor. My question is, how stiff are these helical piers? HOw much moment can it take to resist my lateral load from the wind? I was going to use this product:

http://www.abchance.com/applications/boardwalk.asp

Their customer service isnt very good though. I've left several messages and emails and no response yet. Can I design these piers like embeded poles? What would you do?
This is a 30'x17' gable roof canopy with no wall around it with 2x8 floor joists. One side of the hut is elevated only a few inches from the ground, and one side is above water (4' from the bottom surface).

Never, but never question engineer's judgement

 

[haynewp]

I have gotten pretty good service from them when I have called before. The piers are not really designed to take that kind of moment and stick up above the ground. You also would have the connection to address where the anchor would connect to the "hut".

They are designed by the manufacturer as they are kind of a specialty product and would need to be checked for moment by a manufacturer like the one you reference. They would also have to checked for the freestanding length above the ground to resist buckling.

 

[haynewp]

Oh yeah I would also mentioned about them being in water. Especially if it is brackish they will probably want to specially coat the piers to extend the service life.

 

[COEngineeer]

someone finally called me back. He told me to design it as 1.5" diameter solid steel (70 ksi).

Never, but never question engineer's judgement

 

[csd72]

Yes thats what they tend to use, but you wont get much lateral resistance out of that.

Another option is to encase the top few feet in concrete to give you a greater effective width.

A reference:

http://www.magnumpiering.com/shared/content/pdfs/Helix Manual Lateral Loads web.pdf

 

[COEngineeer]

Would that be too much to ask to cast conrete submerged in water for "residential" construction?

Never, but never question engineer's judgement

 

[haynewp]

I think when I dealt with the same group they handled all the design of the piers themselves and I just specified any moment or axial along with providing the soil data. Do you think they gave you the size to check just for a preliminary reference to see if they would work? Or are you actually designing the piers?

 

[COEngineeer]

I am designing the piers. In the past I usually put the axial load on it. Maybe I will put the load and moment also.

Never, but never question engineer's judgement

 

[swearingen]

Have you considered a few plumb and battered pairs? That will take out the lateral problems. Of course, the connection between the two becomes somewhat problematic.

In large marine structures we do this very often with great success. The top connection is usually either welded up or encased in concrete. The connection is designed to transfer the push/pull forces between the pile in tension and the one in compression.



If you "heard" it on the internet, it's guilty until proven innocent. - DCS

 

[COEngineeer]

This is just a little fishing hut on a private property so I dont want to make it too complicated.

Never, but never question engineer's judgement