Helical Anchors

[DHKpeWI]

We are thinking of using helical anchors to hold down a temporary structure being installed on an existing parking structure. The uplift loads are 1,500 to 2,000 pounds. Chance anchors will work but the capacities are much large than I need. What anchors would you use in this applicacation?

 

[MikeDB]

Chance makes a wide variety of screw anchors for different soils and holding strengths. Your loads are very light, so I would go with what can be installed cheapest with the equipment and tools you have available. For those loads you could bury a board with a rope tie.

 

[TLHS]

There are small helix anchors available, but they tend not to be engineered products as much, so you'd likely need to run your own numbers to prove to yourself that they work. I'm sure you can find some though that satisfy you. Even a four inch helix should do what you're looking for. That sort of thing is used for tarp tie downs and tents and things and they're pretty cheap (as in a couple dozen bucks maybe)

For example, this type of place.

http://www.americanea.com/products.php?cat=52

Or, yeah, just bury a pipe or a board or something

 

[ztengguy]

What do you mean by helical anchor? What the other posts talk about go into soil, not concrete. If you need a tie down for concrete, just use a expansion anchor. you said existing parking structure

Perhaps a picture of what your doing?

 

[MiketheEngineer]

There are a number of helical mfgs out there. Look around. With that load - maybe #4 re-bar drive into the ground will work. Not sure of the values - but you could test.

 

[TLHS]

ztengguy,

Helical anchors are basically soil augers used as tension anchors or, in the case of larger ones, piles.

Traditional helical anchors are either rods or square bar with a helix on the end that are driven by hand or mechanically into the ground. They're great for things like guyed structures where you're only going to see tension loads. They're quick to install and relatively cheap.

In the last decade or so helical *piles* have gotten popular in some places. They're effectively pipe piles with a helix or two welded to the bottom. They're great in compression and tension and go in really really fast. They're installed using a screw head that's normally installed on an excavator or some sort of truck mounted crane. You can also install them in fairly tight spaces and where things like driven piles wouldn't work because of the impact.

 

[msquared48]

Helical anchors are used a lot as tiedown anchors for Mobile Homes.

If you want more choices, google Mobile Home Tiedown Anchors.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[ztengguy]

He said it was to be installed on a existing parking structure, I read that as a parking garage type structure. If its a parking lot, I get the helical anchors.

If I owned a parking lot, I wouldnt want those drilled thru it, but perhaps that doenst matter.

 

[PEinc]

If the anchors are to be installed into soil, look at Manta Ray or Sting Ray anchors in the Williams Form Engineering catalog or on their web site. They are lower capacity than most helicals.

http://www.PeirceEngineering.com

 

[MiketheEngineer]

If it is concrete or asphalt - you are going to "mess" up a bunch of either. Concrete anchor bolts work well in concrete - something like 1/2'x4' for your app. However, not so good in asphalt....

 

[Brad805]

Sounds like you need some $50 used lock blocks if you have equipment on site to move them easily.

 

[MiketheEngineer]

We often use "highway" barrier blocks - sometimes known as Jersey block, K-rail, Eco-blocks etc. You can get them in various sizes/weights and can be rented.