I remember an old post about garages where someone mentioned installing tie down bars in the floor before the slab was poured. Did a search, but couldn't find it. Something about putting rebar in pvc and having it level with the top of the slab. Anybody remember the thread or have a good idea on how to install them? I remember they said it was good for straightening frames or to hook a come-along to to pull non-running vehicles into the garage. Getting ready to start my garage build and it sounded like a good idea.

 

I also put c channel open side down with anchors welded on to it about 24 to 36 inchs from the wall around the shop. This way when I mounted my bench grinders, drill presses, bench, pull rings. I just welded them to the floor. Want to move them grind them off. If you want pics let me know

 

chain anchor pots are what I think you are refering to. http://www.autotoolmart.com/cgi-bin/..._sresults.html

 

I am just going to epoxy some 3/4" coupling nuts into 1.25" drilled holes in my floor. Then I can bolt down some plates to fasten a chain to. If I pull to the side it should be OK. I figure on using some 1" long 3/4-10 All-thread "plugs" with a big screwdriver slot covered with anti-seize when not in use.

Coupling nut:
http://www.acehardware.com/sm-coupli...1.1255041.html
http://www.fastenersuperstore.com/
http://www.pointe-products.com/


Those chain pots are better if you are going to use them a lot tho. I can imagine the installation is $$$ tho.

 

Threaded rod couplings are only about 2 inches long. This is not much embedment and it is questionable how much shear strength (what it means when you say "pull to the side") you are going to get. The smooth sides of the rod couplings present a question as well.

According to Simpson's design table, available here:
http://www.simpsonanchors.com/catalo...concshear.html

A 1 inch diameter rod (we'll use this as an approximation of the rod couplings) has a minimum embedment of 4 1/2 inches to obtain an allowable design shear strength of
7630 pounds. It has a minimum distance of 13 inches to any edge of the concrete, and may be spaced no closer than 6 3/4 inches from any other such rod. A 3/4 inch grade 2 bolt has a shear strength of 4360 pounds. A grade 8 bolt would be around 9000 pounds.

Your slab is probably not thick enough for 4 3/4 embedment. You might be able to obtain 3 1/2 inches of embedment by careful drilling. Use two rod couplings stacked end to end. Cut one of them short to obtain a total length of 3 1/2 inches. Thread them onto a piece of all thread, then tack weld them together so they act as one rod coupling. Thread the all-thread almost all the way to the bottom of the stack, then seal off the blind end with a plug of silicone seal. This is to prevent the epoxy from getting into the threads when you install the rod couplings.

If you later use bolts long enough to thread all the way down (3 1/2 inches), you might then have an anchor good for 5000 pounds or so. This is outside the parameters of Simpson's tables, and is really only a guess.

As with many building related products, especially those involving unpredictable materials like concrete and epoxy, there is a large safety factor built into the "design strength". Typically, the safety factor is about 4, so you should not be surprised if the anchors will hold closer to 15000 pounds. At this point, the 3/4 inch bolt will break, since steel has a much lower safety factor.

But don't use the safety factor to try to get by with just 2 inches of embedment. The concrete will just spall away from the rod couplings at a fairly low total stress.

 

Good idea! Thanks for the links.

Most of the concrete I have is 6-7" thick so two coupling nuts welded together is no problem. They are 2-1/4" long so they make 4-1/2" together. I could even thread them over a 3" long all-thread for a little extra strength and leave it in after welding. All-thread is not very strong tho, I have never seen what "grade" it is supposed to be. The 1.5" of thread left in the top nut would be adequate for most bolts. A couple tons of shear strength would probably be adequate for my garage work. A grinder or hacksaw could "serrate" the edges of the nuts if necessary. I used to be able to get 3/4" coupling nuts that were about 4" long but I have not seen them for years. I do have one section of 4" thick concrete I want to put one in so I will have to figure out how to get an adequate coating of epoxy on that assy.

 

I have 4 anchor pockets installed in my shop floor in a rectangular pattern. Each one is a 1/2" x 12" x 12" steel plate with a 6" long piece of 4" steel pipe welded to the middle of one side. A 12" or so long length of 3/8" chain is is run down through the pipe, with a slot cut in the plate the bottom link runs through. The link is pinned under the plate and welded.

The whole assembly was set into the floor when the floor was poured. A 6" square of 1/2" plywood was attached to the top of the pipe for the pour to keep concrete out and allow the top of the pipe to set 1/2" below floor level. When the concrete was hardened enough, we broke the ply wood out, and can drop a 1/2" x 6" x 6" steel cover plate over each one, and have it sit flush with the floor. By the way, my whole floor is not 6-1/2" deep, we just went a little deeper at the anchors. Average thickness is about 5".

 

Anyone ever think of embedding a guard rail anchor in the floor? They are available in different patterns, with varying number of posts. Also you can get them for different depths, and usually they have either 3/4" ferrules or 5/8" ferrules.