Securing 3/4" Threaded rod in Cement

I'm installing a 250 gallon oil tank for the shop furnace. For
reasons I'm not gonna get into here I'm mounting it on two right
angle frames secured to the foundation wall.
The frames are 3" x 3/16" angle- approximately 16" on the verticals,
with the horizontals extending about 37" out from the wall. Theres
diagonals running from the bottom of the uprights to the outboard ends
of the horizontals.The tank's weight will be centered about 24" out
from the wall.
| Tank
Wall [ ] [ ]
[ ]|______[__]_________________[__]_
[-----------]|______________________________| Horizontals
[ Rod ]| | __--
[ ]| | __--
[ ]| | __---
[ ]| | Verticals __---
[ ]| | __--- Diagonals
[ ]| | __---
[ ]|_|__---
[ ]
[ ]

On one of the frames I can run a bolt through the wall but for the
other I had to drill a 3/4" blind hole 8" deep into the foundation.
I just ain't good enough to figure the tension/shear ratios on the rod
( :( ) but I figure 1000 lbs worst case tension on the rod as the tank
fully loaded will weigh
about 2000 lbs.
Q.- will an 50-50 epoxy/sand mix gooped into the hole & onto the
threaded rod hold it in? FWIW the epoxy is West Systems 300 series,
really designed for fiberglassing but its what I got handy. The sand
is 40 mesh silica from my sandblasting stock.
I'm figuring it will hold O.K. but I'd like some sort of learn-ed
reassurance, 250 gallons of oil spilled in the back yard is trouble I
*Don't* need. :/
Reply to
Howard Eisenhauer
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I would really dig deep into the Boston Underground epoxy failure history before committing yourself to your mix... which sounds risky to me... I think microbaloons or fiber might be better than sand to mix with the glue.
Reply to
Wayne Lundberg
Rather than experimenting with epoxy, is there any reason not to resort to a proven fastener like Hilti Quickbolt
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or its competition? I have been using them for decades without a hint of a failure.
Reply to
Vaughn Simon
Actually, it's 3,000 pounds on the bolts, or 1,500 pounds per bolt, minimum, since the horizontal arm is longer than the vertical. And that's only if the top bolt is at the very top of the arm, which it won't be. So it will be more.
Read up on the accident in Boston's "Big Dig" tunnel for an example of what creep or flow in an epoxy - and using the wrong epoxy in the first place - can do.
Sorry I can't give you the reassurance you seek. Maybe someone else can.
John Martin
Reply to
John Martin
I would go to a real construction supply house and ask for proper cement fasteners (rated for your pull rating) and rent a tool to properly get them seated. I figure that for $100, you will be all set, based on nothing but a gut feeling.
Reply to
Maybe this might be a good time to get into the reasons you don't want to mount it on something that has straight down compression strength.
It's a flammable liquid. You better be right, and I like things three times stronger than they need to be. Particularly when dealing with flammable fluids.
Let us know where you live so we can keep an eye on the newspapers.
Reply to
Expect the rod tension to be MORE than the weight of the tank Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/
Reply to
Nick Hull
I'd say your plan looks like nothing but potential trouble.
First, you better check the building codes in your area. What you are trying to do may violate those codes and require you to completely rework your entire situation......after you have drilled holes in your foundation and had the certain to appear cracks show up. The building inspector may require you to rip the entire thing out just to satisfy the code and issue you a citation which could lead to all sorts of legal nonsense.......particularly if you ever put your place up for sale.
Probably the code says to pour a concrete pad of some given thickness and set the tank on it. If that's what the code says, that is what I'd do.
Second, do you really want to screw with the foundation of the building? I can see stress fractures developing and spidering out from the bolt holes, along with a nice concrete plug pulled out from the foundation, as the torque on the system varies with the oil load in the tank: particularly if you anchor the bolts to the concrete with some type of epoxy. This will not allow the bolts any "wiggle room" as the oil load changes and will likely crack out a big plug of your concrete foundation.
A possible solution to this is to use two 3/8's inch steel on the inside of the foundation and one on the outside of the foundation. Use one inch bolts with only threading where the nuts will be threads in contact with the shear forces created by the downward pull of the plate and load. Silicon caulk around the bolts to prevent water seepage through the bolt holes.
The plates with spread the load over a wide area on the inside and outside of the foundation....if you use enough bolts and tighten them properly.
Then weld the required brackets to handle the oil tank on the outside foundation plate.
Rethink your plan. Check the code. Pouring a pad is the best way to go IMO. Dave
Reply to
Your guess at about 1000 # may be right for shear, but I think the tension number will be higher on a 24" lever. Your choice of 3/4 all thread overkills your numbers anyway. Those fellas in Boston thought they could outguess their own epoxy formula too. It is too bad that they drug Powers into the deal as their literature defines applications, and the contractor did not follow the requirements or use the correct product.
Epoxy executed properly is rated to be stronger than other forms of concrete anchors. there are epoxy systems made by many major manufacturers made to work with conventional all-thread. Hilti Powers Simpson Red Head They all require a particular bolt size in a particular hole size with sufficient cleaning of the hole. I use quite a bit of the Red Head C6 product. Here is their tension and shear table for their C6 product, showing 28, 779 # in tension on a 3/4 threaded rod @ 6 3/4 embedment in 2000 # concrete:
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For those who were suggesting mechanical anchors: Their wedge anchor : 3/4, embed 6, 2000 conc, = 10, 980
Reply to
Howard Eisenhauer wrote in news:
Your wall is designed for a vertical load, not a cantilevered load. You don't mention of what material your wall is constructed. If it is solid, poured, steel reinforced concrete, you may be ok (maybe). If it is block construction, you are asking for trouble. You could modify your design to use two vertical legs on the outside, supported on concrete pads, and place only vertical loading on the wall. The safest thing is to self- support the tank on it's own legs. Note that your local building codes may require a sealed spill containment dike around/under the tank. (You can get polypro spill containment units from companies like US Plastics, Global Industrial Equipment and the like.
Reply to
Is this a custom made tank? Most steel tanks for home heating oil are 275 gallon capacity..
At any rate heating oil is classifed as haz-mat, and the tanks must be either on the ground/slab or buried as per building code, unless it's a 5 gallon day tank/transfer pump setup to feed hanging furnaces.
Reply to
Sounds to me like you need to get into the reasons - if we know what the design restrictions are, we may be able to come up with better alternatives that you hadn't considered. Why don't you just want to KISS and pour a simple concrete slab with a secondary containment dike wall around it (or a poly containment tank on top) and put the tank on the ground?
Or build a concrete 'crypt' and slab underground and bury a double-wall fiberglass tank bedded in pea gravel?
If you are trying to cantilever this out over the property line it won't work, you don't have rights to intrude on someone else's lot line just because it doesn't touch the ground. Same thing with lot-line setbacks in the side or back yard that need to stay clear.
The design you propose IMHO looks like it would work IF your foundation wall is poured well-reinforced concrete and way overbuilt now, and IF you put three or four L-brackets across the width of the tank to spread the loads to multiple bolts, and IF you used two bolts at the top of each bracket that went all the way through the wall at each bolt location, AND put big spreader plates on the inside of the foundation wall.
I would also consider a set of vertical supports from the outer end of the L-brackets going down to a concrete footing. Or taking some tension rods UP and anchored to the wall at a high angle overhead or to the roof joists.
Or continuing the tension bolts (or other tension members off the reinforcing plates) inside the basement and catching the floor joists to transfer some of that tension load to the floor.
You are putting one hell of a tension load on the bolts at the top and a lot of overhanging load on the wall. Concrete is not very strong in tension, and if the rebar wasn't placed with this load in mind it probably isn't enough or in the right places. And you are also putting some serious compression load from the bottom of the L into the wall. If it was only vertical load it would handle it.
And NO WAY would I try using epoxy anchored bolts for this. Way too much tension.
I have seen brackets like this used to hang electrical transformers off the wall, but ONLY with through bolts and gussets on the other side of the wall, and ONLY when accompanied by tension rod supports from the outer end of the support arms to the ceiling or wall brackets well above. You need to spread the load out a whole lot more than you are doing here.
Note that I Am Not An Engineer, just a lowly electrician - but my learned experience says this would take a WHOLE LOT of work to make sufficiently safe and sturdy.
And the stuff in the tank qualifies as HazMat - you sure don't want the EPA Guys (Or the Canadian equivalent) in bunny-suits showing up at your front door, saying you get to pay the bill to dig up half your yard to a depth of 10 or 20 feet and ship the contaminated dirt to an incineration facility for remediation... Real Big Bill.
Reply to
Bruce L. Bergman
O.K. folks, thanks for the reality check- in response to your gratefully accepted advice:
Wayne, good point on Boston, I had forgotten about that. I will look into it.
Vaughn, I've used Hiltis & other wedge type solutions in thier various configurations, usually they work, sometimes they don't. Due to the holes proximity to the edge of the foundation I have concerns about their expansion causing cracking.
John & Nick, you are of course correct, the tension on the bolts will be greater due to the longer horizontal vs. the verticle. I can only plead pre-senility brain farts. :( In point of fact the weight will be centered 20" out on the horizontal vs. 14" from the top mounting hole to the bottom of the arm. For all intents the top mount is in a line with the horizontal arm. I'm not sure I buy the 3000 lbs per arm though, my calculations say 250 gallons of oil weigh aproximately 2000 lbs. , or 1000 lbs per arm. (1000x20)/14= 1428 lbs force. Ne C'est Pas?
Et Tu, Iggy? Actually I will get the proper hardware if it turns out the wall will handle it, Hilti has a line of epoxy fasteners that at 3/4" are rated for something like 14,000 lbs tension, other manufacturers list 3/4" at 27,000 lbs.
Steve, I could tell you why, but then I'd Have To Kill You :(. Sorry to dissappoint but it's waste oil, not fuel oil, put your marshmallows back in the bag-
Anthony, the wall is poured concrete, 8" thick. The top mounting holes are aprox. 16" above grade, & one is on a corner so for that one the wall is effectivly 20' thick. This is the "blind" hole I mentioned & why I need something that won't pull out. For the hole that does go through I will certainly have a backing plate of some sort on the inside.
Tony, here in Canada we have Man Sized Gallons. :). Oddly e'nuff I can't find anything in the building codes about mounting oil tanks, & this is on a garage anyhow which they don't tend to get so picky about.
Bruce, I'm not mounting it on the ground for reasons of simplicity, theres only one spot where the tank can go & meet code requirements for distance from exits & the ground in that spot is, to put it mildly, sloped. Even if I excavate there a lot of run-off goes through right there, I'gd really be concerned about the slab shifting, thats half the reason I want it mounted to the foundation. Don't have the $$$ for a vault, don't think they're legal here anymore anyhow.
Looks like I'll have to dig up an engineer to go over this before I do it. If it won't work the way I want I'll probably go with a couple of (deep) concrete posts & supports ( $$$ :( ) for the outboad ends.
Reply to
Howard Eisenhauer
Never said 3,000 pounds per arm. Nick said "Expect the rod tension to be MORE than the weight of the tank", I said "3,000 pounds on the bolts, or 1,500 pounds per bolt, minimum". You'll note we are talking about tension on the bolts, not shear. The shear on the bolts would be the weight only - 2,000 pounds over 4 bolts is 500 pounds per bolt.
John Martin
Reply to
John Martin
My apologies John, that it indeed what you wrote.
Damn Brain Farts Again :(.
Reply to
Howard Eisenhauer
Hi Guys:
I'm going through the current topics to hopefully suggest a way to tag valid RCM traffic.
Add RCM: on the beginning of the title line - BEFORE the obligatory OT?
Hang tiugh - keep posting.
Reply to
cavelamb himself

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