Hi all, I'm working on getting a door cut in an 8" concrete wall so we can put a Theatre Pipe Organ back in our local historic theatre. If we can come up with a way to lift the ~500lb pieces as they are cut out of the wall, we can save multiple thousands off the cost to cut the wall (because they don't have to cut it up int smaller pieces). The hang-up is the hole is 10 feet above the stage floor. Much higher up we have a concrete beam with a nice 8" ledge and the steel grid-work the stage equipment hangs from. it's 16' between the two supports, and the chain hoist will be approximately in the middle of this span. Anyone know how large a wooden beam we will need to safely use the beam to hang a chain hoist.
I've been trying to find info online, but my dial-up connection is really hampering me!
Note the chain hoist. The double 2 x 6 is more than enough to support an engine/transmission. At 16' I'd try four instead of two.
Thanks Steve, but you "cheat" by having diagonal braces, something I don't get to do!
After thinking this over even more, I'm considering having a metal shop build us a bracket we can bolt through the wall above the future door opening to hang the chain hoist--and then later use it for lifting stuff (organ parts) into the door!
I'm awaiting response from the theatre team folks on my "new" idea.
I know this isn't the simple answer that you want to hear, but you're asking a very difficult question.
Unless you buy a piece of highly graded lumber, there are so many flaws (knot holes, spiral grain, compression defects, etc) in ordinary lumber yard wood that it's impossible to calculate the strength of any given board. Especially without seeing it first hand.
By the time you buy a piece of wood that's good enough quality to lend itself to strength calculation, it will be so expensive that you could have purchased a piece of steel.
I would suggest that you go to your local truss company and ask for their suggestion. There are floor beams that are made of laminated material that are quite accurately rated. For a little ten footer of the size that would support your load, it won't be all that expensive. As a bonus, the truss company can probably come up with a table to tell you just how large the beam must be to support your given load.
Call me at (eight05) 489-four078 if you want to talk about this some more.
This may be helpful, or confusing:
This table has engineering properties of dimensional lumber:
This site allows you to calculate the max deflection and stress for a simply supported beam.
With the info on the two sites, you can size your beam. Basically use the second site to enter your loading conditions and the first to get the wood properties.
Length of bean is the distance between the supports.
Load on beam is the total load suspended by the beam. (weight of chainfall + item hanging from it)
Use the Young's modulus number for your wood type from the first site divided by 1000 because the units are psi in the first site and the second is looking for ksi as the input. Young's modulus will only affect the deflection calculation
Distance from the neutral axis is 1/2 the beam height, so for a 2x12 use 5.75".
For a rectangular object, the moment of inertia is 1/12*b*h^3 (b = width, h = height) To calculate moment of inertia use the geometric properties of your assembly. (For two 2x12s, the b=3", and h=11.5" so I=1/12*3*11.5^3 = 214 in^4)
Two 2x12s bolted to each other spanning 16' with a 500 pound load at the center results in 533 psi of stress. Compare that value to the allowable extreme fiber stress in the first site for your type of wood. The number has to be smaller. and the relation between the numbers is the safety factor. (ie, if the calculated stress is half the allowable, the safety factor is 2)
The worst wood in the chart has an allowable stress of 375, the best is 1,500. I do not know what grade wood you are buying. For the worst, you need 4 2x12s bolted to each other would have a stress of 266psi and a safety factor of 1.4.
The best could do it with a single 2x12 and still have a safety factor of 3.
Menards sells 2x12s with an allowable stress of 2400psi, so two of them would have a safety factor of 4.5.
http://www.menards.com/main/building-materials/trusses-i-joists-engineered-lumbe r/pole-barn-post-frame-laminated-columns/2x12-16-2400-msr-syp/p-1466526368994-c- 5660.htm?tid=-7112777838391068674
Long story short is that two 2x12s of any No 1 or Select wood will be more than enough to support 500#.
David, is there a floor on the other side of the wall that you are cutting through? This is what I do for a living... A rigger. We move heavy stuff.
I would set up a cantilevered and counterweighted beam on a scaffold or portable gantry. The chain fall would hang from that. The gantry would be on casters. We would center the pick over the cut and once that slab is cut loose, roll the gantry to the edge and lower the slab to the floor below, onto a dolly.
I can send you pictures of the setup if you wish. I've moved a number of huge pipe organs.
I have a current job where an 1890's house was balloon framed to set a 2nd floor
exterior wall on the mid-span of some 12' pine 2x6's, set at 24 centers. Surprise,
surprise, it has sagged TERRIBLY.
I run all my engineering calculations by the fine folks that sell engineered wood -
Glu-Lams, Strandboard beams, etc. They have all the charts and answers to tell
a user anything they need to know about loads, spans, supports, etc. Around here,
we have several serious lumber yards that sell to builders. You likely have a Probuild
or Boise Cascade in your area (?).
500lbs. is not really that much in building terms. Just our snow load calc's add
40lbs. per sq. ft. to anything we build around here. That adds up quick !
Thank you for all your suggestions! Joe, aaugh Math!!! the bane of my existence (dyslexia!)! I wish I had a photo to show you of the situation, as there are some tight quarters involved. In thinking over the beam placement, which is about 50 feet above the floor, just getting a beam up there would be a project unto itself. I think the bracket mounted through the wall will be my best solution--the wall is 8" reinforced concrete, I think it can take the load!
This all came about because the only bid we had on cutting the hole in the wall is $19K! The guy's reason is that he has to cut the concrete into about 20 pieces to make them small enough to man-handle. If we do this bracket, he only has to cut it into 8 pieces, and the costs will go way down.
Here's a quick sketch of my solution--and the single bolt was just for simplicity, yes, there will be multiple bolts!
We have a donor who builds metal stuff, I think he'll make the bracket for almost free.
Many thanks for all your input, and most importantly, what do you think of this solution?
Oh, and Burger, we don't really have a good lumber supply around here; in this town there is ONLY Home Depot! In Chico there's a little more; a few independents even and a truss shop. This used to be a big lumber area too!
I found a side view drawing of the area, to give you an idea of the working space. We would have to put the beam in near the top of the drawing, so it really would be a major project. I think the wall bracket is much simpler. Sometimes I need to step back and think things through!
I would use a "flitch" beam. That's a beam made up of something extremely strong but flexible, sandwiched between two other things that make it stable by keeping it from bending sideways.
I have made flitch beams using steel plate sandwiched between 2x lumber, and I have made flitch beams using 3/4" plywood strips sandwiched between lumber as well.
A lot depends on length and your budget. Plywood is relatively cheap but only comes in 8 foot lengths, but if you use two or more thicknesses of plywood with the ends staggered, it will do. Steel plate can be bought in any width, thickness, and any length up to 20'.
If you use plywood, glue and nail all the parts together, adding one layer at a time. You could, for instance, start with a 16 foot 2x10, then two pieces of 3/4" plywood meeting in the middle, then two pieces of 3/4" plywood with one cut in half and the 8' piece in the middle and the two 4' pieces at each end. Then either do the plywood thing again, or cap it with another 2x10. As I said, use liberal amounts of glue and nails in each layer, and when it dries overnight you'll have a beam that will easily hold 500# (but will be very heavy)
Or, get a steel plate, say 3/8" thick by 8", by 16', and sandwich it between two 2x8's, with 5/16" bolts in a staggered pattern, every 2'. That should hold 500# easily. This will be lighter, but cost more.
Guys, the more I think about this, the more I realize I would need a sky hook to set any beam in place. Maybe if we had a heavy lift drone???
I KNOW we will go with my second option; drilling a hole in the wall (multiple holes, actually) at 20' up is much easier than handling a beam at 50' (or more) up in the air. Probably the most load we will ever put on that bracket will be the door opening pieces-unless we put the piano in the echo chamber! Even then we could use a lift for that.
Now the only problem is the manager wants this done by Wednesday. . . . Hmmm.
How strong is your concrete wall? A small bolt will pull right through the concrete and tear a big chunk of concrete with it and perhaps the wall depending on the weight. Be sure to use large metal backing plates 24"x24"x1/2" on each side of the wall to spread the pull load out.
Dennis, it's an 8" thick steel reinforced concrete wall. I expect the bracket manufacturer will provide us with the appropriate size and number of bolts, along with a backing plate or load-spreading washers. My drawing is only a concept one.
Who are builders in your area buying their materials packages from ? Home Depot ???
Even if not in your area, I am sure a phone call or fax to a distant supplier can give you
a calculation for your needs.
Good question! Since I'm not "in the industry" I dunno! BUT, the bracket on the wall is the direction we are going!
There are some Package builders in the area, now that I think of it--"Kit" homes basically, but they will custom design whatever you want; Endevour Homes is one I know about. When I needed my storage garage, I bought a "Temporary" steel carport with 4 walls; was the cheapest & fastest way to get my stuff under roof and out from underfoot. Local guy sold it to me, the stuff and crew came out of somewhere "down south" and most of them did not speak English--good workers though and nice guys.