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Can anyone help me out with a project? I have to get a 60' boom lift from ground level down 10' into a lower level of a building. We will cut a hole in the wall at street level and build a ramp to drive the lift down.BUT......................I am not sure of my design and how much it can support.My plan is to build a triangle "Truss" that is 10' tall on one end and tapers to the floor over a 20' distance. I will drop 10' in a 20' span. I know the lift can handle the angle but not sure if the ramp can handle the lift.The plan is a 10' wide X 10' tall X 20' long ramp. All built with 1/4" angle iron 3"X3". I will build four half trusses (triangle) for support. these will then be cross braced every four feet to keep them from folding over and collapsing. Then the top will be covered with 1/4" plate. I will space out the trusses so the wheels of the lift ride right between two trusses on each side.I am very confident of my welding abilities but not in my ability to know how much weight my design will hold.See the image and offer suggestions please.This will be used for a demolition project (we have not been awarded the job yet) and probably not used again (unless I can talk the boss into giving it to me ). Attached Images
Reply:looks prety solid to me but why did you only triangulate in one direction ??all the truss i have ever seen go to both directions. probly the best thing to do would be get an engenear to figure it out for ya. maybee the local collage could help ya out. depending on the LBS involved here a lil mathmatics is involved to insure a safe move. if its bit time lbs guessing is not a good idea. could result in a lot of this Attached Images summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:I would give a quick call to a structural or even a truss engineer. One might give you a better idea of what will work without the consult fee. That is alot of weight to move. I'm not sure if it's a good comparison but my 32 foot truss' were rated at a snow load of 80 lb/sq.ft . Your potential project would be pushing 25,000 pounds over an area of 400 sq. ft. I think that is roughly a load of 63 lb./sq.ft. Your design may work.John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:Bob,That's pretty steep, a 26.6 degree angle or a 50% slope. Are you -sure- that the boom truck is rated for that steep of a slope? Going down -and- coming back up? Call the boom manufacturer and ask them what the vehicle slope limits are.Going to a 30-foot horizontal distance gives you an 18.4 degree angle. Even going out 25 feet drops the angle to 21.8 degrees.Without going into a complete truss analysis, I'd say NYET/NOPE to making that ramp out of 1/4 inch thick material. Either the angle-iron or the plate. That much weight on that thin of a material just seems scary.And 3x3 angle iron? Nope again.What thickness steel plate do road crews put down over trenches or holes temporarily? It sure isn't 1/4 plate! Go for 1/2 inch plate at least. I'd say to make your structure out of C-channel at LEAST 4 or 6 inches wide. And I'd cross-brace the truss members because a 10-foot long skinny piece of steel is going to try and buckle.As a point of comparison, a quick check says that a column to support 25,000 pounds is BARELY adequate if made out of hollow structural steel Grade A500-GR.B-46 4x3 rectangular tube with 3/8 inch thick walls. Having the multiple vertical members will give you a safety factor, but even that wouldn't be a big enough safety factor to meet typical bridge/building/structure requirements of Fs=10. No way is 3x3x1/4 angle iron going to cut it.Does the firm have a PE? That should be his/her job to design this, not yours. No slight to you intended.And MicroZone, your roof snow load of 80 lbs/ft2 is a static evenly distributed load. A moving vehicle on a ramp is not evenly distributed weight across the entire surface area and if the vehicle is moving then the load sure is not a static load!Last edited by MoonRise; 01-24-2007 at 02:00 AM.
Reply:Any room outside to dig down a dirt ramp and then breach the basement wall? Seems a good operator could do that faster than you could fab up the frame, and cheaper (considering your materials cost). Of course, then you make no $$. If somebody's life is gonna depend on it (the boom driver), then have it engineered for hire. Let somebody else buy the liability on it.Once it's in place, for the duration it's in there, who else will run who knows what down it?Just thinkin' out loud.
Reply:Moon - you are correct, it is a static snow load. His potential project is a moving load, very different.John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:BOB Your ramps are plenty strong for 25.ooo lbs.
Reply:Does the approach angle allow sufficient ground clearance for the lift truck?
Reply:kaiser715 - That was my first recommendation but the company killed that immediately due to utilities burried there. That option is out.I am considering changing the design of the ramp based on a design by a company that makes what is called "Yardramp" and they make a great ramp but unfortunately they do not make them wide enough for my application. If I could find any I could maybe use two of them together. Otherwise I could build one myself for the job. I found one locally (20,000 lbs) that belongs to a company that I could use as a model for a wider, heavier version. I am contacting the company for options.http://www.handi-ramp.com/yardramps.htm
Reply:That seems like a good viable option. I figured a ramp of that size would be hefty - some of their 25k capacity ramps weigh in between 4,700 lbs. and 6,500 lbs. You'll need something heavy duty to put those in place as well...unless you build them in place.John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:Bob,I'll repeat some of what I said above.No slight to you meant or intended, but this sort of task needs to be designed by a pro. As in Professional Engineer. And the PE should be familiar and competent with structural steel. He or she designs it, calculates everything, and puts their stamp (literally, in case you didn't know it they will have an embossed PE stamp to mark the drawings with) on the job and gets the design liability for the job.I've seen some of your tooling on your website and it's pretty darn good and nice. Your proposal for the ramp to build it out of 3x3x1/4 angle iron is not even up to the same level at all.There is a BIG difference between welding up something for your own use, and designing something for public use or use by someone else. And a big part of that difference is the LIABILITY. Designing a structure is sometimes straightforward, and sometimes there are some guidelines or building codes to guide you. But your task here is not within the scope of usual building guidelines for a layman or a tradesman to do.Using angle iron for a structure is not good, the failure mode(s) of angle iron are sometimes funky and very sudden. For instance, angle iron will twist and buckle and suddenly the resisting cross-sectional area for the load pretty much disappears and you then have a catastrophic failure.Don't try to design a ramp or bridge yourself. You are not a structural engineer. Let a PE design it and have the liability and responsibility for the job.For instance, what will happen to the bottom end of this ramp when 25,000 pounds of vehicle is on the ramp? You're going to need structural footings for your structure. How is the top edge of the ramp going to be tied to the street level? If it's not tied in structurally, as soon as the load is on the ramp then the top edge is going to deflect and a gap will form. That gap will be a 13-ton+ shear to anything that gets into the gap. And I was not kidding when I said you would need to have a typical design safety factor of 10 for a structure, unless a PE carefully analyzes and designs everything and takes the liability for the structural design.Let a PE design the ramp.Let a PE design the ramp.And I'll say it again in case you missed my point.Let a PE design the ramp.Or rethink the process of how to get the truck down 10 feet. Dirt ramp, or maybe have a crane just place the truck where you need it, some other way to do the task.
Reply:I don't understand why they want to move it down one level. If they're going to take it out, take it out of the building completely and set it outside. They are going to move the unit one level then demolish the rest of the building around it?John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:Look at it this way, if you design and fabricate the ramp and it fails and someone gets hurt, you are through. Insurance companies will be lining up to get a piece of you for a long time. Rethink the way you are going to get the boom down or get a PE involved.
Reply:Just for those that are not understaning the project.We are going to demo the inside of an auditorium. The floor of the auditorium is 10' below grade. The inside of the auditorium has theater seating, so all of the rows of seats are elevated several inches above the one below it. We need to demo the entire 6075 sq. Ft ceiling which is plaster and lathe. The only safe way to do this is with a lift. Since the theater syle seating limits the floor access to the center of the room, you would need a LONG boom lift so you can reach all area of the roof for the demo. A scissor lift will not work because the levels where the seats are are too small. Scaffolding is a PITA and would be really slow, raising the cost considerably. I am not willing to hang people by harnesses to do the job.
Reply:Bob, Once the side of the building is opened up, why not back up dump trucks and build the ramp with gravel. A skid steer could advance and place the material as the ramp grows. In order to save some clean up (and gravel costs) perhaps you could have the "sides" built with concrete form sections, this would define the sides of the ramp, and probably make it build up faster too.Just my opinion, not from a book, just from the road.Howes Welding Inc.www.howesweldinginc.com
Reply:Bob,The building itself stays intact, the seats and stepped floor stay intact, everything is pretty much left alone except for the 6075 ft2 plaster and lath ceiling?Hmmm, that's a square 78 ft, or a 75x81 ft rectangle. What's above the ceiling? Can you get access from above and take the ceiling out that way? How high is the ceiling? Maybe instead of putting a boom lift with a 60 foot boom on it in there, you could drive a scissor lift or two in there and just build localized temporary flooring over the seats. If the seats are getting replaced, yank them out and put the temporary flooring on the existing floor.Block up and extend a seating level across two or three or whatever rows and put the temp flooring in and run your scissor lifts on the temp flooring.Or if the seating all goes and just the concrete stepped floor stays in place, bring in gravel and some skid-steers and make gravel paths spanning a few seating tiers at a time. Run the scissor lifts on that. Conveyor-belt the gravel out and re-use or resell it.Last edited by MoonRise; 01-25-2007 at 04:57 PM.
Reply:i would almost bet you could get the lift delivered on a tilt and load truck that would have a ramp that long on the back of the truck..and that they could tilt the bed of the truck and let it in the hole for you...or rent you some sort of ramp for your specific application
Reply:The boom lift is out. The school just killed the idea of opening the wall.The ONLY way into the room is to go through the school and in the regular doors. The floor is marble and cannot handle much weight without cracking.We may be stuck with scaffolding and working slower.
Reply:sounds like more truble than its werth, why so picky on how it gets put in ?? any wall or flor can be repaired or replaced. they must not want this thing too bad if they are not willing to do much to acomidate moveing it?? summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:You would not believe some of the requirements they put on you.
Reply:just dump it on the front lawn and tell them " here its yours now you figure it out" then you will see how bad they want it LOL.any thing dealing with the state or even higher levels of the goverment can be a real pain thats for shore.been there done that. summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time. |
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发表于 2021-9-1 00:34:42