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  • Concrete thickness required

    Hi all

    I'm taking delivery of a new shear in a few weeks. The machine weighs 14,000 lbs, and has 4 feet 12in x 4 3/4in. My shop floor is anything from 4 to 6 inches with rebar of unknown spacing & quantity. Any ideas on required floor thickness. By the way it is not a Chinese machine.

  • #2
    If it's a new shear the manufacturer should be able to give you recommendations.

    Not knowing how much rebar or what kind of soil or what soil preparation was done makes guessing somewhat harder.

    Steve.

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    • #3
      The quality of the cement pour and positioning of rebar within the thickness of the slab and compaction of the base is history and cannot be changed. The first compensation would be to distribute the load with plating/planking. If there proves to be a problem which I kind of doubt a section of floor can be removed beefed up and repoured.
      Byron Boucher
      Burnet, TX

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      • #4
        If it's setting equally on all four feet that's only a little over 61 psi.

        I have no idea about concrete's load bearing, but that sounds like it should be easily handled. ...if as said, there're no voids or surprises underneath.
        Is it relatively new concrete?
        Lynn (Huntsville, AL)

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        • #5
          Hydraulic shear I assume since it's new.Hydraulic shears aren't nearly as rough on foundations as the older mechanicals.4" should be plenty assuming it's on a good fill base and it's intact with no cracks in the footprint of the machine.
          I just need one more tool,just one!

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          • #6
            Originally posted by klemchuk
            Hi all

            I'm taking delivery of a new shear in a few weeks. The machine weighs 14,000 lbs, and has 4 feet 12in x 4 3/4in. My shop floor is anything from 4 to 6 inches with rebar of unknown spacing & quantity. Any ideas on required floor thickness. By the way it is not a Chinese machine.
            I would have the base engineered. In any event, I would pour at least 12" thick, and have the base extend at least 12" beyond the feet in both directions. Those shears put a large dynamic load on the soil every time they cycle. The vibration from the shop shear, at one food processing plant we did work for, was so bad they removed it, cut the floor out, and then installed a new base that was isolated from the rest of the floor slab by 1" Dow blueboard insulation. The vibration of that shear cycling could be felt thorugh the floor slab, hundreds of feet away. That base , as I recall, was 14" thick, and had 2 mats of #6 rebar top and bottom.
            Jim

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            • #7
              A big shear is as much a machine tool as an engne lathe when it comes to the nesessity for alignment and the accuracy of its operating parameters. Over a certain size a foundation becomes necessary and a 16,000 lb shear is well into the category. I suggest you select a site, saw the floor, dig down a couple feet, set a cage of re-bar, pour with concrete. and trowel flush with the floor. I don't think you need an isolated foundation unless neighboring equipment will be affected by the jolt of its operaton,

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              • #8
                Something else to consider, if you don't get it engineered....
                The center of gravity of the unti is probably fairly symetrical from side to side, but many of these units are much heavier towards the rear of the footprint. If you look at the mass from the end, you want the foundation to be roughly centered under the center of the mass from front to back. Usually that means the footing projects farther out the rear than out the front.
                Jim

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                • #9
                  New shear 1/4" x 8' hydraulic

                  Steve F
                  Manufacturer says 5 to 6 ins would suffice.
                  Construction website says 3000lbs per foot

                  Boucher
                  Plating with 1in material is looking good right now.

                  lynnl
                  Concrete is questionable as to voids, as I know the builder of this complex.

                  Wierdscience
                  No cracks as yet. Building is 15 yrs old.

                  Forrest Addy
                  Company techs are coming to set up machine.

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