Steel Plate Deflection

[NetDave]

Is there a way to find out how much weight a steel plate can hold? Is it better to use hardened or standard? Looking to use 1" thick plate, 8' X 12' and cover a hole approximately 6' X 10'. Any help is appriciated.

[PinkertonD]

Hi Dave and welcome to the forum.

What kind of loads are you anticipating on the cover? Is it going to be a point load like a rear wheel of a tractor, or is the load going to be distributed evenly over the entire areas as in dirt and grass? Are there going to be holes in the cover?

Using 1" steel plate is going to be the most expensive option compared to a welded mechanical truss approach and maybe 1/8" or 1/4" plate skin depending on loads.

You can get varying toughness grades of steel, but not really hardened. Generally the tougher grades are used or damage resistance rather than integral strength so probably a general use Mild Steel sheet would suit the purpose. Before we go calculating the thickness required, we need to know a lot more about what is, or might happen with loads.

If there is a risk to humans passing over it or under it, then it is doubtful you will get a lot of assistance here as we would recommend a Structural Engineer be employed as there will local Codes to be met.

{edit}
Just did a quick check and a 1" x 4' x 8' hot rolled steel plate runs to about $1800 and you will need three of those as I am not sure you will easily find an 8' x 12' in one piece.

[NetDave]

PinkertonD,
Thanks for the assistance. I work in a welding shop/hauling company. We are trying to cover an uneven surface that is causing a roll off truck to lean heavly to one side. It is a water run off area so and is way over graded towards the drain. My fear is the truck rolling as it is lifting the loaded container. The entire area is concrete so I would be able to anchor one side of the plate. While the other side I believe would have to be supported. Weight wise, a loaded truck will be right around 25 ton. This is a maximum weight that it should see. Only half of the truck will be on the plate.

I was able to locate a 1" X 8' X 12' for $3,130.

[RWOLFEJR]

First thing that pops to mind is to cut out the floor... build a form and re-pour. If you could re-grade the entire area you might eliminate a lot of extra B.S. too. It doesn't cost much to move dirt around and could reduce the amount of your pour and eliminate having a wall on the low side...? If you can't re-grade... On the low side build a form for a nice wide curb that'll stick up past your level finished floor height by about 6" to a foot? Might need a railing there too? Then pour a level floor... $3,130 will buy a lot of mud. If necessary maybe incorporate a drain system before you pour. Maybe some steps somewhere on the side that'll be a wall... With 25 ton running over this I'd go about 8" minimum thickness and pay the extra 10-20 bucks a yard and go with the fiber reinforced concrete.

If this roll off truck you're talking about is what I think it might be... The big steel boxes with the steel wheels? Big scrap hoppers? If this is what you're rolling on this section of floor I'd embed steel plate in your floor where the wheels will run. Maybe 1/4" thick x 2' or a half sheet? Otherwise those wheels with their line point contact "can" destroy your concrete. You get one wheel just slightly out of whack and they'll dig grooves in your floor big time. You can re-bar plates in position and shoot them in before you pour so they're anchored well. Then your man on the float can just dress to the plate tops.

Second choice runs through my head would be to build several sort of truss wedges and anchor them to the floor then throw your plate on them, but I wouldn't go this route unless you're restricted in some way that wouldn't allow you to just re-do the floor.

[NetDave]

Thanks RWolfejr. This has been a huge help. You are correct with the truck your talking about. The issue we are having is the problem is on a customers site. I spoke with them about repouring the area and they laughed in my face. When I spoke to our people about the several safety issues it seemed as if all they were concerned with is keeping the customer. I like the idea of the truss wedges. Simple, strong and safer than just outside bracing.

[RWOLFEJR]

Hmmm...
That's a horse of a different color...

Seems as though you might be between a rock and a hard place.... or "our people" and "their people" as it were. This sounds like a very sticky situation with too many details involving both legal and moral obligations or requirements. I don't know what your position is in this matter is but I'd tread softly and swiftly and most importantly... make sure my butt was covered before doing anything.

Good luck,
Bob

[NetDave]

Bob,
You are spot on with that statement. I run the weld shop and have been in agreement with the route manager saying we need to drop the customer. Unfortunate.... but it could save loosing a truck. CYA'ing all the way is tough with a situation like this one. Thank you again for all your assistance. Dave

[PinkertonD]

Dave,

Is it your company's truck? What about a couple of hydraulic outrigger jacks on the truck such as cranes have, to lift the down-side up level before the lift? I assume you already have hydraulics for the lift?

Just thinking out loud as I am not sure I know the kind of truck you are talking about.

[RWOLFEJR]

Yes... I Like it a lot. (To be said in voice of Forest Gump...)
Beauty of the outrigger approach is it could be useful at other customers somewhere down the road as well. Might be your easiest sell to management too? You might start by looking around at crane companies or in used equipment rags and possibly find a good units or rebuildable one? Every rigging company I know of has some old beasts in the back for parts or decoration...?

[NetDave]

Thanks Guys. I spent the weekend coming up with a couple different outrigger designs. I'm going to set up a meeting this week to present everything I've found... (with all of your help!) Lets hope for the best!!! Thanks for you assistance.

Dave

[PinkertonD]

I'm going to set up a meeting this week to present everything I've found...

Would love to hear how it all turns out , Dave.