Have you ever designed a rolling trash bin (dumpster)?

[Lomarandil]

So, this is one of those situations where a colleague signed me up to design a rolling trash bin (dumpster) for his site. "That's something structural engineers do, right?".

Yes, the economics actually do work to design one from scratch. Local trash company has a monopoly on the standard ones, and they know it ($$).

So, here I am. I'm sure that I could work out a design given enough time (hah!), but rather than slogging through it, thought I would ask first. Anyone here have relevant experience or suggested resources?

It will be fabricated from thin-wall steel sections and plate. Approximate dimensions 2m x 3m x 1.5m. Only needs to roll about 10m to the curb and back, will be filled and emptied manually (so I don't have to worry about the truck picking it up).

Thanks!

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The name is a long story -- just call me Lo.

 

[berkshire]

Why re invent the wheel?
Talk to these people.

http://www.grahlmanufacturing.com/product-details/2/trash-containers

B.E.

You are judged not by what you know, but by what you can do.

 

[TehMightyEngineer]

If you do go around making one then take a look at McMaster-Carr, they'll have all the hardware you need for small orders (albeit at large prices).

Ian Riley, PE, SE
Professional Engineer (ME, NH, VT, CT, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[Lomarandil]

Thanks guys. This is in Southeast Asia, so the normal suppliers are not in the picture.

Hardware is definitely going to be a challenge!

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The name is a long story -- just call me Lo.

 

[amlinerrichard]

Find a discarded military dump truck. Put wheels under it. I know we left lots of vehicles in Viet Nam in 1975. And more in neighboring countries.

 

[ornerynorsk]

If hardware is going to be a challenge I can't imagine your access to good sheet steel is going to be any better. What about welding, will that be available? Are you going to be relegated to salvage materials? What kind of weight does this thing need to accommodate?

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[SAIL3]

the design loads on a dumpster can vary all over the place....impact loads, abrasion, wear-and-tear, max content loads etc....most of these existing designs are fine-tuned on empirical data and experience....I honestly would not know where to start or end on a design like this and would go to any extent to get an of-the shelf unit...

 

[BUGGAR]

You can look at steel forms for concrete. I'm out of date but there used to be companies like Williams that had some standard gang forms you could study.
The ones I'm familiar with were 3/16 inch skin plate with angle stiffeners, spaced to resist concrete pressure. Designing for full concrete pressure should cover any likely loads.

 

[dhengr]

Lomarandil:
Sounds like a pretty crazy story which could use a bunch more detail and thought before it makes much sense. And, Yup, sometimes Structural Engineers get involved in some pretty crazy designs on a job, as the go-to guys who can do it all. With everyone in the world having an i-phone, you should be able to get a couple photos of what the existing bins look like. What are some of the material sizes and thicknesses, hire a local PhD with a tape measure to get these for you, so you have some starting point. 2m (front to back) x 3m wide x 1.5m deep, that’s 6.5’ x 10’ x 5’ deep, sounds pretty big to me. How many horses is this going to take to move 35’ to the curb (full) and back (empty), not up-hill both ways I hope? Would it be better to have a couple smaller bins, which a couple guys could handle. If hardware is a problem, why not buy a couple hinges and four casters or small wheels and send them over there? Load the bins by hand, yes; empty them by hand too, sounds kinda labor intensive, but maybe fitting for the locale. Do you have to account for the local guy who drops a junk P/U engine in there while fixin his truck, or for heavy construction debris when apartments are remodeled?

 

[Mongrel]

Not a structural engineer, but I drove one of those rubbish trucks for quite awhile.
First of all, as already mentioned, weight will be your biggest issue. And it doesn't matter what sticker you put on the bin, people will put anything in them. And I do mean anything! Which leads onto the issue of moving it, if it does get heavy. To give you an idea - Here in Australia, we rarely go bigger than 4.5 cubic metres for the bins. Those can get pretty heavy when loaded with, say, food waste - the forks on the front of the truck are good for around 5 ton, close to 6 if you know how to work them. And sometimes we still struggled to get a bin in. That's just restaurant waste.
Usually they're made from 3mm Hardox sheet; I understand it's a fairly high-carbon steel. It's quite corrosion resistant, and difficult to tear, but that doesn't stop it happening eventually. Not having to worry about designing the fork pockets will simplify your life a lot - but... how exactly are you planning to empty a bin which could weigh over 6 ton, in normal usage??
The weight and corrosion issues extend to the wheels too, of course. We used steel wheels on most bins, and it was part of the job to grease the axles on these wheels monthly, as part of your rounds. Often the swivels would seize as they would be full of liquid and crap almost constantly. The steel wheels do cut into bitumen and concrete with enough weight, so bins that would run over 1.5 ton would normally be supplied without wheels, or the customer would have to sign a damage waiver.
Consider lid design as well. A simple flat bar with notches cut in it works well as a stand for holding the lids open - these lids also have to be heavy enough to resist wind and animals opening them. Usually the ability to run a simple chain and padlock through them is a good idea. Stops illegal dumping, etc - and people sleeping in the bins. Several times over the years, I've picked up a cardboard bin with a homeless person in it. You really don't want to tip them into the back of the truck and compact them!
Finally, drainage is worth considering. Bins are usually fairly runny. Steel bins need drain bungs for cleaning, or waste water collection, or a variety of other uses. A nice big bung such as the kind used on 44 gallon drums works well. Smaller ones often block up and become useless.

 

[DTGT2002]

Any chance of some channel members?

If you make a structural "cage" of channel members with sheet/plate skin, you probably have a solution. Plate bending theory haunts me and I'd expect a fair bit of deflection is acceptable, as long as the overall structure is functional. More that the plate does not tear apart and the channels/angles/bent plate that make the frame are adequate.

 

[Lomarandil]

Thanks guys! Some good ideas and information here.

Sheet steel will be thin (still tracking that down), so I'll have to have pretty small spacing on the supporting members. (For reference, I just designed some interior partition walls with 0.4mm thick CFS studs. Not quite kosher per AISI.) Such is life. I like the idea of old steel forms, will have to look into that.

Everyone and their cousin can stick weld here (blessing and curse as that is).

As I've looked into it more, I agree that the total size is too large. I'll split the capacity into multiple containers, to make mobility easier. Thankfully, only moving them over level ground. The bins will sit inside a secured site during the day, and need to be wheeled around the wall on trash days. So less risk of stray car engines, construction debris, or occupants. It will be unloaded to the truck by a bunch of guys with paper masks and pitchforks. Probably one of the least pleasant jobs you can imagine, especially in the heat here.

For the frame, I can get light angles (4-5mm thickness) and cold formed channel shapes (0.4mm thickness). I'm sure there are some thicker members around, but will need to avoid them if at all possible.

I appreciate the advice -- keep it coming!

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The name is a long story -- just call me Lo.

 

[SAIL3]

that is surprisingly light and delicate...but the OP may have info guaranteeing the contents and their use that would justify that....