Art Car needs structural engineering help

[aliebling]

We're longtime (10+ years) theme camp organizers doing our first big art car. We have a vehicle and are ready to get started, but need some "real" structural engineer input. The big issue is that we're adding a second level (deck) on the roof of the base vehicle (dodge van body on a half ton truck chassis) and want to make sure the deck will be structurally safe under load.

We envision a supported steel superstructure with wood panels for the floor of the deck, but none of us have direct experience in this kind of engineering...especially when it needs to be passenger-safe.

We're located in the Bay Area (doing the building at Nimby in Oakland) and would love someone to take a look at our (really rough, mostly artistic) design and help turn it in to something structurally sound. Obviously, some gifted time or someone who wanted to get involved as a volunteer would be amazing, but we're willing to pay a reasonable sum if that is what it takes to get this done.

If you have these kinds of skills or just want to volunteer on an art car (or donate!), get in touch. Stay tuned for more from us as the project progresses, too!

[Bay Bridge Sue]

I can tell you this - most of the types of conversions you are talking about involve attaching uprights directly to the frame, beefing up the suspension to handle the load of a second story, and building on the uprights, NOT on the body of the vehicle, as the sheetmetal will not support the weight.

You have to have an idea of what the purpose of the deck will be, the expected occupant load, whether it will be occupied or not while moving, etc... There is also the real possibility, moving the center of gravity higher on the vehiclem, it could tip or fall over. This would be uber-bad. I've seen more than one bus with a deck not being able to occupy it because the bus would fall over if moved... or if the people went to one side or the other. Outriggers on most double deckers are a huge reality on some... again, these would have to be structurally sound, tot he FRAME of the vehicle, not the chassis.

On top of all of this stuff... it has to pass muster of DMV. Just being a double decked party van isn't enough - it has to pass their Severely Mutated rules... they're even disallowing former busses that were regulars on playa becasue you can tell it's a bus. Not seeing your plans, I may be throwing stuff out you've already considered, but it's something huge to consider - I know we're talking more $$$, but it may be worthwhile to pull the van body off and build a custom-purpose body for the unit.

Also remember, once overloaded, your cooling system , electrics, etc. will have to be reworked to keep the vehicle from overheating, going dead, etc. on playa at the 5MPH limit.

But the biggie will be the internal structural memebrs you will need to support your platform, and your anti-tip technology to keep it upright with the top loaded. Above and beyond that, it's basically a decorated deck!

bb

[aliebling]

BBSue,

Definitely down with much of what you say...we were planning on attaching to frame and not the body (for the obvious reasons you reiterated). We got as far as uprights, but really don't know how much is needed in terms of struts, counter-weight, etc... to make it safe. That's what I'm hoping someone can advise us on...the rest of it is at least moderately covered.

And no worries..no one is going to recognize the original vehicle when we're done. The deck is only one part of a larger design...the part I'm least sure about engineering-wise.

[trilobyte]

What BBS suggested, plus if you don't have one seek out a seasoned mechanic to join your crew (or to at least be in defaultia and live vicariously through your adventures). Not just so they know what's structurally sound enough to weld load-bearing steel to, but to make sure the tedious stuff (engine maintenance, transmission work, etc) is covered. Many mutant vehicles make the transformation from well-worn default world trucks, which can mean that just as you're finishing up your wonderful mutation you get hit with a string of annoying stuff.

Congrats on taking the plunge, and good luck with the project!

[gyre]

You should look at anti-sway bars for this application.
You can make this as stable as you want.

A lot of people do this.
Really depends on your use.
The sheet metal will take a heavy static load, so you need to build for whatever use is planned.

[Galaxo Magic]

Last year we took a 3/4-ton Chevy and put a deck on it. We beefed up the front and rear suspension and felt comfortable with 15 people on it. You have a 1/2-ton, getting 15 on could make it unstable if you do not significantly beef up the suspension. Anti-sway bars for sure. Plus if you use a lot of steel for the super-structure, that takes away from the number of passengers it can handle.

We'd be more than happy to talk van's with you, but being in Chico, we probably can't be of any service in person. Good luck!

[laura*]

I can tell you this - most of the types of conversions you are talking about involve attaching uprights directly to the frame, beefing up the suspension to handle the load of a second story, and building on the uprights, NOT on the body of the vehicle, as the sheetmetal will not support the weight.

There's a potetial problem with attaching uprights directly to the frame: A half ton Dodge van chassis is very likely a unibody design with no frame!

(At some weight rating, Dodge did switch to real frame rails. For example, Dodge chassis based RV's have a real frame.)