«

»

May 21 2013

Print this Post

Thoughts for David

Thank you so much for your thoughts! You may have just saved the project πŸ™‚

>Some things that would absolutely need to be addressed before the steel thicknesses could be ascertained would be

>1) Maximum allowed load (on both decks!)

Each deck will have at most 50 people. If each weighs an average of 200lbs that is 10,000lbs per deck.

>2) Exact length of the overhang(s)

We have been discussing this quite a bit. The front overhang needs to be at least 4 feet. Ideally it would be 5. I see the front overhang as a transfer station for people to hang out and go down the stairs. I don’t see it as a major dance floor (although people may dance there). The last 12″ – 18″ will hold the top throne that will hold 3-8 people.

We have nixed the rear overhang for people. We may attach a bike rack and some speakers (no more than 500lbs total distributed evenly over a lever of no more than 4 feet).

>3) Absolute maximum span (I would suggest moving the center pair of posts to minimize this as an added benefit would be that you could build the structure with a maximum beam length of 15’ and facilitate up to 5’ overhangs at both the front and rear if desired. If no overhang beyond the deck to the rear is desired I would suggest moving the rear posts forward instead.)

I do not understand this question. Our current maximum span is 11′ 10″.

>4) Total allowable visual impact of bracing on the artistic form.

We want everyone to be safe. Ideally most bracing would be towards the front of the vehicle. The drawings do not show the solid sheer walls we are planning along the steps and between the two front supports. We realize this will not be enough.

We would like to minimize ‘head banging potential’ at the rear. We would like the back area behind the center posts to be as open as possible. The front can contain as much bracing as is required to be safe.

The front overhang can be supported anyway required as it will not take away dance floor space. Please refer to the drawing in the link below:

Drawings 04/24/13

>5) Whether the structure of the flatbed is strong enough to withstand the stresses created by the PMOI of a 10,000 pound dynamic load on a 10’ leverage arm being concentrated into six relatively small attachment points.

I honestly don’t know the answer to that. I have spent a lot of time with the truck and the lower deck definitely feels like it can take what we are trying to throw at it. The reason I hesitate is I am realizing the stresses are not going to be constant and static (as you mentioned, the load will be dynamic). I do not know how to calculate the stresses of a dance floor – especially, as you pointed out, when the weight will be born by 6 relatively tiny points. I was thinking of a static load. Damn.

I would VERY much like to hear your thoughts on this point in particular. I would be happy to research any links you send.

—-

One thing I need to be clear with you on is that the Mutant Vehicles are NOT built up to code. Please look at these guys down south:

Playa Surfers 2013

We want to build so we don’t break, but we are not building to live in it. The most important thing is that everyone is safe. Period. That means safe – not that everything is up to building code.

—-

From David

Ulan,

I would have serious misgivings trusting your potential loads to 11ga especially considering the beam depths and geometry of the structure. The entire floor load between spans will be transferred to the two outer beams creating a twisting motion into the posts at the attachment point to the deck. You have to keep in mind that the frame of the truck and the deck of the flat bed are actually quite flexible and will be moving and twisting with the loads as well. I think that the amount of diagonal bracing and gussets needed would be far outside the design scope for an open feel on the bottom deck.

I have some ideas that may ease construction, lower cost, lower the weight, and facilitate attachment of the artistic elements.

Some things that would absolutely need to be addressed before the steel thicknesses could be ascertained would be

1) Maximum allowed load (on both decks!)

2) Exact length of the overhang(s)

3) Absolute maximum span (I would suggest moving the center pair of posts to minimize this as an added benefit would be that you could build the structure with a maximum beam length of 15’ and facilitate up to 5’ overhangs at both the front and rear if desired. If no overhang beyond the deck to the rear is desired I would suggest moving the rear posts forward instead.)

4) Total allowable visual impact of bracing on the artistic form.

5) Whether the structure of the flatbed is strong enough to withstand the stresses created by the PMOI of a 10,000 pound dynamic load on a 10’ leverage arm being concentrated into six relatively small attachment points.

I know that I’m a little late to the party here and that my involvement would be spotty at best, so I hope that I’m not overwhelming you. I think that everything is reasonably addressable and quite achievable. I guess a good analogy to the load would be a full size heavy duty truck (maybe even two!) driving around up there. That’s rather substantial!

Dave

—-

From: Ulan
Sent: Sunday, May 19, 2013 8:06 PM

We spoke by the fire about the Mutant Vehicle a group of us are building. I am about to order the steel and have a specific question for you.

http://unaverz.com/wp/steel-list-and-qs/

Does this look right to you from an engineering perspective? We are specifically wondering if 11 gauge is going to be thick enough. Any thoughts you have would be appreciated πŸ™‚

PS: We decided to build the vehicle outside.

Permanent link to this article: http://unaverz.com/wp/thoughts-for-david/

Leave a Reply