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1013
1014

Apparently this bridge would work. (imgur.com)

submitted ago by bridge700

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[–]bridge700[S] 90 points91 points ago

A student created this in class today. The program has a history of exploitable features, and exaggerated deflection.

[–]darkscout 19 points20 points ago

Are you sure you didn't select the wrong type of connection type? It looks like they're all connected by a pin that allows rotation vs a fixed pin. or other intersection type.

[–]daStronksie 44 points45 points ago

Bridge design typically assumes truss members, which are pin-pin. This means they can be designed purely around axial load, which is much easier. The problem with this design is it is missing some members, which resulted in the top and bottom halves acting almost independently. Or, the diagonal trusses need to be connected at their intersection points

[–]bridge700[S] 32 points33 points ago

This particular application, West Point Bridge Designer, doesn't allow you to specify. It should have alerted the student that the bridge is unstable, but somehow this design slipped through the cracks.

[–]Bristol_Aero_Student 6 points7 points ago

In our class we made a bridge that droops and looks like a skateboard half pipe. As the truck crosses it, it droops even more, and it even seems to go below the water level. Have you seen this type? I think it is made of lots of Carbon tubes, the biggest kind, built in a very flat diamond lattice from one end to the other.

[–]bridge700[S] 6 points7 points ago

Yes. We call them super saggy

[–]candytime9 2 points3 points ago

I've got a couple files of some crazy bridge designs but I don't have the program anymore. Could I send them to you and you make some gifs? That would be awesome!

[–]bridge700[S] 3 points4 points ago

Sure. But on their website they have a download page for older versions.

[–]candytime9 1 point2 points ago

That's perfect because I'm pretty sure my models don't act as crazy on the new ones.

[–]NorthAve 1 point2 points ago

That brought back memories of my plebe year.

[–]iampinkninja 1 point2 points ago

Memories of grade 9 and 10 for me; seeing if we could make the road stretch off the screen and the truck still drive it. Yes, it can be done.

[–]daStronksie 1 point2 points ago

interesting.

[–]Janus_Grayden 0 points1 point ago

We used that in my high school, it was a lot of fun. I remember having a project where we would actually build our designs with balsa wood and, as such, needed to make the most efficient design with just one type of material. It was a lot of fun.

[–]VFB1210 4 points5 points ago

If I remember correctly from using that program years ago, the exaggerated deflection was intended because students wouldn't be able to see it otherwise. It was buggy as all hell though.

[–]EnderSavesTheDay 1 point2 points ago

Was the student messing around or did they honestly not know how trusses work?

[–]bridge700[S] 9 points10 points ago

just goofing around. I had told them about the exaggerated movement and the glitches. We try to use it in support of understanding truss forces, but they get a kick out of the silly bridges.

[–]EnderSavesTheDay 0 points1 point ago

haha awesome.

[–]p3x447 0 points1 point ago

Apparently this is a standard bridge configuration.

[–]twillstein 104 points105 points ago

"HOT ROLLED STRUCTURAL STEEL SECTIONS SHALL CONFORM TO CAN/CSA G40.20/G40.21-04 (R2009) - MATERIAL GRADE TO BE STRETCHY."

[–]SkyNTP 6 points7 points ago

Not sure if obvious or not, but this has nothing to do with material elasticity. If you look closely, the trusses are built using squares, not triangles.

[–]bijibijmak 2 points3 points ago

It's because the problem doesn't show pins at where the beams cross. The poor student did it according to the problem.

[–]twillstein 3 points4 points ago

I only look closely if I'm liable. Otherwise....semi-pertinent jokes!!!

[–]Red_AtNight 2 points3 points ago

Hello fellow Canadian civil engineer! Let's be friends!

[–]twillstein 1 point2 points ago

Heiiyooooo! Time to network!!!!!!

[–]EbonCoast 1 point2 points ago

As another Canadian civil I approve of this thread.

[–]turismofan1986 1 point2 points ago

clinks pinky rings

[–]truant19 0 points1 point ago

You have multiple pinky rings? That's hardcore.

[–]inedidible 62 points63 points ago

This game is hard http://i.imgur.com/Nc21x.png

[–]wildeye 19 points20 points ago

Let me guess, version 1 wasn't quite sturdy enough?

[–]douglasr007 8 points9 points ago

Nah, we just had a lot of disposable money to use.

[–]CryWolf13 12 points13 points ago

The birds nest Chinese Olympic stadiums cousin

[–]A_Light_Spark 0 points1 point ago

This would be one of those structures very satisfying to see destroyed in a Godzilla movie.

[–]Carlc4 23 points24 points ago

What program is this?

[–]Van_Gundy 45 points46 points ago

Looks like West Point Bridge Designer

[–]blind__man 14 points15 points ago

I'm trying to figure out if this us the program I used about 8 or so years ago. Do they hold annual contests for low cost and high effective bridges?

[–]Se1fer 4 points5 points ago

Yep!

[–]Van_Gundy 2 points3 points ago

Yeah, I remember using it in middle school, and there were national competitions for bridges lowest cost. That was even how we were graded. I don't know if they still do, but I still have it on my computer to mess around with

[–]blind__man 4 points5 points ago

Yes! I remember being the best in my class for this but nowhere near the best overall. That was a really fun program. I'm a computer science major now though.

[–]bridge700[S] 12 points13 points ago

Yes. West Point Bridge Designer 2012 v.2 to be specific.

[–]Tom_Anks 3 points4 points ago

That sounds like fun, I'm going to give it a try!

[–]Tentacolt 5 points6 points ago

I'm no engineer but I'm downloading the shit out of this and giving it a shot.

[–]duckedtapedemon 5 points6 points ago

Also try out Kerbal Space program. Its not nearly as grounded in reality from a structural mechanics point of view, but you build freaking rocket ships and then fly them to different planets WITH PHYSICS. You actually have to know orbital mechanics in order to get anywhere.

[–]Vithar 0 points1 point ago

Well there goes $18, looks fun...

[–]Tentacolt 1 point2 points ago

Sounds awesome! I'll check it out. I've always loved engineering and appretiated it, especially skyscrapers/bridges and giant structures and the like. I just don't have the grades currently to back up persuing it :/

[–]duckedtapedemon 0 points1 point ago

High school or uni?

[–]Tentacolt 0 points1 point ago

High school. I also have other ambitions, it's just something I've always found beautiful. When I'm a millionaire I'll take some classes :)

[–]nmgoh2 2 points3 points ago

It's part of an annual contest. Whoever can design a bridge that will hold the load for the lowest cost wins a full ride scholarship.

[–]Tentacolt 1 point2 points ago

damn

[–]shnnrr 1 point2 points ago

looks fun!

[–]nnorton00 -1 points0 points ago

I think this is Pontifex II

[–]_delirium 4 points5 points ago

Pontifex is probably accurate enough not to let something like that through as a "win"...

[–]HeroOfCanton 21 points22 points ago

Approved! Break ground immediately!

[–]RonnieTheEffinBear 0 points1 point ago

Would you have any idea why I might have tagged you in RES as "guy with a super cool idea"?

[–]lordandrosss 7 points8 points ago

i thought this too, its just flair. but now he's tagged

[–]rudihawk -1 points0 points ago

I don't know, but I have tagged as that as well in RES :/

[–]edu_sanzio -1 points0 points ago

funny... same tag here

[–]ilovecars1987 16 points17 points ago

I had a class which required us to develop the cheapest bridge on the West Point brIdge program. One kid came in with a bridge design that made the truck do a flip when it drove across. He didn't win, but it was entertaining.

[–]rroach 14 points15 points ago

Did... did he pass the assignment?

[–]kirakun 23 points24 points ago

Technically he should. The truck got through. There was no measure for comfort of ride.

[–]spunky_sheets 11 points12 points ago

That truck forgot to get high-centered

[–]cavilier210 11 points12 points ago

How much was the bridge projected to cost?

[–]bridge700[S] 33 points34 points ago

$557,976.54

[–]redditwhathaveUdone 83 points84 points ago

+Damages

[–]ozzimark 11 points12 points ago

Down to the cents? That just makes me laugh.

[–]cavilier210 4 points5 points ago

Nice.

[–]ryumast3r 5 points6 points ago

I think he needs to work on his costs there... I took his design and in 5 minutes made it 3/5s the price

Do I get a prize?!!!!11!

[–]SirNoName 9 points10 points ago

Dynamic stability!

[–]swhell 7 points8 points ago

I don't know why this design isn't used more often

[–]JonLRob 10 points11 points ago

This is not a smartass question, but what makes this bridge better than regular ones?

[–]bridge700[S] 117 points118 points ago

It stirs your drink for you.

[–]TrainOfThought6 24 points25 points ago

Shakes it, really. It's Bond's choice of bridge!

[–]Dstanding 12 points13 points ago

Butt massage.

[–]notkristof 7 points8 points ago

less fasteners :P

[–]nmgoh2 3 points4 points ago

It's West Point Bridge Designer, the basis for an annual scholarship competition. Whoever can get the truck across the river for the lowest cost wins a free engineering degree.

[–]rackball22 -3 points-2 points ago

umm it doesn't

[–]EquipLordBritish 3 points4 points ago

Yeah, I don't think the beams were supposed to expand quite so much....

[–]bridge700[S] 12 points13 points ago

I think it exaggerates deflection by a factor of 100 so you can easily visualize the movement in the simulation.

[–]Stonecutter 4 points5 points ago

Wheeeee!!!!

[–]romantrav 3 points4 points ago

Maxwell would be upset

[–]dr3wsum1 2 points3 points ago

Just downloaded that program. Bye-bye reddit.

[–]diggexpat 2 points3 points ago

When the bridge deformed, the peaks stayed at the same height, and the edges didn't move, so each section had to expand and contract. I don't think solid materials work that way.

[–]betteroffGreg 2 points3 points ago

9/10 would drive on.

Then would puke.

[–]kpanik 1 point2 points ago

Simple, the trusses must make a series of triangles to be constrained. The two end configurations are quadrilaterals which basically makes a 4-bar linkage.

[–]bormax52 1 point2 points ago

I made a few bridge like that back in high school

[–]mkdz 1 point2 points ago

I remember using this program in middle school. It was so much fun!

[–]tikicult 1 point2 points ago

I don't think this is covered under E&O

[–]AdShea 1 point2 points ago

I personally like dynamic bridges that toss the truck.

[–]StraightfromSTL 2 points3 points ago

science, bitches.

[–]VP1 0 points1 point ago

My statics professor just went over this program in class today. Will consider turning in a model such as this one for my bridge design :-p

[–]MTRsport 1 point2 points ago

lol, we had this program in my high school, I figured out how to make the bridge go down at a 90 degree angle almost into the water and then come back up at a 90 degree angle at the end...the truck made it. Watching it make up the vertical distance in the time it should cover the horizontal distance was hilarious, so fast up and down.

[–]Neo63 0 points1 point ago

Wow we just got a project to design and build a bridge with a central support. Challenge accepted.

[–]MJZMan 0 points1 point ago

The truck however...

[–]vulcan257 0 points1 point ago

Ah good old West Point Bridge building contest.

[–]CrocodileMundi 0 points1 point ago

and this is where your professor introduces serviceability checks :)

[–]Mr_Lobster 0 points1 point ago

Oh god, I remember messing with this program in middle school. One class member managed to get the road deck to touch the water from only 1 or 2 heights below the top one.

[–]Juggernauticall 0 points1 point ago

Man, I use to love playing around with that program!

[–]jhchawk 1 point2 points ago

All of these are 1-DOF joints like a pin, some need to be fixed connections.

[–]purdueable 0 points1 point ago

Dynamic Speed Bumps.

Give me the drawings! I'll stamp it!

[–]TheBaconator1990 0 points1 point ago

if society turns their back on civil engineers, civil engineers will turn their backs on society with bridges like this. and then we shall be overlords of the world mwahahahahaha but until then i just want my degree

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