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Bridge fail video in the works?

3,137 Views | 25 Replies | Last: 4 yr ago by BuddysBud
Serious Lee
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this is crossposted from a thread on tigerdroppings.

Quote:

Bridge span is 30 feet. My grandfather put some steel beams across it in the late 1940s. They're about 12" tall and 8" across (not sure the proper way to describe those dimensions).

There are four total beams. Two pairs about two feet apart. And about 6 feet on centers.

I decked the bridge with full cut 3x10" pine.

Log trucks will be 80,000 pounds. But only half the load will be on the bridge at any one time. I guess the rear axle might carry more weight, so maybe a max of 45-50,000 at a time.

Here are some photos. Thanks for your thoughts and advice.








rally-cap
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AG
texAZtea
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I'm no engineer but....
actually that's all I have to say. I'm looking forward to someone explaining this though.
WC87
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YOLO
SanAntoneAg
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He decked the bridge with pine boards?

The guys pictured don't look like your typical coonasses.
ttha_aggie_09
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SanAntoneAg said:

He decked the bridge with pine boards?

The guys pictured don't look like your typical coonasses.
What do you mean???? His name is Leaux-pez

And yeah, that is sketchy...
v
CS78
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.
AggieChemist
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It'll probably be fine. There's a bridge here in WV that I've been over a dozen times that's decked with 2x4s. It's 150 feet above a class five whitewater river.
TxSquarebody
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Send it!
AgEng98
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The decking is the least of my concerns in this situation...
Ragoo
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Max deflection = L/360
Deflection = load * Length cubed / (48* section modulus * moment of inertia)

Simple calculation
Lt. Joe Bookman
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Id think you would want to know more about the foundation and piers (if any) the I beams are mounted on.
jetescamilla
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Note: I am not your engineer

Based on your dimensions I can assume your shapes are roughly W12x40's. With a very very rude back of the napkin check I would not run log trucks across this bridge. Did 1 or 2 simple calculations and it doesn't look good. On top of that spanning 30ft for these small shapes is longer than any design charts I have, this indicates that these shapes are pushed beyond what they would normally be for structural use.

If you're looking at taking across sizeable loads hire an engineer to run some numbers for you. Not to "work gloat" but I am a professional engineer who specializes in bridge design...so take that for what it's worth.

$3 Sack of Groceries
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I am not an engineer but I work closely with them. I also like to watch stupid people make mistakes on the internet. Please continue as planned and stream video direct to the internet.
Charismatic Megafauna
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Probably be alright as long as they hit it with some speed. Srsly I've seen loggers do silly stuff with fully loaded trucks, not even counting what happens on public roads.
Seems they could put some temporary support underneath for the logging operation, like building an a-frame under the middle out of drill stem, or just toss a pad on top...or both
*i am very much not an engineer
gomerschlep
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Ragoo said:

Max deflection = L/360
Deflection = load * Length cubed / (48* section modulus * moment of inertia)

Simple calculation
Beat me to it....
Was totally just about to post this same thing........
texags08
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This has "drive a Jeep around Africa" potential.

FamousAgg
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Engineer here, I say it will make it.
rootube
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After careful analysis here are my key observations.
OverSeas AG
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Every knee shall bow and every tongue shall confess
Naveronski
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In
BuddysBud
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rootube said:

After careful analysis here are my key observations.



I don't know, the light rays are aimed at the "don't drive on this part" of the bridge.
The light might have a different meaning. For example, "If you drive on this part, follow the light to heaven."
Centerpole90
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Andrew wrote his name in the concrete...

That's good; that way the truck driver's widow will know who to sue.
Daddy-O5
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I'm not an engineer and I don't really know what's going to happen here, but I'm in anyways.
Thanks, and Gig 'Em!
jellycheese
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I always love when people ask if it will work after they commit to doing it.
rally-cap
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Walt Luddiger said:



And everyone knows, the best place for a spliced beam connection is right in the middle of the beam's span!
BuddysBud
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rally-cap said:

Walt Luddiger said:



And everyone knows, the best place for a spliced beam connection is right in the middle of the beam's span!


Since I am not an engineer, I was wondering if those 1x1's would hold up under 80,000 lb logging trucks?
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