02-07-2011, 10:18 AM | #1 |
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engineering question
Conditions:
A backhoe weighing 22 tons is on top of a lowboy trailer and heading east on the Trans-Canada near High River, Alberta. The extended shovel arm is made of hardened refined steel and the approaching overpass is made of commercial-grade concrete, reinforced with 1 inch steel rebar spaced at 6 inch intervals in a criss-cross pattern layered at 1 foot vertical spacing. . Solve: When the shovel arm hits the overpass, how fast do you have to be going to slice the bridge in half ? (Assume no effect for headwind and no braking by the driver.) I couldn't solve it either........but who cares; the pictures are great! P.S. The driver was on his cell phone......
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02-07-2011, 10:26 AM | #5 |
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Yep, I would have thought someone from CA would have seen it. I did a search and saw nothing.
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02-07-2011, 10:36 AM | #6 |
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I've never seen it before...it could be old but alot of people never correct the date on their cameras
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02-07-2011, 10:46 AM | #8 |
WTF are you looking at?
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02-07-2011, 10:46 AM | #9 |
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I can't say for sure in this case, but locally we have had events where the arms (or in the case of a dumptruck - bucket), extended in-route. And the clueless driver never bothered looking in the mirror.
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02-07-2011, 10:48 AM | #10 |
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02-07-2011, 11:58 AM | #11 |
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Top Gear trio driving the truck by any chance???
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02-07-2011, 01:16 PM | #12 |
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Damnnnn ...He almost made the whole cut through the bridge.
That would have been even a better scene to watch. |
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02-07-2011, 02:33 PM | #14 |
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We talked about this in one of my classes when we were going over construction accidents, but never discussed the specifics of the crash. You need some critical info: What is the shear strength of the reinforced concrete? What is the yield strength of the hoe arm? What is the surface area of contact between the two? Good luck trying to solve that, it'll be a PITA.
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02-07-2011, 04:39 PM | #15 | |
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Quote:
in addition to that, if i remember anything correctly from my civil eng classes, you'll need a few additional things: -you'll need to know more abt the concrete (pre-stressed, mix, rebar content, etc) to determine its compressive strength -you'd have to model how concrete reacts to the impulse and energy transfer associated w/ an impact (as opposed to the relatively slow, steadily increasing compressive loads that are used to determine its compressive strength)
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02-07-2011, 08:36 PM | #20 | |
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Engineers are some of the best humans. I studied ChemE in school, but now I'm a business guy - moved over to the dark side, I know. I did bust out my old graphing calculator today... it made me feel nostalgic! lol With regards to the pic in the OP... it's pretty amazing how well the excavator took the beating. Even looks like the cab lurched upward cratering the underside of the overpass... but, I guess that the cab is made to withstand impacts. Also, a little eng advice... If there's a CivE on the team, make sure a real engineer is double-checking their work! |
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02-07-2011, 10:01 PM | #21 |
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Civil engineer here, but not sure I want work in this field, not enough creative thought. I'm going to work for a year, feel it out, and possibly go back to school for physics.
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02-07-2011, 10:21 PM | #22 |
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Don't look like it was cut half way, looks like he just got underneath it and stick it up through the bridge. There is no cut on either side of the bridge on top.
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