# WATER BRIDGE . OVER A RIVER!!!



## Kipper (Nov 13, 2006)

Have you ever seen a WATER bridge over a river?

Even after you see it, it is still hard to believe !

Six years, 500 million euros, 918 meters long.

This is a channel-bridge over the River Elbe and joins the former East and West Germany, as part of the unification project.

It is located in the city of Magdeburg, near Berlin.

The photo was taken on the day of inauguration.

To those who appreciate engineering projects, here's a puzzle for you armchair engineers and physicists.

Did that bridge have to be designed to withstand the additional weight of ship and barge traffic, or just the weight of the water?

View attachment 211


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## Guest (Nov 13, 2006)

Kipper --

Very interesting indeed.

I am not a structural engineer, but I slept at a Holiday Inn 

My thought is that the water over bridge design would need to account for weight of the additional traffic. Archimedes Principle states, in short, that the buoyant force on a submerged object is equal to the weight of the diplaced fluid. The displaced fluid prism that represents the equivalent weight of shipping traffic is contained, or perhaps better stated - supported within the water over bridge structure (channel) - hence the combined weight must be accounted for when evaluating loads. '.02'

JR


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## Mike1144 (Nov 13, 2006)

Have you seen that rotating water elevator in Dunkirk? They had a show about it on Discovery. That thing was crazy pointless.


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## tmckeon_PE (Nov 13, 2006)

Just the weight of the water (displacement...did I just qualify for an armchair engineer position?).


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## singlespeed (Nov 14, 2006)

Unless it's on a airplane on a treadmill which is also on the barge, you have to account for the weight of the shipping traffic :rotflmao

I feel a long thread coming on


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## DVINNY (Nov 14, 2006)

if you have a closed system, meaning there would be locks at the end of the bridge, and you add any additional weight with boats it'll still add weight.

if it's an open system, meaning the water can push freely to either end of the bridge (displace) then the boats will not add any additional weight.

No need to argue this one, there is not a conveyor involved.


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## Mike in Gastonia (Nov 14, 2006)

> if you have a closed system, meaning there would be locks at the end of the bridge, and you add any additional weight with boats it'll still add weight.
> if it's an open system, meaning the water can push freely to either end of the bridge (displace) then the boats will not add any additional weight.
> 
> No need to argue this one, there is not a conveyor involved.



But if you have an automatic water leveling device that keeps the level of the water constant and water is pumped out (if you have a closed system), then the ship wouldn't add weight.


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## DVINNY (Nov 14, 2006)

Wouldn't that device make the system "OPEN" by definition?

Good shot at Devil's Advocate though. LOL.


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## Road Guy (Nov 15, 2006)

all I know is those intermediate bents (piers) look pretty freaking large...

where is this at? i didnt know traffic was so bad on waterways that we needed grade seperated rivers?

Maybe there is a whole new market for traffic engineers to work in..


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## Kipper (Nov 16, 2006)

> Just the weight of the water (displacement...did I just qualify for an armchair engineer position?).


Sorry! I meant to take that part out for this group. 



> all I know is those intermediate bents (piers) look pretty freaking large...
> where is this at? i didnt know traffic was so bad on waterways that we needed grade seperated rivers?
> 
> Maybe there is a whole new market for traffic engineers to work in..



It is located in the city of Magdeburg, near Berlin.

If the water level is raised by the diplacement of the boats and passengers, and you design for the weight of the water at that level, then aren't you using the weight of the boats and passengers?

It looks like there is a conveyor under the water going in the opposite direction so are the boats going to go any where?

Hopefully MA PE will put in his '.02'.


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## DVINNY (Nov 16, 2006)

> If the water level is raised by the diplacement of the boats and passengers, and you design for the weight of the water at that level, then aren't you using the weight of the boats and passengers?


BINGO!!!!!!


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## Guest (Nov 16, 2006)

> If the water level is raised by the diplacement of the boats and passengers, and you design for the weight of the water at that level, then aren't you using the weight of the boats and passengers?


Ooooohhhh ... I see your logic :duhh:

Do I at least get partial credit for recognizing the governing principle despite my less-than-stellar ability to articulate the proper response ??!! :w00t:

JR


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## Kipper (Nov 20, 2006)

> > If the water level is raised by the diplacement of the boats and passengers, and you design for the weight of the water at that level, then aren't you using the weight of the boats and passengers?
> 
> 
> Ooooohhhh ... I see your logic :duhh:
> ...


Any regular member on this board gets a pass.

AND yes DV I said member. Get your mind out of the gutter.

I watched all three Austin Powers movies...finally.

Still :rotfl:


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## PEsoon2B (Nov 20, 2006)

What about a junior member?

I've heard the old saying "It's water under the bridge"

I guess this makes for a new saying.


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