Bridge Design Challenge

[SunBat]

Yeah. Like that.  However, if you are going to use battered piles (piles may not be needed) you may as well batter them in the direction of the load.

EDIT:  You changed the picture. The first way was much better.  Now your arch is taller than necessary.

[Dadsguns]

Elaborate please.  (If you can)

Relax, just jerking your chain.... hence the devil

Here in Hampton roads area they have several tunnels that go deep under water so that it does not interfere with shipping, very amazing since it has the harsh added element of salt water, not sure if your model depicts salt water or fresh, but my option would have been to construct a tunnel as to not interfere with shipping.   

[Babalonian]

Here is my bridge, I jsut took off and did this in 5-minutes.  Sorry if it's similar to someone elses already.



It's concrete (precast if possible, a lot cheaper than steel).  Two things, particularly mindful of project cost, that I think you didn't address Grizz:

1)  It's Cut & Fill.  Most places these days it costs near a fortune to dispose of (or an arse-load of luck finding a happy taker of) fill/dirt.  It is considered a cost-saving/VE/LEED/$$$$ goal of clients to not have to have to pay for any additional disposal, trucking/transportaion, associated fees, etc. when you can logicaly use 100% of any displaced dirt from any cutting.  It's trading the cheaper cost of X-inches to build the bridge higher in exchange for the cost of not having to transport and dispose of Y amount of fill.

2)  Pay mind where possible to build piers where water levels won't be during construction (cheaper), and also not to build them in the deepest parts of a river.  I find my piers strike a good balance, wont be too big or expencive to construct, and also will allow for smaller/cheaper foundations for the bridge (I think in your basic design, they would need to be rather large foundations for the large spans).

[grizz441]

Here is my bridge, I jsut took off and did this in 5-minutes.  Sorry if it's similar to someone elses already.

(Image removed from quote.)

It's concrete (precast if possible, a lot cheaper than steel).  Two things, particularly mindful of project cost, that I think you didn't address Grizz:

1)  It's Cut & Fill.  Most places these days it costs near a fortune to dispose of (or an arse-load of luck finding a happy taker of) fill/dirt.  It is considered a cost-saving/VE/LEED/$$$$ goal of clients to not have to have to pay for any additional disposal, trucking/transportaion, associated fees, etc. when you can logicaly use 100% of any displaced dirt from any cutting.  It's trading the cheaper cost of X-inches to build the bridge higher in exchange for the cost of not having to transport and dispose of Y amount of fill.

2)  Pay mind where possible to build piers where water levels won't be during construction (cheaper), and also not to build them in the deepest parts of a river.  I find my piers strike a good balance, wont be too big or expencive to construct, and also will allow for smaller/cheaper foundations for the bridge (I think in your basic design, they would need to be rather large foundations for the large spans).

Thanks Bab, I like that idea of a 4th pier also.  That might be more cost efficient than 3 piers all things considered.

Zoom, phatzo, your ideas are much appreciated also and while they are scaled appropriately, I don't think they are cost efficient for this span length so I probably won't be looking more closely at them.  Besides, I have barely any bridge experience as is and even less "innovative bridge design" experience so I'll probably have to stick to girder bridge.

[Babalonian]

Thanks Bab, I like that idea of a 4th pier also.  That might be more cost efficient than 3 piers all things considered.

Zoom, phatzo, your ideas are much appreciated also and while they are scaled appropriately, I don't think they are cost efficient for this span length so I probably won't be looking more closely at them.  Besides, I have barely any bridge experience as is and even less "innovative bridge design" experience so I'll probably have to stick to girder bridge.

If only every bridge designer/engineer in the world had an unlimited budget on every project.....  sometimes ya get lucky though: http://en.wikipedia.org/wiki/Sundial_Bridge (gorgeous (and ingenious) bridge IMO though if ya ever get the chance to see or study it).

The Sundial Bridge is a cantilever spar cable-stayed bridge for bicycles and pedestrians that spans the Sacramento River in Redding, California, United States and forms a large sundial. It was designed by Santiago Calatrava and completed in 2004 at a cost of US$23,500,000. The bridge has become iconic for Redding

That's taxpayer money baby! (albeit one of the nicer uses of it)



Day


Night

[Dichotomy]

 

AWESOME!!!!

[5PointOh]

Here ya go Grizz.  Both of these are rather cheap and easy designs. Not much for city ascetics, but very functional. I'm more toward the second on as the lacking of post prevents river flow or river traffic for commerce.

First: Under truss design.


Second: Arch Design.

[kilo2]

[Killer91]

I'm thinking why even build a bridge. This would be allot more fun 

[rpm]

I was thinking the same thing, only taking more of a Wyle E. Coyote influenced design using catapults.

[grizz441]

rpm and killer, I lol'd 

kilo I'm definitely going to look into that sloped crossing.  It looks steeper than it is based on the scale differences.

5pointoh, that steel one is pretty similar to my layout but I think as far as girder bridges are concerned, prestressed concrete is cheaper and more efficient so I'm going to go with that.  The arch bridge I'm going to stay away from due to more difficulty in analyzing it and also it will probably be less economical at that span.

Thx for the contributions though guys, I will keep you updated when I solve which girder bridge and with which pier arrangement will be cheapest of the ideas posted.   

[Dichotomy]

 

Good thread Grizz...

A good Engineer and a good designer are always interested in looking at alternative ways to do things AND looking into areas that are not their primary discipline.  This thread had me talking to a couple of my PE's this week and watermelon chatting about this and that.

[2bighorn]

It looks steeper than it is based on the scale differences.

If you adjust for scale (height/length) you can quickly figure out that any type of arched design is probably not suitable.

So, if you go by the cost, the cheapest would be three section pratt truss (or variation of thereof) steel bridge.

If you account for the maintenance, than two section (one center pylon) pre-stressed concrete balanced cantilever design would suit you perfectly (aesthetics).

[1pLUs44]

Thought this might be fun for some of you who like this kind of thing and for those who despise engineers to play engineer!

I am going to design a bridge (grad school project) out of either steel or prestressed concrete, and this is the proposed location for where the bridge is going to go.  Cost effectiveness plays a big part.  For example, when the piers get larger cost of them increases non linearly, however not as much cut will have to be made into existing terrain.  Or on another token, the more piers you have, the smaller your girders will be however there will be additional cost for the added pier(s).  Don't worry about this stuff when making a conceptual design.  Lets just say it will be a 2 lane bridge.
Another thing to keep in mind: When you start exceeding ~35meters your girders start to get a lot more expensive quick.  So dont just try a 150m girder across the bridge and say done.  That won't work

Challenge To You guys: Come up with a conceptual design for your bridge.  Where would you place your piers, girders, and consequentially your cut and fill?  Lets call the bottom of bridge minimum at 187 m.  I have a few ideas of my own.  I will take the best ideas out of pool and run cost analysis on all and see which one will be the least expensive and most efficient.

(Image removed from quote.)
(Image removed from quote.)

To get the ball rolling, here's the simplest design I sketched up rather quickly in paint.  Two span simply supported prestressed conc girders with one pier.  Girders will be huge.  Two piers may be more efficient.  Anyways here's to get the ball rolling.

(Image removed from quote.)
(Image removed from quote.)

Cool! I'm actually doing this in my Principles of Engineering class myself, but it isn't as defined as yours. We use a program called Westpoint Bridge Builder and we enter into a contest to see who can design the cheapest bridge that works.

[grizz441]

If you adjust for scale (height/length) you can quickly figure out that any type of arched design is probably not suitable.

So, if you go by the cost, the cheapest would be three section pratt truss (or variation of thereof) steel bridge.

If you account for the maintenance, than two section (one center pylon) pre-stressed concrete balanced cantilever design would suit you perfectly (aesthetics).

How did you come up with that so fast?  Do you have a spread sheet handy or something?