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Author Topic: Is this a kind of bridge ??  (Read 2209 times)

Jardine

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Is this a kind of bridge ??
« on: March 06, 2016, 05:52:17 PM »

Picture a cable stayed span, but with only one pair of cables from each tower, and tying the deck 1/3 of the way out from each tower, and the three segments of that span are long trusses or beam spans.

Be thinking if beam spans then in the range of 4-500 feet each, and if truss, then 7-800 feet each.

From abutment where cables tie back, would be complementary spans to the towers.  Overall length would be 2000 to 2500' for the beam bridge (with only 2 piers/towers) or 3500' to 4000' for the truss version, and again, with only 2 piers/towers.

Kind of a marriage of the cable stayed and the cantilever varieties.


Anyone know of anything built along those lines ?
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Jardine

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Re: Is this a kind of bridge ??
« Reply #1 on: March 08, 2016, 01:01:37 PM »

Found one !!

Towers are a bit over wrought, but that's the idea there.

All in all, nice looking bridge.


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davewiecking

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Re: Is this a kind of bridge ??
« Reply #2 on: March 09, 2016, 09:37:33 AM »

I like this design, and especially the "lightweight" portions between the cable attachments. I don't immediately recognize the skyline, nor any of the folks in the boat. Where is this?
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empirestate

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Re: Is this a kind of bridge ??
« Reply #3 on: March 09, 2016, 09:45:13 AM »

Wait, did you randomly have this idea for a bridge in your head and then happen to stumble across a photo of one in real life? Or had you seen the actual bridge some time before and just weren't sure where to find it?


iPhone
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Jardine

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Re: Is this a kind of bridge ??
« Reply #4 on: March 09, 2016, 01:01:24 PM »

Both.

When I was a kid I tried making cable stayed bridges with Kenner girder and panel building sets.  The compression in the span between the tower and the cable attachment always distorted the framing and I never was able to make one that looked or hung correctly.  Probably should have asked for an Erector Set at Christmas instead.


I think I saw a 2 second glimpse of the Venezuelan bridge pictured above several years ago on a news report on either the Millau Viaduct or maybe it was the Oresund or maybe that odd suspension bridge in England with the inclined hanger cables.  Didn't think about the wonky Kenner set attempts until I found a couple of red plastic girders when cleaning a box of crud out of the attic a while back.

I made quite a few suspension bridges with the Kenner stuff, but I was terrible at making stable anchorages on the slick hardwood floor in the play room, and once a Kenner set suspension bridge is longer than 18" or so, little kids just don't have the skill set (read that as patience) to tweak the model and get everything just so.  Especially when I was trying to make a double deck span like the Verrazano Narrows Bridge, LOL !!

I didn't have enough Legos to make rigid towers either . . . . .
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Jardine

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Re: Is this a kind of bridge ??
« Reply #5 on: March 09, 2016, 01:15:57 PM »

I BEGGED for an HO scale train to combine with the Kenner stuff, and my parents bought Lionel instead.  I never was able to crossover those two toys.

The Lincoln Logs were similarly limited . . .
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jakeroot

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Re: Is this a kind of bridge ??
« Reply #6 on: March 09, 2016, 01:36:08 PM »

Your description reminds me of the Kiona Bridge west of Richland, WA:


[Source]
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Jardine

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Re: Is this a kind of bridge ??
« Reply #7 on: March 09, 2016, 01:54:17 PM »

Wow, love that one.

The simplicity of the towers works so much better for the form than the Venezuelan one.

Also, concrete from the towers to the suspension point for resistance to the compression forces, and steel for the center span for the (assumed) tension forces.

I'd almost think if the design put enough tension in the center span, a uniform deck* all the way from tower to tower would be possible, and look 'svelte'.



*and maybe a hinge or something at the suspension points, there being all kinds of forces converging at that line across the deck.

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Jardine

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Re: Is this a kind of bridge ??
« Reply #8 on: March 09, 2016, 01:56:20 PM »

That lengthened overpass pictured on here a while back is a sad sad example too, sort of, with that wonky center pier, that thing is really an abomination.
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