# want to build a plate girder bridge...



## Biblegrove RR (Jan 4, 2008)

I am needing to build a curved plate girder bridge supported by concrete pillars about 4' above ground. Wanting to use PVC boards for the sides etc. My question is... What size or how high should the sides be?


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## Biblegrove RR (Jan 4, 2008)

sorry... 1:29 scale or so.... Also, what can be used/glued to the sides ti imitate the riveted vertical ribs?


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## SteveC (Jan 2, 2008)

It may be a might bit more than you wanted, but it's a good reference.

The Practical Design Of Plate Girder Bridges[/b]


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## Ron Hill (Sep 25, 2008)

John, you might want to look at Kalmbach Books "Model Railroad Bridges and Trestles" I used it to construct both a Double track Through Truss and a Double track Plate Girder bridge. I constructed them out of styrene from Plastruct. The first picture you showed is a box girder bridge.


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## Biblegrove RR (Jan 4, 2008)

Anyone have one from Garden Metal Models they can give me a hiegth measurement from?


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## livesteam53 (Jan 4, 2008)

John 
When I build them I use 3" plus the 1/4" flat bar so the total height is 3 1/2" tall


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## Biblegrove RR (Jan 4, 2008)

thanks Mark, got any pictures to share?


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## livesteam53 (Jan 4, 2008)

http://1stclass.mylargescale.com/livesteam53/IM000266.jpg


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## Biblegrove RR (Jan 4, 2008)

Awesome Mark! Can you give me the width as well? Did you make your own ties on top, they look great!


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## livesteam53 (Jan 4, 2008)

The width is 4 1/2" . Yes I installed wood ties and hand nailed the rail on this one. Total width with ties is 6". 
However if you are just wanting to put track on top make it 3" wide.


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## Ron Hill (Sep 25, 2008)

John, according to the Bridge and Trestle book, a box girder dimension is 7'-9" for the girder depth and 6'-6" for the centerline from one girder to the other. 
Ron


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## livesteam53 (Jan 4, 2008)

For the sizes above 
6'6" 7'9" 
1:24 scale 2 11/16" 3 3/16" 
1:29 scale 3 1/4" 3 7/8" 

I never build exact to scale. I use simple measurements and have fun. Most people think it's right as long as it's close.


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## John J (Dec 29, 2007)

Were Curved gurder bridges comon? I thought they were a series of angled strait sections. I really like the looks of Mark's curved section. I like the support towers. They look great


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## livesteam53 (Jan 4, 2008)

John, 
You are correct I believe a curved bridge was a series of strait bridges. I could never find any bridge that was curved but I made one.


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## pinewoods (Jan 20, 2009)

Girder depth varied considerably and is based on the load and the span. Some bridges used girders of varying depth when the supports were placed at different spacings. Curved girders are generally not practical because as the load moves to the center of the span it would cause the girder to rotate outward and fail. The shoes at the ends of the span have to be outside the center of mass of the of the train to remain stable. 

I too like the looks of the curved bridge but my engineer training says...'that won't work'...Fortunately material strengths scale in our favor and we get get away with designs that look good. 

I'll definitely keep a local copy of that book, nice resource.


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## Biblegrove RR (Jan 4, 2008)

Hey Mark, shouldn't the 1:24 scale be the larger size? am I confused here?


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## RRwannabe (Jan 20, 2009)

HERE is a girder plate bridge I always liked, and a good shot too. its a short-line outfit in NC, the WSSB. 

HERE is another.


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## Biblegrove RR (Jan 4, 2008)

I do not have permission to access that server


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## RRwannabe (Jan 20, 2009)

works for me







maybe try to copy and paste

http://i.pbase.com/g3/10/482310/2/55300366.whitney.jpg

http://i.pbase.com/g3/10/482310/2/55413925.whitney.jpg


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## livesteam53 (Jan 4, 2008)

Oops your right I got the numbers turned around.

Here is nailing the lumber in which I glued and pin nailed 










Starbucks stirring sticks always work for me. The hardest part was keep the curve right.


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## John J (Dec 29, 2007)

What did you use to make the cross bracing in the first picture under the load of ties.


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## livesteam53 (Jan 4, 2008)

1/8" sq steel. 
JJ call me or email you phone number. 
Advise is free!


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## Biblegrove RR (Jan 4, 2008)

I am trying PVC










need to make a curved one but this stuff is too stiff I think - how would I keep the bend?


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## Manco (Jan 5, 2009)

You could try ripping it in half to take away some of the stiffness.


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## Daniel Peck (Mar 31, 2009)

http://s615.photobucket.com/albums/...shed bridge/?action=view&current=HPIM1828.jpg 
I used 2" steel channel bent on a radius. 


Just and Ideal...


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## armorsmith (Jun 1, 2008)

Bible, 

With the PVC you can use two possible methods. First, purchase thinner material and use multiple thicknesses glued together using a form of the correct radius (two required, one for the inner girder and one for the outer). Allow the glue to set completely (a couple of days) before removing the clamps. 

The second is to heat the PVC until it becomes more pliable. Again bend around forms and clamp until cool. 

I prefer the first method (although I prefer wood approximately 1/8-3/16 thick) because there is very little 'spring back' when you release the clamps. The other advantage of thinner material is it is easier to handle when working into the forms, and I don't burn my fingers on the heated material. 

Good luck, 

Bob C.


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## Biblegrove RR (Jan 4, 2008)

I want to thank all who have supported this thread and want to cap it off with a pic of where it will be installed....









THANKS!


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