I’m building a bridge and I wonder how thick styrene sheet I should use for the sides in HO scale, any suggestions? I think the sides are called web plate or girder but I can be wrong about that.
It depends. Mainly because no one will be able to tell how thick it is. In real life netween 1/4" and 1/2". Beam mechanics are predicated upon the two horizintal members being in tension and compression top to bottom respectively. The web is merely a device to keep them alligned. High rise buildings became a lot easier to contruct when engineers figured out that by widening and thickening the horizontal members while increasing the distance between them they could hold a lot more weight. hence we have wide flange beams today. Now that the history lesson is over if the bridge is going really be a bridge and support the weight of the trains I would use some fairly thick styrene like 1/8". If the roadbed is going to support the track and the bridge is cosmetic then I would use something thinner that is easier to work with. In either case thin stock with rivet lines will be the clincher for realism.
Thats what you get for typing before you are completely awake. The top one is in compression and the bottom in tension.
The bridge is only cosmetic so I think I don’t need a thick styrene sheet. I was thinging maybe 1-2 mm thick.
EL…
For scratchbuilding, I like .040" (1mm) thick styrene sheet. Though it’s an unrealistic 4 scale inches thick, it’s structurally rigid and doesn’t need a lot of bracing. For your bridge project, use .040" thick sheet for the plate girder with 5/64" angles (available from Plastruct) for the stiffener angles at the plate joints and .020" (.5mm) strip for the cover plates.
Get this book for valuable reference matierial: ‘Model Railroad Bridges & Trestles’, published by Kalmbach (subtitled ‘Model Railroad Handbook No. 33’). Chapter 2 provides a good overview of the design and structure of plate girder bridges.
Hope this helps.
Bruce J.
Electro:
If I were you, I’d kitbash the girders from a couple Central Valley girder kits or a couple Atlas girder kits. You can use a little bit of cutting and filing to square off the ends of the girders.
Trying to make and place all those little rivet strips yourself is going to be a major pain (ask me how I know) … not something I would want to tackle when you can get a perfectly good example in kit form already done for you.
That's one of the keys to building a *big* layout ... learn how to cut corners every place you can. If you can kitbash something that's darn close, don't scratch build it. Scratchbuilding takes a lot of time and you'll never get a large layout built if you take that approach on everything.[swg]