I am planning on scratch building several HO scale 2 track through plate girder bridges, about 8' of them in 10 to 12 inch sections, several of these will be supporting curved track (15" to 22" radius flex track). Could someone please point me towards some pictures of the structual details. I am planning on using ABS webs and flanges from plastruct for the plate girders. But I am having trouble finding details on the roadbed structual supporting system. Any suggestions in this whole project would be greatly appreciated.
I'm surprized in your searching you didn't come across this - The Practical Design of Plate Girder Bridges (google books) - looks like the entire book is there (since it's 1920, it's out of copyright). Plenty of diagrams in that book, and the bridge construction techniques would apply to bridges built until WWII, and some of those bridges are probably still in use today.Also, if you haven't already, use the Train Magazine index (link set to search for Girder), see if you have any of those issues (Sorry, looks like TrainLife can't help you on this).
This might help too, not sure if you've seen it already.Plate Girder Bridges are very popular subjects...
Here's the real deal on the prototype:
With radii that tight, you might want to re-think using through-type girder bridges, as side clearances may be too tight. Where vertical clearances allow, a deck girder bridge of similar span will do the job with no side clearance problems.
Our prototype friends prefer to use deck bridges, going to through girders only where needed to provide under-track clearance over roads, navigable (or flood prone) channels or other tracks. One reason is that the floor structure is a LOT simpler.
IIRC, a half-century or so ago Model Railroader ran a series on bridge design as part of a wider series of prototype information for modelers. Somebody with a better memory (or the MRR DVDs) can probably provide a reference. The author (Paul Mallory?) noted that the floor structure for through bridges was the same regardless of whether they were through girders, through trusses or cantilever spans.
Chuck (Modeling Central Japan in September, 1964)
Model Railroader magazine