Central Valley bridge kit modification

[rrebell]

So I ended up getting some brass stock 1/4"x1/16", a little short in length but I was going to block there as it will be hidden in brush.

[wp8thsub]

rrebell

I noticed you let the splices fall where they may, I am at that point and wondered if I wanted to do that or be more even.

Search some prototype photos for ideas.  The prototype for Central Valley's kit is a former SP bridge over Piru Creek in California http://bridgehunter.com/ca/ventura/bh42629/ .  Bridgehunter has lots of photos of pin-connected trusses http://bridgehunter.com/category/tag/pin-connected/ .

Back when I built mine, I just followed the kit instructions and let the splices end up wherever they did.  

[rrebell]

wp8thsub

I built the above bridge using the Central Valley kit.  I assembled it without leaving provision for the truss to be removed, making it more than strong enough not to deflect.  Note that other truss bridges, like the Walthers kit, lack the metal reinforcement and they hold up just fine (they also tend to be designed with the intention the whole structure will provide strength, so the truss and deck portions are not separable).

 

Thanks for the pic, as that is exactly what I am building! I noticed you let the splices fall where they may, I am at that point and wondered if I wanted to do that or be more even.

[wp8thsub]

I built the above bridge using the Central Valley kit.  I assembled it without leaving provision for the truss to be removed, making it more than strong enough not to deflect.  Note that other truss bridges, like the Walthers kit, lack the metal reinforcement and they hold up just fine (they also tend to be designed with the intention the whole structure will provide strength, so the truss and deck portions are not separable).

[bogp40]

Although you should really have the metal stiffening plates, now that the bridge is much shorter, if you fasten the upper girder (superstructure) of the bridge, it should be strong enough and stop any deflection. The upper truss is designed to be "lift off' one of the reasons for the metal reinforcment.

[MisterBeasley]

I have one of their truss bridges.  (Nice choice of model, by the way, whichever one you've got.)  On this bridge, it's the deck that gives the structure its strength.  The superstructure is purely decorative.

I'd go to the hardware store and get some brass strip that will fit in the space available, or even some square box tube.  Brass is easier to work than the strips provided with the kit.  It's softer, too, but with the torsional stress edge-on, that should not be a problem.

[rrebell]

Because I had to add a piece of styrene to the inside of the girder, the metal would have to be shorter in highth by 1/8" aprox. Could add more styrene through the slots.

[farrellaa]

I would definately cut the metal strips to fit, that is what gives it it's strength/ridgity.

   -Bob

[maxman]

Coud you not cut the strips?

[rrebell]

I shortened the bridge by two sections and because of other modifications, wasn't able to use the metal stiffener strips. Do you think it will still work without deflecting too much, the accual span will be closer to 3 sections (the origingal being 6 sections).