Open Spandrel Arch Bridge with Solid Exterior Arch

[andrewd95]

Hello All,
I'm new to posting to the forums but I have found many helpful recommendations in the past via these forums! So thanks to all in advance for your input!

I am working on a load evaluation of a somewhat unique bridge. A picture is attached as I am not quite sure what this bridge type would be called.
It is almost like an open spandrel arch bridge, except the entire arch is solid, as opposed to consisting of ribs. The deck has two stringers and two floorbeams. The old drawings are attached as well for reference.

I am curious if someone could provide input on how these exterior arches would be checked for capacity? I don't think looking at the exterior arch as a variable depth beam between abutments for flexure would be accurate, but I am stuck as to the best way to analyze the arch?

Any input and/or resources would be greatly appreciated!

 

[jhnblgr]

Break it into 10th sections and analyze it like a column in compression.

 

[BridgeSmith]

Strip away the curved concrete at the ends, and it's basically a concrete T beam superstructure. The only difficult part for me if I was doing the load rating would be defining the end of the span for the exterior beams. The conservative approach would be to ignore the concrete arch portions and assume the span lengths of all the beams to be between the front faces of the abutments. I don't think I'd use anything shorter without modeling it in structural analysis software or a FEM.

More critical than that, though, is determining the area and yield strength of the reinforcing. Are those "1" Bars" square, twisted square, or round? You need to know.

What loading are you evaluating/rating it for?