I was just thinking the other day about how the rebar tool and the arch workbench are really well-suited for reinforced concrete design. More specifically, in my line of work, we often do custom rebar layouts for bridge decks and cast in place drainage structures (box culverts that pass underneath roads, manholes, and other junction-type structures).
Below is a link to a PDF of a standard box culvert design we use at the Illinois Department of Transportation (IDOT). It's a nice example of an industry-standard design document that FreeCAD is, in my opinion, capable of with a little extra effort... maybe.

http://www.idot.illinois.gov/Assets/upl ... tails.pdf
In any case, I don't know that it's worth pursuing at the moment - I'm trying to sort out how one could use these tools to do custom structure design in the transportation engineering sector. Still, I don't see much in the PDF plan sheets that FreeCAD couldn't reasonably produce if someone put their mind to generating the python code for it. The question is, how useful would it be to others outside my use case?
If there's any low-hanging fruit in this, it might be the ability to generate a rebar schedule (I don't see evidence this functionality exists yet). Essentially, it calls out each bar's name (usually designated by one or two characters like "h", "s1", "v", etc.), the number of bars that occur in the design, the bar size, the bar length, and a depiction of it's shape. There's also a tally of the structure's volume, the total weight of the rebar steel, the number of splicers required to join the rebar, and the square footage of permanent sheet piling (steel barriers used to retain earth while the hole is dug and the culvert is constructed). Some of that is determined by formulas or quantities that are a part of the design.
Anyway, see page 4 of the PDF link for details on the schedule of quantities.
Apart from that, I was wondering, has there been thought given to using FEM to analyze reinforced concrete structures?
Just for the sake of completeness, this ties into the Civil Engineering Workbench / Transportation Engineering discussions:
Civil Engineering Workbewnch wiki:
https://www.freecadweb.org/wiki/Civil_E ... rkbench/en
Transportation Engineering topic:
https://forum.freecadweb.org/viewtopic. ... &start=330
General Civil Engineering topic:
https://forum.freecadweb.org/viewtopic. ... &start=170