STRINGERS: straight vs. curved

Hello all…which config has more predictable flex/stiffness characteristics relative to near-rail stringers?

Funny things seem to happen with curved rails with touchy feely tests and it seems as if placing them straight rather than curved may have some bennies…namely ease of installation. Stringer foil shape between the two would also be different adding even more complexity to the analysis.

Thoughts?

Prior to breakage, a thin slab stringer tries to bend/twist away from its straight glue line. So where is strength gained by pre-tensioning a flat stringer, i.e. gluing it in an arc rather than relaxed in a straight line? It seems the strongest simple stringer would be an I-beam structure.