This Design Of Reinforced Concrete Curved Beams excel sheet is very useful in designing of curved beams.
Reinforced Concrete Curved beams do have a linear strain relationship. At least they do under circumstances where a straight have a linear strain relationship; i.e. away from supports & point loads. They can be designed for combined flexure & axial load
-Flexure formula only applies to members that are straight as normal strain varies linearly from the neutral axis
-Thus another equation needs to be formulated fora curved beam, i.e., a member that has a curved axis and is subjected to bending