Seems that most of the textbooks are dealing with elastic beam calculations, where a beam is fixed from both ends and initially there is no axial stress or load applied. My problem is different in a way that an elastic rectangular beam is fixed from both ends and it is under certain tensile load F (given). I know the bending deflection y in the center of the beam due to applied load in transverse direction (that load is not given). The question is how to calculate an increment in axial stress by knowing the deflection y in the center of the beam that is generated by applying a load in transverse direction? Given: Dimension of the beam, L, h, w Elastic modulus (both tensile and bending) Initial axial load, F Deflection in the center, y Any help appreciated.