Abstract: For the elastic supported continuous beam and frame, its internal forcesare related not only to the stiffness of each member, but alsoto the stiffness of the supported structure. With a different tensionand compression modulus, the flexural rigidity of each member is notconstant any more (as is different from that of classic mechanics), but isa function of the internal force, that is, the calculation for the internal forceis a nonlinear problem. In this paper, the formulas of neutral axis andinternal force for the elastic supported continuous beam and frame arederived by using the phased integration method, and an iterative programfor nonlinear internal force is developed, an example is calculated andanalyzed. In the end, the author proposes asuggestion for the calculation of structure, and concludes that thestructure can be optimized by using the different modulus theory.