In a recent publication (Vest et al., 1989), the authors presented the equivalent beam stiffness method, a direct procedure of determining the effective bending stiffness profile for beam-like structures using measured modal data and assumed correct mass and transverse inertia distributions. This paper details the further development of the method, in preparation for its application to ... [Show full abstract] experimental data obtained from large scale turbine rotors. By using a consistent polynomial basis for all quantities during the required integration and differentation, the improved accuracy of the method is demonstrated, as well as the ability for it to extract accurate profiles from computed modal results for complex stepped shaft designs. The effects of input noise are examined, and it is shown that the integrity of the method is not severely diminished even in the presence of noise levels above that to be expected in the experimental work to follow. Topics such as measurement point density requirements and the importance of the initial mode shape interpolation are discussed, as well as the relationship to other techniques available today.