Influence of geometry and material parameters variability on the ultimate condition of doubly reinforced concrete beams

Analytical formulations for the study of ultimate curvature capacity of reinforced concrete members are useful in design practice, especially for preliminary definitions of member characteristics in order to achieve a ductile behavior. This work, part of a broader research, analyzes the influence of various parameters on failure mode of doubly reinforced concrete beams. Differently from classical approaches, in this work all possible ultimate configurations are considered. An approach for identification of ulti-mate condition based on failure mode domains are developed analitically. It is shown that variations of reinforcing steel amount and ultimate deformation capacity can strongly affect the failure mode of the section and, consequently, its deformation capacity and ductility.