ABSTRACT
Moment-rotation relationships of RC beams provide an estimate of the beams’ ductility, which is a valuable design parameter. The correct estimate of ductility is very important in the context of recent advancements in design approaches like displacement-based design. In this chapter, collapse mechanism and plastic hinge extensions of RC beams in bending, under increasing concentrated design load until collapse, are examined. Moment-rotation relationships in explicit form, in elastic and elastic-plastic ranges, are derived from the proposed bilinear modeling of momentcurvature relationships, presented in Chapter 2. Analytical estimates are verified for equilibrium and compatibility conditions. Ductility ratios of two cases, (1) a fixed beam and (2) a simply supported beam, are presented. The proposed analytical procedure is capable of modeling the moment-rotation relationship, accounting for nonlinear characteristics of the materials, and providing a satisfactory estimate of ductility. They are useful for designing special moment-resisting RC framed structures, in particular, where ductility is an important design parameter. In the technical context in this chapter, relative rotation occurring between the extremities of a plastic hinge is termed as rotation.
