Analysis of Reinforced Concrete Beam‐Columns under Uniaxial Excitation

Abstract

Finite‐element models of reinforced‐concrete beam‐columns often fail to behave in a stable manner near the point of maximum resistance. Simple numerical examples presented indicate that the conventional displacement formulation when used at the section or member level is unable to establish solutions associated with softening behavior. Thus, such analysis models are often limited in their applicability or necessitate the use of unrealistic material laws. A mixed finite‐element scheme is proposed herein that exhibits stable numerical behavior even when critical regions become ill‐conditioned. It is demonstrated that enforcing equilibrium within the member during state determination provides the necessary constraint to obtain a stable solution. Examples are presented to demonstrate the reliability and realism of this approach for members subjected to generalized excitations even where severe deformation softening occurs.