Enriched Force-Based Frame Element with Evolutionary Plastic Hinge

This paper presents a novel enriched force-based formulation for beam-column elements. The enrichment was developed on the basis of the concept of evolutionary plastic hinges and incorporated with conventional force-based element formulation. The evolutionary plastic hinge was activated on the basis of the crushing of concrete and/or yielding of reinforcement, whereas its length was calculated adaptively according to real-time sectional forces. Several representative numerical examples are demonstrated, verifying that the proposed model can achieve accurate and objective responses regardless of the number of integration points. The spreading of plasticity in strain-hardening problems and the localization of deformation in strain-softening problems can be captured well by the proposed element.