Lecture
This lecture introduces beam-column elements, focusing on displacement-based and force-based fiber beam-to-column formulations. It covers the limitations of concentrated plasticity models, member instabilities, and local responses. The material nonlinearity in beam-column elements is explained through stress-strain constitutive laws. The lecture also discusses nonlinear model fidelities, section level analysis, and the state determination of fiber sections. Nonlinear geometric transformations, including element deformations and consistent definitions of axial deformation, are explored in detail.