This lecture covers the nonlinear analysis of structures, focusing on computing the force-displacement response of a truss system with inelastic material properties. The event-to-event principle is used to identify state changes in bars from elastic to plastic, allowing for piecewise linear force-displacement responses. The lecture discusses the step-by-step analysis strategy, including applying displacements, determining yielding parameters, and calculating resisting forces. Various solution algorithms, such as Newton-Raphson, are illustrated with examples. The importance of convergence criteria and modified algorithms is highlighted. References to course materials and assignments are provided for further study.