Section Method for Internal Forces and Moments

This lecture covers the section method for calculating internal forces and moments in beams, focusing on axial force, shear force, and bending moment. The instructor explains the importance of conventions and sign conventions in determining the direction of internal forces. The lecture demonstrates the step-by-step process of applying the section method, including drawing force diagrams, calculating reactions, isolating subsystems, and achieving equilibrium. Emphasis is placed on understanding edge conditions, control points, and where to make cuts in beams to analyze internal stresses. Practical examples and a systematic approach are used to illustrate the concepts.