Fundamental Systems: Isostatic Structures and Deformations

This lecture discusses essential definitions related to fundamental systems in structural mechanics. It begins by defining a fundamental system as an initial structure made isostatic by allowing all freedoms under kinematic conditions without any external imposed loads. The instructor explains the effects of external loads on the system, emphasizing the importance of understanding the associated displacements and forces. The lecture covers the concept of displacement associated with unknowns in the fundamental system, particularly focusing on the variable X. The instructor illustrates how to visualize and redraw the system to better understand the deformations and forces at play. The discussion includes the role of springs in the system and how to calculate displacements when X equals one. The lecture concludes with a detailed explanation of how to approach complex systems by decomposing them into simpler subsystems, ensuring a clear understanding of the internal forces and their contributions to the overall behavior of the structure.