This lecture focuses on the essential role of modeling in structural analysis. The instructor discusses various modeling techniques applicable to the same structure, emphasizing that the analysis type influences the chosen model. The lecture illustrates traditional analysis methods and seismic analysis, highlighting the importance of considering non-load-bearing elements. The instructor presents a real-world example involving a road bridge, detailing aspects such as support types, longitudinal slope, and curvature. The course aims to provide an analytical and intuitive understanding of mechanical behavior in structures, stressing the need for critical evaluation of results based on the adopted model. The instructor also outlines the course structure, which includes a detailed exploration of hyperstatic structures, methods of forces, and displacement methods. The importance of drawing and visualizing forces is emphasized, as it aids in understanding the mechanics involved. The lecture concludes with a discussion on the significance of accurate modeling in engineering practice, particularly in relation to real-world structures and their behavior under various conditions.