Basic design requirements of the load-bearing structure. Types and identification of actions. Classification of carriers according to their mechanical behaviour. Comparative presentation of the main categories of linear members (beam on post, frames, arches, cables) in terms of their ability to bridge openings and to receive vertical and horizontal actions. Approximate solution and pre-dimensionalization of isostatic and hyperstatic linear bodies by simple methods. Alternative technical solutions for the bridging of openings (solid or lattice girder, single or multiple openings, with direct or indirect supports), for columns (vertical, oblique, V or tree-type), walls and stiffening links to ensure stability in the space and the absorption of horizontal actions (earthquake, wind, etc.). Criteria for the selection of carrier type and material, depending on the architectural requirements. In-depth study of the mechanical behaviour of members against various stresses, with emphasis on bending with or without axial force. Stiffness and stiffness of linear load-bearing members and correlation with the optimum cross-sectional shape. Basic principles of layout in plan of vertical load-bearing elements in reinforced concrete structures for good behaviour under seismic actions. Concepts of centre of mass and centre of elastic rotation.