Joist is a horizontal structural member used in framing to span open spaces. Can be made of wood, engineered wood, or steel. Wood joists typically have plank cross section with vertical faces. Engineered wood joists resemble Roman letter "I". Steel joists can take shapes like "C", "I", "L", and "S"
Rafters are structural members extending from ridge to wall plate supporting roof components. Pair of rafters is called a couple. Modern buildings prefer trussed rafters for cost and ease of construction
Influence lines graph structural function variations under unit loads. Used for beams, trusses, bridges, and other structures with moving loads. Shows maximum load effects for reactions, shear, moment, and deflection
Prestressed concrete is strengthened by compressing concrete during production. High-strength tendons are embedded within or adjacent to concrete. Material combines concrete's strength with steel's ductility
Bending moment is the reaction induced in structural elements under external forces. Beams are the most common structural elements subjected to bending moments. Beams can be simply supported, encastre, cantilever, or have fixed ends
Pure bending occurs when a beam is subjected to constant bending moment without shear force. Simple bending involves only bending moment, no shear force between supports