An isostatic frame is a structure where the number of unknown support reactions equals the number of available equilibrium equations. For a 2D structure, these equations are: (Sum of horizontal forces) (Sum of vertical forces) (Sum of moments about a point A) Problem Statement: Consider a portique ABCDcap A cap B cap C cap D Support A: Pin support (Articulated) at Support D: Roller support (Appui simple) at Geometry: Vertical columns ABcap A cap B CDcap C cap D ; Horizontal beam BCcap B cap C Loading: A uniform linear load acting downward on the beam BCcap B cap C 1. Calculate Support Reactions First, we identify the unknowns: at point A, and VDcap V sub cap D at point D. Horizontal Equilibrium: Moment at A: Vertical Equilibrium: 2. Determine Internal Forces We "cut" the structure into three members ( ) to find the Normal force ( ), Shear force ( ), and Bending moment ( Member AB (Column): (Compression). Member BC (Beam): Member CD (Column): (Compression). 3. Visualize with Diagrams
Une structure est dite si le nombre d'équations d'équilibre statique disponibles est suffisant pour déterminer toutes les inconnues de réaction (forces et moments aux appuis). exercice corrige portique isostatique pdf
