Beam Reactions and Support Conditions simulation
Two canvas panels. Top panel shows the beam with supports, applied loads, and reaction force arrows. Bottom panel draws the Shear Force Diagram (SFD) and Bending Moment Diagram (BMD) in real time.
4 beam types via tab buttons:
Simply supported (pin + roller) Pin at A gives RAx + RAy. Roller at B gives RBy. 3 reactions, 3 equations, statically determinate. The most common beam in textbooks.
Cantilever (fixed + free) Fixed wall at A gives RAx + RAy + moment MA. Free end at B. All load is carried by the wall. Used in balconies, diving boards, sign posts.
Overhanging (pin + roller with overhang) Pin at A, roller at B at 70% span. Beam extends past B. Load on the overhang creates negative bending at B. Still determinate.
Propped cantilever (fixed + roller) Fixed at A plus roller at B. 4 reactions but only 3 equations: statically indeterminate to degree 1. Needs compatibility (deflection at B = 0) to solve. The code uses the standard beam table formula.
Visual details matching textbook conventions:
The sim loads with a 6-joint Pratt truss carrying a single downward load at the bottom chord. Members are gray (unsolved). Support reactions are labeled at joint A (pin: Ax, Ay) and joint F (roller: Fy). The first thing to notice: pin gives two reactions, roller gives one. Three unknowns, three global equilibrium equations. The reactions solve before any member analysis begins.
Pin support: triangle with ground hatch and center pin dot (blue)
Roller support: triangle on two small circles with ground line (teal)
Fixed support: wall with diagonal hatch lines (purple)
Reaction arrows: green dashed arrows with force labels
Moment reaction: curved purple dashed arrow with MA value
DOF legend: bottom left shows what each support provides
Determinacy check: top right shows "3 reactions, 3 eqns: Determinate" or "Indeterminate (degree 1)"