Edit Element

ProBeam — User Guide

Full structural analysis of any 1D beam using the Direct Stiffness Method (FEM), Euler-Bernoulli beam elements. Handles determinate and indeterminate beams exactly.

Sign Convention

• Downward loads: positive. Upward loads: negative.
• Sagging moment (concave up): positive (+). Hogging: negative (−).
• Reactions shown as ↑ upward or ↓ downward.

Supports

• Pin — Fy (and Fx).
• Roller — Fy only.
• Fixed — Fy + moment M.
• ◉ Hinge — Internal hinge: M=0 at location, rotation discontinuity allowed. Shear transfers normally.

Load Types

• Point Load — Concentrated force. Negative = upward.
• UDL — Uniform. Negative = upward.
• UVL — Zero→peak at end.
• Tri ◁ — Peak at start, zero at end.
• Tri ▷ — Zero at start, peak at end.
• Trapezoid — Linear variation.
• Moment — Applied couple CW or CCW.
• ∠ Inclined — Angled point load. F at angle θ. Decomposed into Fx=F·cosθ and Fy=F·sinθ. Only Fy participates in the beam FEM (vertical bending). Angle: 0°=→, 90°=↓, 180°=←, 270°=↑.

Internal Hinge (FEM)

• At hinge: M = 0, deflection is continuous, slope is discontinuous.
• Implemented by splitting the rotational DOF at hinge node into left/right DOFs.
• Each hinge adds one equation of condition → reduces indeterminacy by 1.
• Shown as pink ◉ on beam. BMD crosses zero at hinge location.

Features

• SFD, BMD, Elastic Curve (Deflection)
• Symbolic Equations V(x), M(x) panel (∫ Eqns button)
• Auto static/indeterminate detection with degree
• Point of Contraflexure (marked on beam & BMD)
• Max Shear / Max Moment / Max Deflection auto-labelled
• Reaction values displayed on beam
• Undo/Redo history (Ctrl+Z / Ctrl+Y)
• Save/Load project as JSON
• Export text report
• Snap control (0.1 / 0.5 / 1m)

Keyboard

• Delete/Backspace — Remove selected
• Escape — Deselect / close panel
• Ctrl+Z — Undo
• Ctrl+Y / Ctrl+Shift+Z — Redo