Truss Master
Professional 2D planar truss analysis with a hybrid engine: a matrix stiffness backend produces the ground-truth solution, while the frontend generates line-by-line Method of Joints and Method of Sections derivations verified against it.
Ground truth first, pedagogy second
Two independent paths converge on the same answer — so every displayed step is guaranteed mathematically correct.
Matrix stiffness backend
Assembles the global stiffness matrix from member geometry and E·A, solves for displacements, and derives member forces and reactions — the authoritative result for determinate and indeterminate trusses alike.
Educational generators
Method of Joints and Method of Sections derivations are generated line-by-line, then every computed value is re-verified against the stiffness backend before it is displayed.
Determinacy auto-check
m + r = 2j is evaluated instantly. Determinate models unlock the full educational derivations; indeterminate ones are automatically routed to the stiffness method with a clear explanation of why.
A drafting table and a solver in one
Interactive grid canvas
Pan and zoom from 0.25× to 4× with snap-to-grid, axis labels and automatic joint naming (A…Z, AA…).
Full modeling toolbox
Joint, member, support and load CRUD. Nodal point loads take a magnitude plus angle, with quick up / down / left / right presets; pin, roller and fixed supports.
Per-member materials & area
Each member carries its own E and A. Presets: Steel 200 GPa, Aluminum 70, Wood 12, Concrete 30 — default area 1000 mm².
Determinacy-aware solvers
The m + r = 2j check runs automatically; indeterminate models auto-route to the stiffness engine, determinate ones get full educational derivations.
Step-by-step generators
Seven step types — determinacy, stability, reactions, zero-force detection, joint analysis, section analysis, verification — with progressive reveal and hints.
Visual verification
Joint FBDs with a sign-convention badge, orange dashed section-cut lines, and member color coding: tension, compression and zero-force.
Seven step types in every solution
Member color coding
Joint FBDs carry a sign-convention badge; section-cut diagrams draw the cutting plane as an orange dashed line.
Reports, history & persistence
Simple triangular truss
Published exactly as the solver regression suite locks it: closeTo(2.88, 0.1) and closeTo(5.77, 0.1).
Model — joints A(0,0) pin · B(100,0) roller · C(50,87) · 10 kN ↓ at C
Solver output — verified
Simple triangular truss · 10 kN apex load
Locked by solver regression tests: closeTo(2.88, 0.1) and closeTo(5.77, 0.1) — the same tolerances the shipped app enforces.
An unloaded joint with 2 non-collinear members → both members carry zero force.
An unloaded joint with 3 members, 2 of which are collinear → the third member is zero.
A load collinear with 2 members at a joint → the third member is zero.
How larger models are solved
Multi-panel Pratt and other classic bridge geometries are degree-1 indeterminate in the app: the m + r = 2j check flags them and the model auto-routes to the stiffness engine, which returns member forces, reactions and u/v displacements for every joint. The Method of Joints and Method of Sections generators cover the determinate models they are designed for.
Draw a truss, get a verified solution — with every step shown
Stiffness-verified member forces, joint-by-joint derivations, section cuts and A4 reports — free in the browser, in English or Spanish.