Trusslab: free online 3-D frame and truss analysis

Trusslab is a free 3-D structural analysis workbench that runs entirely in your web browser. Model space frames, grillages, space trusses and pretensioned cable nets with member releases, rigid end offsets and your own section properties, then solve them by linear static, P-Delta, linear buckling or modal analysis.

Load cases and combinations, self weight, thermal loads, support springs and settlements are included. Every run reports its own sanity checks (equilibrium of loads and reactions, automatically held degrees of freedom and a conditioning hint), and the built-in Verify view runs the reference suite on your device.

What Trusslab can do

3-D frame, truss and tension-only cable members with releases, offsets and local axes
Linear static, P-Delta, linear buckling and modal analysis; Newton-Raphson for cables
Load cases, signed combinations, self weight, thermal loads, springs and settlements
Deformed shapes, N, V, T and M diagrams, reactions and animated mode shapes
Per-run sanity checks: equilibrium, held DOFs, convergence and slack cables
Open JSON model files, CSV tables, DXF geometry, SVG/PNG pictures and a print report

How we verify Trusslab

Trusslab is checked against 90 independent reference cases. Where a reference answer exists you can run every check yourself on the Verify page, and the Trusslab user guide documents every feature and limitation.

The solver is checked against closed-form beam, column and vibration theory, section-property integrals, exact file round trips, and models re-solved by a separately written finite-element reference program. The catalogue distinguishes independent derivations from retained same-formula slope-deflection and section checks; those checks also have independent flexibility or energy-integral companion tests. Each case lists what it checks, its reference, citation and applicable tolerance.

Trusslab is part of Open Tools, the free engineering tools that run in your browser.

Professional use. Results are for education and preliminary design. They must be checked by a qualified professional, and they are not a substitute for code-compliant design or licensed engineering judgement.