Recommended test
Run a Manual W-frame check and confirm that result display controls do not change the geometry.
- Choose a supported W-frame in Truss Builder, keep Manual mode and expand Truss analysis.
- Review snow, roof and ceiling loads and CC, then select Check truss.
- Compare load cases and change the deformation display scale; confirm the physical truss remains unchanged.
- Download the report, change a load and confirm the previous result becomes outdated.
Analysis and sizing are separate
Truss analysis checks an existing supported Manual W-frame without changing its sections. Automatic member sizing uses solver results in a catalogue search and applies a complete passing preliminary result. A full Mansard roof has a third workflow: a separate read-only 3D assembly experiment.
Code_Aster computes the response of the analytical model and loads supplied by Autostrek. It is separate from the CAD/Open Cascade geometry engine. Displaying a solid model or connector plate does not establish its structural capacity.
Select an available Cloud service or pair the Windows local calculation engine. A service-unavailable message means no result was obtained, not that the truss passed or failed. Hosted calculations require no local installation; the optional Windows alpha runs the same solver on your computer.
Check a Manual W-frame
In Truss Builder, choose W-Frame, keep Manual member sizing and expand Truss analysis. A compatible selected truss can also be checked from Build.
Enter characteristic ground snow load in kN/m², not a snow-zone number. Review roof dead load per sloping area and ceiling dead load per horizontal area. Timber self-weight is added automatically. Building checks use the building’s CC; standalone checks expose an editable CC. When an existing total roof weight already includes the ceiling, do not count the ceiling again.
Select Check truss. The current read-only W-frame scope is the supported four-web layout, with a span of 2–12 m, pitch of 10–40°, overhang of 0–600 mm and CC of 200–1200 mm. These are software input bounds, not approved span limits. Unsupported edited, dormer, porch or upper-storey contexts need another model.
Understand the display
The result shows dead load, balanced snow and snow on either side. It reports sampled elastic vertical displacement, support reactions and member forces/stresses.
- Stress colours rank members within the current result. Orange is not a capacity-failure colour, and blue is not a safety approval.
- The dashed deformation diagram exaggerates movement. Its scale slider changes the drawing only.
- Reactions describe loads transferred to the declared supports. They do not verify the supporting wall, floor or foundation.
Open Assumptions and forces for the calculation details. Download report preserves the request, results, method, solver identification and limitations. Input changes invalidate the result; a read-only report is not a permanent approval embedded in the project.
What is outside this check
The W-frame analysis is a planar elastic model. Its out-of-plane constraints do not verify real bracing. The read-only result does not itself check complete strength, stability, connections, creep, fire, wind or Norwegian design combinations.
Automatic sizing adds scoped preliminary member and serviceability checks. Its accepted results still require connection, bracing and full design verification. Full Mansard analysis uses a separate spatial model and must not be replaced with a single planar-truss result.