TrussCraft

Overview

TrussCraft designs timber roof trusses in BimCraft, PartCraft, ModelCraft and CadCraft: for a roof read from a BimCraft model, or an outline you type or take from a sketch, a face or a closed polyline. It reads the roof's own geometry and lays out the common trusses together with the sets the roof needs: hip ends framed with step-down trusses, or with a girder truss that carries jack and corner trusses, and valley sets that carry a lower wing roof on a main roof. For every truss it makes the members, the cut list and a joint schedule, finds the member forces by the method of joints for the pressures and combinations YOU enter (dead, snow or live, wind, uplift), checks axial force and chord bending between panel points, estimates deflection, lists bearings and a bracing checklist, and can write every member into the model as an IfcMember in one undo step. A truss that cannot be made is reported as a Problem, never skipped. It is a first check and a drafting aid, not engineered truss design or a manufacturer's sign-off.

Who it’s for

• Architects and designers who want a roof truss layout and a member list before the engineer or the truss maker is involved.
• Builders and estimators who need a cut list and a count of trusses for a roof.
• Students learning how a truss carries load: the forces in each member are shown, with the method used.
• Pre-fab shops and carpenters who want a cut list, a stock-length plan and a life-size jig drawing of a truss (PartCraft, ModelCraft, CadCraft and BimCraft all offer them).

What you can do

• Design one truss of eight types (king post, queen post, Howe, Pratt, Fink, scissor, mono, attic) from span, pitch, overhang, heel height and spacing.
• Lay out a roof read from the model, or typed corners, as common trusses plus hip step-down trusses, a hip girder with its jack and corner trusses, and a valley set over a main roof; sections that cross a valley are made with the valley as a joint.
• Model a raised heel with a real bearing stub member, in the member list, the cut list and the placed geometry.
• Enter dead, snow or live, wind and uplift pressures (kPa or psf) and your own combination factors; find member forces for each combination, with uplift reversing the forces, and see the governing combination per member.
• Check chord bending between panel points when you give an Fb, estimate deflection from the species table's E, and list bearing reactions, uplift and a bracing checklist as Problems.
• Treat the attic truss's room as a frame with rigid corners (a stated idealisation), so it solves instead of reporting a mechanism.
• Load your own connector plate table and species table (CSV or JSON); until then plates are labelled "Placeholder, not a manufacturer value".
• Get the member list, the whole-set cut list and the joint schedule as CSV files; draw the elevation of any design in the set and a 3D view you can turn.
• Read the not-a-design notice and the typical-values notice in Problems, every time.
• In BimCraft, write the members into the model as IfcMember with their sections, in one undo step.
• In PartCraft, place the set as timber-coloured display bodies in the viewport (one undo step per group), taking the roof outline from a selected sketch.
• In ModelCraft, place one mesh object per truss in a group, painted in the species colour, taking the outline from a selected face; ModelCraft's own export then writes STL, OBJ or glTF.
• In CadCraft, draw the layout plan, a truss elevation, the member force diagram and the cut and joint schedule as real lines, polylines, text, hatches and dimensions on TRUSS-* layers, taking the outline from a selected closed polyline; save as DXF or DWG as for any drawing.
• Nest the cut pieces onto the stock lengths you list (one run per sawn size) and draw one truss as a jig layout at 1:1, with member outlines, plate rectangles and cut angles.
• Export the whole set as STL or OBJ.

Methods and standards

Roof profiles are cut from BimCraft's roof geometry along the plane each truss stands in, so every truss top chord is the roof. The method of joints for a pin-jointed plane truss; every distinct design is solved for the dead, snow, wind and uplift cases and combined with the factors you enter. A girder takes the end reactions of the jack trusses it carries as point loads, case by case. Chord bending uses a simple span (a divisor you can change) with the published tension-plus-bending and compression-plus-bending interaction equations, run only when you give an Fb. Deflection is by virtual work from the species table's E. The attic room is solved by the direct stiffness method with the corner fixity you state. Cut lengths are long point to long point along the centre-line.

Data and sources

A species and grade table, the sawn sizes and a dead-load starting set, all labelled typical values and rounded; they are not a standard's tables. Wind, uplift, combination factors, Fb, Fc-perp and the deflection limit start blank or zero: you type the values of the standard in force. The connector plate series is a labelled placeholder (area times a stated constant) until you load your own table.

Verification

The add-on's own test run covers all eight truss types, the profile trusses for every form (member and joint counts), forces against hand-worked figures (king post; a monoslope jack; wind on a king post; uplift), bending and deflection worked by hand, the hip step-down heights, the girder and jack set with the girder's point loads equal to its jacks' reactions, the valley set heights and spans on a typed wing and on a T-shaped roof, plate and species table loading, the bearing stub, the attic as a rigid frame (the frame solver checked against beam theory), the Problems for what cannot be made, and a real web-ifc model in which the saved IFC holds the members and undo removes them. A headless Chrome run on the showcase house is in the session log. Nobody has checked it against a truss designer's software or an engineer's calculation yet.

Limits

Not a substitute for engineered truss design or manufacturer sign-off. Not built: unbalanced snow, drift and concentrated loads other than the girder's jacks; the reactions of valley trusses are listed but not added to the main trusses; the girder or wall along a valley set's wing mouth; hip end stations lower than the smallest truss height (framed by hand); joint slip and net section at plates; plate capacities beyond the table you load; bracing design; scissor trusses with crossed bottom chords. The attic result depends on the rigid corners you state. The words are English, with a draft Spanish (Mexico) file. Per app: PartCraft's bodies are display bodies (no boolean, mass, STEP or picking); ModelCraft's trusses are mesh objects, not faces; CadCraft's drawings are plain entities that do not follow the design when edited, and nothing is drawn in 3D; PartCraft, ModelCraft and CadCraft have no roof model to read, so hips and valleys come from the straight skeleton of the outline you give at one pitch. SuperCad Studio has no add-on host of its own: TrussCraft arrives with its mounted apps, and in the mounted CadCraft is used from the command line.

Files and formats

BimCraft: IfcMember elements in the IFC. PartCraft: display bodies kept in the part file. ModelCraft: mesh objects in the model. CadCraft: entities in the drawing (DXF, DWG). Everywhere: member, cut, joint, layout and stock lists as CSV, the elevation and the jig drawing as SVG, the set as STL or OBJ.

Get started

1. Add TrussCraft and switch it on in Settings > Add-ons of the app you work in.
2. Open the Trusses tab. Under Loads and combinations, type your own pressures and factors (they start at zero).
3. Give the roof: choose one in the BimCraft model, or type the outline, or press Take outline from the selection.
4. Press Lay out on the roof, read the Problems, load your plate table if you have one, then press the place button (or one of the app's drawing buttons).

Languages

The text is available in:

• Afrikaans (af)
• Amharic (am)
• Arabic (ar)
• Azerbaijani (az)
• Belarusian (be)
• Bulgarian (bg)
• Bengali (bn)
• Bosnian (bs)
• Catalan (ca)
• Czech (cs)
• Danish (da)
• German (de)
• Dhivehi (dv)
• Greek (el)
• English (en)
• Spanish (Spain) (es-ES)
• Spanish (Mexico) (es-MX)
• Estonian (et)
• Persian (fa)
• Finnish (fi)
• Filipino (fil)
• French (fr)
• Galician (gl)
• Guarani (gn)
• Hebrew (he)
• Hindi (hi)
• Croatian (hr)
• Hungarian (hu)
• Armenian (hy)
• Indonesian (id)
• Icelandic (is)
• Italian (it)
• Japanese (ja)
• Georgian (ka)
• Kazakh (kk)
• Khmer (km)
• Korean (ko)
• Kyrgyz (ky)
• Lao (lo)
• Lithuanian (lt)

Works in

Comes with

Nothing else.

Permissions

• Adds commands
• Adds a panel section
• Opens or saves its own file types
• Keeps its own settings in this browser

From its manifest. Shown again when an update changes them, and the update waits for your yes.

Versions

Licence and maker

CadCraft (CadCraft, first-party). Licence: Apache-2.0. Dependencies carry their own licences, listed on their pages.