Report availability of the built-in solver, CalculiX (ccx) and FreeCAD (freecadcmd) on this machine.

Create a new empty structural model. Use add_nodes/add_material/add_section/add_members/add_supports/add_loads to build it, or use generate_structure for common typologies.

List parametric structure generators (bridge and building typologies) with their default parameters.

Create a complete model (geometry, sections, supports, loads) from a parametric typology preset: beam_bridge, truss_bridge (pratt/howe/warren), arch_bridge, cable_stayed_bridge, portal_frame, moment_frame_building, braced_frame_building, roof_truss. Params override preset defaults (see list_structure_presets).

Add nodes to a model. Coordinates in meters, global +Z up. Node ids are optional (auto-assigned integers).

Add a material. E = Young's modulus [Pa], nu = Poisson ratio, density [kg/m3] (needed for self-weight), fy = yield/design strength [Pa] (needed for utilization checks). Example steel: E=210e9, nu=0.3, density=7850, fy=355e6.

Add a cross-section. Shapes and required params [m]: rectangle{b,h}, box{b,h,t}, pipe{d,t}, circle{d}, isection{b,h,tf,tw}, generic{A,Iy,Iz,J[,cy,cz]}. Convention: b = width (local y), h = depth (local z); for horizontal members local z is vertical, so Iy is the strong axis for gravity bending. Valid shapes: rectangle, box, pipe, circle, isection, generic.

Add beam or truss members between existing nodes. type "beam" (default, 6 DOF frame element) or "truss" (axial only, for braces/cables/truss webs). rollDeg rotates the section about the member axis.

Add supports at nodes. type is one of fixed, pinned, roller, roller-yz, planar-xz, or a 6-character 0/1 string for (ux,uy,uz,rx,ry,rz), e.g. "111100". "roller-yz" is a typical bridge sliding bearing; "planar-xz" restrains out-of-plane DOFs for 2D models in the XZ plane.

Add nodal loads [N, N·m], member uniformly distributed loads [N/m], and/or set the self-weight factor (1 = full gravity). Downward = negative fz/wz. UDL sys "global" (default) or "local" (member axes).

Run linear-static analysis. engine "beam" = built-in 3D direct-stiffness solver (fast, exact for Euler-Bernoulli frames); "calculix" = CalculiX FEM (B32R beam elements); "both" = run both and compare max displacements. Returns displacements, reactions, member force envelopes, stresses and utilization (stress/fy).

Retrieve detailed results from the last analysis: "displacements" (per node), "reactions" (per support), or "member_forces" (end forces + envelopes per member). Optionally filter by ids.

Build a solid 3D representation of the model (member solids + support markers) and save it as a FreeCAD .FCStd document you can open in FreeCAD. Runs headless freecadcmd; takes ~5-20 s.

Write the CalculiX .inp input deck for the model (B32R beam elements) without running the solver.

Summary of a model: counts, materials, sections, loads, bounding box.

List all models in this session.

Delete a model from the session.