Design or check a girder's prestressing tendons (Tendon Designer)
tendon_designDesigns the post- or pre-tensioning tendons of a concrete girder in the open model to EN 1992-1-1 with the Tendon Designer plugin's own engine, or reads the model's own tendons and checks them (mode improve, the default when tendons run along the girder). Reads the girder (a structure group, element list or the CIVIL NX selection; for improve it is picked from the tendons), its sections, supports and concrete, and the forces: construction-stage results when the model has stages (stage by stage for improve), else the static load cases named, plus an optional live envelope and ULS envelope combination. The girder is ONE girder line (a group holding several girders is split; girderLine picks one). Composite girders (precast + deck slab) are checked stage by stage (compositeMode) with the slab's own concrete, including the slab top; standard precast beams are pre-tensioned on their published strand positions, with debonded (sleeved) strands set or searched for by debonding, each end's length separately. Then auto-designs the layout (new) or reads the tendons in (improve), and runs every check: stresses at transfer and in service, Magnel, load balancing, losses, ULS bending, cover, spacing, bend radius, anchorage zones. autoResolve tries the smallest change that clears failed checks. The design is kept (designId) for tendon_write. Read-only.
Tool call template
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "tendon_design"
}
}Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| keep | No | autoResolve: what it must not change. improve default: anchors, count, strandsPerTendon and duct kept, profile free; new default: nothing kept. | |
| mode | No | new = auto-design new tendons; improve = read the model's own tendons on the girder and check / improve them. Default: improve when tendons run along the girder, else new. | |
| group | No | Structure group holding ONE girder's beam elements - the elements one continuous tendon runs through, end to end (not the whole deck). A group holding several girders is split into its girder lines and one is designed (girderLine). | |
| forces | No | Where the forces come from. Default: CIVIL NX - construction-stage results when the model has stages (the construction-stage analysis must have been run), else static load cases. | |
| settings | No | Loads & prestress values that differ from the model / plugin defaults. | |
| debonding | No | Pre-tensioned only: strands sleeved (debonded) at the beam ends so they carry no force there - relieves transfer tension at the ends. "auto" = the plugin's Find debonding on the strands as designed (pairs of inner strands, 1-6 m, within 25 % of all strands and 40 % of a row, outermost strands bonded; taken only if checks improve); "none" = every strand bonded (auto-design does not debond either); or a list giving exactly the strands to sleeve, by name as design.debonding.strandNames lists them (standard positions like "A.5", or tendon numbers on a tendon grid). Omitted: as auto-design left it (on a standard precast beam it may already debond). Written to CIVIL NX as each strand's DeBondBLEN / DeBondELEN. | |
| lineLoads | No | forces.source beam: superimposed dead and live line loads, kN/m. | |
| startNode | No | The girder end its stations are measured from (default: the end the elements run from). | |
| elementIds | No | The girder's beam elements (one girder line). | |
| girderLine | No | When the group/elements hold several separate girders: which one to design (1-based, as listed in girderNotes). Default: the one with the most tendons on it. | |
| autoResolve | No | When checks fail, try the smallest change that clears them (the plugin's Auto-resolve); taken only if fewer checks fail. | |
| useSelection | No | Use the beam elements selected in CIVIL NX (one girder line). | |
| columnStrands | No | Strands per tendon, column by column (left to right, as design.columns lists them); null = the design's strandsPerTendon. A column with its own count is written with its own tendon property. Post-tensioned draped tendons only (not standard strand patterns). | |
| compositeMode | No | Composite girder (precast girder + deck slab section): when the tendons are stressed. before = prestress, girder and wet-slab weight on the girder alone, superimposed dead and live load on the composite section (precast / pre-tensioned); after = the slab has hardened, prestress on the composite section too; off = ignore the slab. Default: worked out from the construction stages (first stressing stage vs the slab's CSCS stage), else before. The slab's concrete is read from the model (CSCS, else the section's Es/Ec). | |
| externalTendons | No | mode new, post-tensioned box or U girders: add external tendons in the void (CIVIL NX External tendon type), straight between deviators - anchored at the centroid, low at 0.3 and 0.7 of each span just clear of the bottom slab, high over interior supports. Added before the internal tendons are sized, so those are sized with them in place. | |
| sectionNodeLine | No | Only when CIVIL NX will not send the section records: the node line (top, centroid, bottom) the tendon heights are measured from. Worked out from the model otherwise. | |
| standardStrands | No | mode new: a section named after a UK/Irish standard precast beam (Y, TY, SY, M, U, W ...) is pre-tensioned on the beam's published strand positions. false (or settings.prestressType "post") post-tensions it instead. | |
| compositeSection | No | Old name of compositeMode: girder = before, whole = after. |