topic Re: Shell polygonal tower in Robot Structural Analysis Forum

Shell polygonal tower

simas.lembartas25CSD — Tue, 04 Aug 2026 13:16:10 GMT

Hello,

i am trying to model a tapered polygonal tower in shell. When i do extrude with scale for a circle, it works perfectly, bet when i do that with 12 n polygon, it does it like that. How can i make this right?

Re: Shell polygonal tower

Krzysztof_Wasik — Wed, 05 Aug 2026 07:22:31 GMT

Hi @simas.lembartas25CSD

I am not sure what method you are using for such tower definition bot maybe you could consider using library (parmetrised) structure to simulate such geometry

Re: Shell polygonal tower

simas.lembartas25CSD — Wed, 05 Aug 2026 10:54:19 GMT

Thank you i will try. I am trying to model a polygonal monopile tower. So this way it is modeled as 12 nodes polygon and not a circle section, yes?

Re: Shell polygonal tower

Krzysztof_Wasik — Wed, 05 Aug 2026 12:11:32 GMT

Hi @simas.lembartas25CSD

Yes library tower is based on parametrized polygons.

Re: Shell polygonal tower

simas.lembartas25CSD — Thu, 06 Aug 2026 04:57:54 GMT

So to be sure, if i divide it to 12 nodes, i get a model for this:

Re: Shell polygonal tower

Stephane.kapetanovic — Mon, 10 Aug 2026 06:29:52 GMT

HI @simas.lembartas25CSD

Note that, in addition to what @Krzysztof_Wasik suggested, you can also create a faceted cone by specifying the number of edges (for example, 12), along with the height and the section dimensions.

https://help.autodesk.com/view/RSAPRO/2027/ENU/?guid=GUID-66D8C755-044F-4E08-9DAF-A3DE87B57247

You may also need to account for varying plate thicknesses, overlaps, and additional components such as manholes, branch connections, base plates, and cover plates. If you are working from a drawing, another option is to model the structure using simple plates based on a reference layout or a 3D wireframe imported from AutoCAD.

A finite element model can be very useful for validating and refining the design. However, in many cases, a parallel beam model can provide a much faster way to size the structure, with the finite element model then used to verify the final design.

https://help.autodesk.com/view/RSAPRO/2027/ENU/?guid=GUID-EC5FD1DC-602A-4D1D-A1E6-2D41A750B1C9

Best Regards

Re: Shell polygonal tower

simas.lembartas25CSD — Thu, 06 Aug 2026 07:33:02 GMT

Thank you for your insight. When i try to model it from panels, it does calculations for few hours, but if i do that with cone or the method suggested by Krzysztof_Wasik, it does calculations quickly.

Re: Shell polygonal tower

Stephane.kapetanovic — Thu, 13 Aug 2026 04:51:16 GMT

All these examples show that it is possible to access modeling functions in various ways and that modeling is easy.

Keep in mind that if your product is parametric, it is possible to automate modeling and calculations via the API. Many manufacturers are moving in this direction to automate their design processes once the procedures are established. Using shell elements instead of transformed objects provides greater flexibility for meshing and adding accessories.

' Creates a 3-segment tapered dodecagon mast (12-sided polygonal shell) ' Base diameter: 0.95m, Top diameter: 0.35m, Total height: 25m Sub BuildTruncatedDodecagoneMast() Dim app As RobotApplication: Set app = New RobotApplication Dim o As RobotObjObjectServer: Set o = app.Project.structure.objects Const H = 25, db = 0.95, dt = 0.35, S = 3, E = 12, HS = H / S Dim pb As New RobotPointsArray, pt As New RobotPointsArray, pf As New RobotPointsArray pb.SetSize E: pt.SetSize E: pf.SetSize 4 Dim tsl As RobotLabel, tsd As IRobotThicknessData, tsh As IRobotThicknessHomoData Dim labels As RobotLabelServer: Set labels = app.Project.structure.labels Dim MaxT%, tArr As Variant: tArr = Array(12, 10, 8): MaxT = UBound(tArr) For Each t In tArr Set tsl = labels.Create(IRobotLabelType.I_LT_PANEL_THICKNESS, ThkName(t)) Set tsd = tsl.data: tsd.MaterialName = "Q345": tsd.ThicknessType = I_TT_HOMOGENEOUS Set tsh = tsd.data: tsh.ThickConst = (t - 0.04) / 1000 labels.Store tsl Next t o.BeginMultiOperation Dim thk$, i%, j%, k%, n%, id% Dim hb#, ht#, Rb0#, Rt0#, dr#: Rb0 = db / 2: Rt0 = dt / 2: dr = (Rt0 - Rb0) / H For i = 0 To S - 1 hb = i * HS: ht = hb + HS Fill pb, E, hb, Rb0 + dr * hb Fill pt, E, ht, Rb0 + dr * ht k = i: If i > MaxT Then k = MaxT thk = ThkName(tArr(k)) For j = 1 To E If j = E Then n = 1 Else n = j + 1 CopyPt pb, j, pf, 1: CopyPt pb, n, pf, 2: CopyPt pt, n, pf, 3: CopyPt pt, j, pf, 4 id = o.FreeNumber: o.CreateContour id, pf With o.Get(id): .Main.Attribs.Meshed = 1: .SetLabel I_LT_PANEL_THICKNESS, thk: .Initialize: End With Next Next o.EndMultiOperation: app.Project.viewMngr.Refresh End Sub Function ThkName(t As Variant) As String ThkName = "THK_" & t & "_HDG" End Function Sub Fill(p As RobotPointsArray, n%, z#, r#) Dim a#: a = 6.28318530717959 / n: For i = 0 To n - 1: p.Set i + 1, r * Cos(i * a), r * Sin(i * a), z: Next End Sub Sub CopyPt(src As RobotPointsArray, i%, dst As RobotPointsArray, k%) Dim x#, y#, z#: src.Get i, x, y, z: dst.Set k, x, y, z End Sub

Beyond modelling the shaft, the API can automate much more: connections, arm attachments, slip-joint overlaps, climatic loads (wind, seismic, ice), and code checks across several standards at once and behind a revamping project, there's often a code upgrade and ageing structure to account for too: GB, Eurocode, TIA-222, ASCE/SEI 48 + MOP 74, EN 50341. That makes it practical to compare standards or sweep many configurations in reasonable time.

On the innovation side, this can now connect to AI tools via an MCP server: an assistant can drive the model directly in natural language, generating geometry and running checks, while the engineer simply describes what to verify.

Programs can be written as a single block or, better, built in layers : more flexible, easier to maintain, and reusable across projects.

Best Regards

Re: Shell polygonal tower

bhavani_sankuratri — Sun, 09 Aug 2026 09:26:41 GMT

Hi @simas.lembartas25CSD ,

Hope you are doing good! I wanted to check whether the solution shared by Stephane.kapetanovic helped with your polygonal tower model. If you are still having trouble, please let us know.