Alpaca4d

Appearance

I Section ​

An I-shaped (H-shaped) cross-section, allowed to be asymmetric: the top and bottom flanges have independent widths and thicknesses.

🔧 Grasshopper component ​

I SectionAlpaca4d ▸ 01_Section
I Section component
Inputs
SecNameSectionNameText(empty)Label for the section.
HeightNumber0.3Overall height, in m.
TopFlangeWidthNumber0.15Width of the top flange, in m.
TopFlangeThicknessNumber0.02Thickness of the top flange, in m.
BottomFlangeWidthNumber0.20Width of the bottom flange, in m.
BottomFlangeThicknessNumber0.02Thickness of the bottom flange, in m.
WebNumber0.02Web thickness, in m.
MaterialMaterialA Uniaxial material.
ColourColour(empty)The colour the section is drawn in when Model View colours the elements by section.
Left empty, Model View gives each section a colour of its own. Display only: the analysis never reads it.
Outputs
SectionSectionBeam section, for a ForceBeamColumn.

📈 When to use it ​

Use it when

  • The member is a welded plate girder, or any I-profile that is not in the catalogue.
  • The section is monosymmetric — a composite beam approximated with a wide bottom flange, a crane girder.

Do not use it when

  • The profile is a rolled IPE, HEA, HEB or similar → Steel Section Library, family I, which has 90 of them and gets the root radii right.

🔗 Relation to OpenSees
tcl
section Elastic $secTag $E $A $Izz $Iyy $G $J $alphaY $alphaZ