Alpaca4d

Appearance

Double L-Angle ​

Two equal L-angles placed back to back with a gap between them — the usual arrangement for a truss chord or a bracing member bolted through a gusset plate.

🔧 Grasshopper component ​

2LAngleCS (Alpaca4d) — Alpaca4d ▸ 01_Section, nickname 2L

2L component
Inputs
SecNameSectionNameText(empty)Label for the section.
HeightNumber0.10First leg dimension, in m.
WidthNumber0.10Second leg dimension, in m.
ThicknessNumber0.01Leg thickness, in m.
GapNumber0.02Clear distance between the two angles, in m — typically the gusset plate thickness.
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 back-to-back double angle: truss chords and diagonals, bracing, light lattice members.

Do not use it when

  • The profile is a catalogue angle → Steel Section Library, family 2L, which has 87 of them and exposes the same Gap input.
  • The two angles are not connected along their length. This section assumes they act compositely; two separate members would be the honest model.

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

The properties are those of the pair, computed about the combined centroid, with the angles offset by Gap/2 either side of the local z axis.