Steel Section Library

A catalogue of 628 steel profiles embedded in Alpaca4d. Pick a family and a name, and the component builds the matching parametric section for you.

🔧 Grasshopper component

Steel Section Library (Alpaca4d) — Alpaca4d ▸ 01_Section, nickname Section Library

Inputs

NameSection NameText(empty)Type a profile name directly, e.g. IPE200.

Overrides the dropdowns and moves them to match.

MaterialMaterialElastic steelA Uniaxial material.

Defaults to Alpaca4d's elastic steel, so the component works with nothing plugged in.

GapNumber0.01Only present when the family is 2L or All. Clear distance between the two angles, in m.

The input appears and disappears as you change the family.

ColourColour(empty)The colour the section is drawn in when Model View colours the elements by section — every section of the list, with Section set to All.

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.

With Section set to All, a list of them, smallest area first.

Options

Two dropdowns live on the component body, under the Library menu:

Dropdown	Values	Default
Family	I, 2L, O, [], All	I
Section	All, then the profiles of the selected family	first profile in the family

Set Section to All for every profile of the family as a list, and Family to All for all 628. Either list is ordered by cross-sectional area, smallest first — the lightest profile at index 0 and the heaviest last — so a List Item driven by a slider walks through them by weight. Connect a Panel to the output to read the list: each section shows as its name.

Family	Profiles	Builds a	Examples
I	90	I Section	IPE80 … IPE600, HEA, HEB, HEM
O	205	Circular	26.9x2, 33.7x2.5, …
[]	246	Rectangular Hollow	40x20x2, 40x30x3, …
2L	87	Double L-Angle	L20x20x3, L25x25x4, …

📈 When to use it

Use it when

• The member is a standard rolled profile. Typing HEB300 is faster and less error-prone than entering six dimensions.
• You are running an optimisation over a discrete set of profiles — set Section (or Family) to All and pick from the list with List Item and a slider, or feed your own list of names into Section Name.

Do not use it when

• The profile is welded, tapered or otherwise not in the catalogue → use the matching parametric section.
• You only have the stiffness properties → Generic Section.

🔗 Relation to OpenSees

The library resolves to one of the parametric sections, all of which write:

section Elastic $secTag $E $A $Izz $Iyy $G $J $alphaY $alphaZ