FCS Steel Design Library

Fcs.SteelLib is a built-in namespace providing thin-walled cold-formed section geometry, material definitions, connection categories, and Ultimate Limit State (ULS) design checks.

1. Namespace Overview

2. Section Geometry (Z-Section Example)

# from new-FcsSteelLib/designTest.fcs
zsect := Fcs.SteelLib.Sections.Zsection.sectionGsi_6Z12(
    Fcs.SteelLib.Sections.Materials.CommonSteel,
    Fcs.SteelLib.Sections.Connection.WithoutBolting
)

The returned zsect object contains the section geometry (vertex positions, areas, moments of inertia) and the material properties as a compound record.

Other section constructors

The pattern Fcs.SteelLib.Sections.<SectionFamily>.<catalogueFunction>(material, connection) applies to all section families:

Catalogue function names encode the cross-section dimensions: 6Z12 means 6-inch Z-section with 12-gauge thickness.

3. Materials

4. Connection Categories

5. Shape Conversion

Before passing a section to a design function, convert it to a Shape object:

shape := Fcs.SteelLib.Sections.Shape.shapeFromZet(zsect)

6. ULS Design Checks

Tension ultimate

Nrd := Fcs.SteelLib.Design.ULS.TensionUltimate(shape)
# returns design tensile resistance Nrd [N]

Other available checks (pattern: Fcs.SteelLib.Design.ULS.<Check>(shape, ...))

7. Integrating with CharacteristicsSolver

For custom or compound sections not in the catalogue, use CharacteristicsSolver (see 14-BEAM-ADVANCED.md) to compute the elastic properties, then feed them manually into the analysis:

ch := Fcs.Analysis.BeamSection.CharacteristicsSolver(customCss).Result
cross_section {cs1} geometry_class (customCss) material 1 parameters {
    A  = ch.EA,
    Iy = ch.EIyc,
    Iz = ch.EIzc
}

8. Defining Cross-Section Geometry with filletedpoly (inline vertex-list syntax)

The catalogue sections are internally built with filletedpoly. You can also define a custom thin-walled profile manually using the vertex-list form of filletedpoly:

# vertices listed inline; fillet radii listed separately after `fillets`
curve {cProfile} filletedpoly radiusmultiplier 1
    vertexes {v1} {v2} {v3} {v4} {v5} {v6} ...
    fillets   0   r1   r1   r1   r1   0  ...

area {aCss} boundary curve {cProfile}

This differs from the items (array) form in doc 13 — both are valid. Use the vertex-list form when vertices are separately declared and can be referenced by name; use the items (array) form when constructing the profile from a data array at runtime.

Source file

TestData/new-HieSolver5/css/2C_profile.fcs

9. Complete Design Example

# --- Section and material ---
zsect := Fcs.SteelLib.Sections.Zsection.sectionGsi_6Z12(
    Fcs.SteelLib.Sections.Materials.CommonSteel,
    Fcs.SteelLib.Sections.Connection.WithoutBolting
)

# --- Convert to shape for design checks ---
shape := Fcs.SteelLib.Sections.Shape.shapeFromZet(zsect)

# --- ULS tension check ---
Nrd := Fcs.SteelLib.Design.ULS.TensionUltimate(shape)

# --- Apply to beam in analysis ---
cross_section {cs1} geometry_class (zsect.Geometry) material 1 parameters {
    A=zsect.A, Iy=zsect.Iy, Iz=zsect.Iz
}
beam {b1} type Frame curve {c1} xsection {cs1}

Source file

TestData/new-FcsSteelLib/designTest.fcs

10. Quick Reference

# Section from catalogue
zsect := Fcs.SteelLib.Sections.Zsection.sectionGsi_6Z12(
    Fcs.SteelLib.Sections.Materials.CommonSteel,
    Fcs.SteelLib.Sections.Connection.WithoutBolting )

# Shape conversion
shape := Fcs.SteelLib.Sections.Shape.shapeFromZet(zsect)

# ULS check
Nrd := Fcs.SteelLib.Design.ULS.TensionUltimate(shape)

11. Relevant Test Folders