Circular

A circular cross-section, solid or hollow.

🔧 Grasshopper component

CircleCSAlpaca4d ▸ 01_Section

Inputs

SecNameSectionNameText(empty)Label for the section.

DiameterNumber0.15Outer diameter, in m.

ThicknessNumber0.01Wall thickness, in m. 0 or D/2 gives a solid circle. Anything larger than D/2 is an error.

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 circular hollow section, a pipe or a tube.
• The member is a solid round bar — set Thickness to 0.

Do not use it when

• The profile is a catalogue CHS → Steel Section Library, family O, which has 205 of them.

🔗 Relation to OpenSees

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

For a hollow circle the properties come out as A = π(D² − (D−2t)²)/4, I = π(D⁴ − (D−2t)⁴)/64 and J = 2I.