Alpaca4d

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Hinge Release ​

A hinge release is the DOF pattern of one beam end. It is consumed by the WithHinges unit of the ForceBeamColumn component, and by nothing else.

🔧 Grasshopper component ​

Hinge ReleaseAlpaca4d ▸ 02_Element
Hinge Release component
Inputs
TxBooleantrueAxial translation along x.
false = released.
TyBooleantrueTranslation along y. false = released.
TzBooleantrueTranslation along z. false = released.
RxBooleantrueTorsional rotation about x.
false = released.
RyBooleantrueRotation about y (bending).
false = released.
RzBooleantrueRotation about z (bending).
false = released.

Warning

The sense is inverted relative to what the word "release" suggests: true means held, false means released. It reads the same way as the booleans on Support, which is why it is that way round.

Outputs
ReleaseReleaseRelease condition, for the ReleaseI or ReleaseJ input of a WithHinges beam.

📈 When to use it ​

Use it when

  • You need a pinned beam end: set Ry and Rz to false.
  • You need a moment release about one axis only.
  • You are building a member that carries axial force only.

Do not use it when

  • The member is fully continuous — leave ReleaseI and ReleaseJ empty and the ends are taken as fixed.

🔗 Relation to OpenSees

There is no OpenSees release command. A released DOF becomes a hinge section with that property scaled by 10⁻⁶, placed by HingeRadau — see Beam With Hinges for the mapping from each boolean to the section property it softens.

Because the hinge is a very soft section rather than a true free end, the release is approximate. Its accuracy depends on Lp/L, which is why that ratio is clamped.