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🧩LoadPattern

A load pattern groups one or more loads and defines how they vary in time through a time series. It is the object that Alpaca4d actually uses during analysis to apply loads to the structure.

In Grasshopper, load patterns are created with the Load Pattern component, which exposes sub‑components such as PlainPattern and UniformExcitation and produces an Alpaca4d.Loads.LoadPattern object.

Plain pattern

The PlainPattern sub‑component is used for static and quasi‑static load cases.

  • Inputs

    • TimeSeries: A time series object (e.g. Constant, Linear) that controls how the pattern factor evolves over analysis time.

    • Loads: List of load objects (point, beam/line, shell/mesh, gravity, etc.) to be included in this pattern.

    • Factor (optional): Constant scalar applied to all loads in the pattern (default = 1.0).

  • Behaviour

    • The pattern factor is obtained from the time series and multiplied by Factor and by each individual load magnitude.

    • Used for typical load cases like Dead, Live, Snow, Wind, etc.

Uniform excitation pattern

The UniformExcitation sub‑component is used to apply base acceleration (e.g. earthquake ground motion) to the entire model.

  • Inputs

    • Dof: Degree of freedom where the ground motion acts (X, Y, Z, XX, YY, ZZ).

    • TimeSeries: Time series describing the ground motion (usually acceleration vs. time).

    • Velocity (optional): Initial velocity of the base, in ([Length/time]).

    • Factor (optional): Constant scale factor for the excitation.

  • Behaviour

    • Internally creates a LoadPattern of type UniformExcitation that applies the same base motion to all support nodes in the selected direction.

Workflow

  1. Create individual load objects (point, beam/line, shell/mesh, gravity, etc.).

  2. Group them in one or more Load Pattern components (Plain or UniformExcitation).

  3. Connect the load patterns to the Assemble component together with the model and analysis settings.

This separation between loads and load patterns allows you to reuse the same loads in different patterns and to clearly organize load cases and dynamic excitations.

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