BidirectionalSection

BidirectionalSection(user_name: str = 'Unnamed', *, E: float, Fy: float, Hiso: float, Hkin: float)

Bases: Section

Coupled bidirectional plasticity section for specialized components.

This section type represents a material with a coupled bidirectional force-deformation relationship. It is typically used to model components with a circular yield surface, where plasticity in two orthogonal directions is dependent on the total resultant force (e.g., specialized isolation bearings or friction devices).

Tcl form

section Bidirectional <tag> <E> <Fy> <Hiso> <Hkin>

Note

The section uses an explicit integration algorithm in OpenSees for the plastic flow.
Hiso and Hkin define the isotropic and kinematic hardening moduli, respectively.
This section only resists forces in two local directions.

Tip

Use this section for modeling structural components where circular interaction between local axes is critical for capturing energy dissipation.

Example

from femora.core.model import Model
import femora.components.section.special  # noqa: F401

model = Model()
sec = model.section.special.bidirectional(
    user_name="IsolatorShear",
    E=100.0,
    Fy=1.0,
    Hiso=0.0,
    Hkin=0.02,
)
print(sec.tag)

Create a BidirectionalSection with validated parameters.

Parameters:

Name	Type	Description	Default
`user_name`	`str`	User-specified name for the section.	`'Unnamed'`
`E`	`float`	Elastic modulus.	required
`Fy`	`float`	Yield force.	required
`Hiso`	`float`	Isotropic hardening modulus.	required
`Hkin`	`float`	Kinematic hardening modulus.	required

Raises:

Type	Description
`ValueError`	If parameters are not numeric, if E or Fy are non-positive, or if hardening moduli are negative.