3.1.5.30. InitStrain Material Wrapper

This command is used to construct an InitStrain (or InitialStrain) uniaxial material wrapper. The wrapper imposes an initial strain on the wrapped material so that the effective strain seen by the wrapped material is the applied strain plus the initial strain. After the constructor, no special state is maintained.

uniaxialMaterial InitStrain $matTag $otherTag $eps0

Argument	Type	Description
$matTag	integer	unique material tag
$otherTag	integer	tag of a previously-defined UniaxialMaterial
$eps0	float	initial strain

Note

It is good practice to run one analysis step with dt = 0 when using initial strain (and initial stress) wrappers so that the model is in equilibrium.

Example

1. Tcl Code

uniaxialMaterial Hardening 1 3.0 1.0 0.1
uniaxialMaterial InitStrain 2 1 -0.1

2. Python Code

ops.uniaxialMaterial('Hardening', 1, 3.0, 1.0, 0.1)
ops.uniaxialMaterial('InitStrain', 2, 1, -0.1)

Code developed by: Michael H. Scott