Limit State Material

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This command is used to construct a uniaxial hysteretic material object with pinching of force and deformation, damage due to ductility and energy, and degraded unloading stiffness based on ductility. Failure of the material is defined by the associated Limit Curve.


uniaxialMaterial LimitState $matTag $s1p $e1p $s2p $e2p $s3p $e3p $s1n $e1n $s2n $e2n $s3n $e3n $pinchX $pinchY

$damage1 $damage2 $beta $curveTag $curveType.


$matTag integer tag identifying material
$s1p $e1p stress and strain (or force & deformation) at first point of the envelope in the positive direction
$s2p $e2p stress and strain (or force & deformation) at second point of the envelope in the positive direction
$s3p $e3p stress and strain (or force & deformation) at third point of the envelope in the positive direction
$s1n $e1n stress and strain (or force & deformation) at first point of the envelope in the negative direction*
$s2n $e2n stress and strain (or force & deformation) at second point of the envelope in the negative direction*
$s3n $e3n stress and strain (or force & deformation) at third point of the envelope in the negative direction*
$pinchX pinching factor for strain (or deformation) during reloading
$pinchY pinching factor for stress (or force) during reloading
$damage1 damage due to ductility: D1(m-1)
$damage2 damage due to energy: D2(Ei/Eult)
$beta power used to determine the degraded unloading stiffness based on ductility, m-b (optional, default=0.0)
$curveTag an integer tag for the Limit Curve defining the limit surface
$curveType an integer defining the type of LimitCurve (0 = no curve,

1 = axial curve, all other curves can be any other integer)


NOTES:

  • negative backbone points should be entered as negative numeric values



EXAMPLE:

Original version of example:

Debugged version of example:

Manual for the example:




DESCRIPTION:

Modeling Failures in Existing Reinforced Concrete Columns by Ken Elwood: File:ElwoodCJCE2004.pdf


REFERENCES:

Elwood, K.J and Moehle, J.P., "Shake Table Tests and Analystical Studies on the Gravity Load Collapse of Reinforced Concrete Frames", Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA. PEER 2003/01.



Code Developed by: Ken Elwood, University of British Columbia