Bilin Material

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This command is used to construct a bilin something or other

uniaxialMaterial Bilin $matTag $K0 $as_Plus $as_Neg $My_Plus $My_Neg $Lamda_S $Lamda_C $Lamda_A $Lamda_K $c_S $c_C $c_A $c_K $theta_p_Plus $theta_p_Neg $theta_pc_Plus $theta_pc_Neg $Res_Pos $Res_Neg $theta_u_Plus $theta_u_Neg $D_Plus $D_Neg

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$matTag	integer tag identifying material
$K0	elastic stiffness
$as_Plus	strain hardening ratio for positive loading direction
$as_Neg	strain hardening ratio for negative loading direction
$My_Plus	effective yield strength for positive loading direction
$My_Neg	effective yield strength for negative loading direction
$Lamda_S	Cyclic deterioration parameter for strength deterioration
$Lamda_C	Cyclic deterioration parameter for post-capping strength deterioration
$Lamda_A	Cyclic deterioration parameter for acceleration reloading stiffness deterioration (is not a deterioration mode for a component with Bilinear hysteretic response).
$Lamda_K	Cyclic deterioration parameter for unloading stiffness deterioration
$c_S	rate of strength deterioration
$c_C	rate of post-capping strength deterioration
$c_A	rate of accelerated reloading deterioration
$c_K	rate of unloading stiffness deterioration
$theta_p_Plus	pre-capping rotation for positive loading direction (often noted as plastic rotation capacity)
$theta_p_Neg	pre-capping rotation for negative loading direction (often noted as plastic rotation capacity)
$theta_pc_Plus	post-capping rotation for positive loading direction
$theta_pc_Neg	post-capping rotation for negative loading direction
$Res_Pos	residual strength ratio for positive loading direction
$Res_Neg	residual strength ratio for negative loading direction
$theta_u_Plus	ultimate rotation capacity for positive loading direction
$theta_u_Neg	ultimate rotation capacity for negative loading direction
$D_Plus	rate of cyclic deterioration in the positive loading direction (this parameter is used to create assymetric hysteretic behavior for the case of a composite beam)
$D_Neg	rate of cyclic deterioration in the negative loading direction (this parameter is used to create assymetric hysteretic behavior for the case of a composite beam)

Image from Lignos, D. G., Krawinkler, H. and Whittaker, A.S. (2010). "Prediction and validation of sidesway collapse of two scale models of a 4-story steel moment frame", Earthquake Engineering and Structural Dynamics, EESD, (Accepted for publication, June 14th 2010).

(2009). “Sidesway Collapse of Deteriorating Structural Systems under Seismic Excitations,” Technical Report 172, The John A. Blume Earthquake Engineering Research Center, Department of Civil Engineering, Stanford University, Stanford, CA.

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Code Developed by : by Dr. Dimitrios Lignos, McGill University and was implemented by Dr. Theodore Karavasilis, Oxford University