Documentation for new uniaxial material Steel02M

source/user/manual/material/uniaxialMaterial.rst

@@ -25,6 +25,7 @@ The following subsections contain information about **$matType**
 
       uniaxialMaterials/Steel01
       uniaxialMaterials/Steel02
+      uniaxialMaterials/Steel02M
       uniaxialMaterials/Steel4
       uniaxialMaterials/ASDSteel1D
       uniaxialMaterials/ReinforcingSteel

source/user/manual/material/uniaxialMaterials/Steel02M.rst

@@ -0,0 +1,87 @@
+.. _steel02m:
+
+Steel02M Material
+^^^^^^^^^^^^^^^^^
+
+This command is used to construct the Steel02M uniaxial steel material, a modified Giuffre-Menegotto-Pinto model developed to eliminate overshooting and  creeping errors observed in Steel02. It also permits independent definition of key cyclic material parameters in the positive and negative loading directions.
+
+.. function:: uniaxialMaterial Steel02M $matTag $E $FyPos $FyNeg $alphaPos $alphaNeg $R0 $cR1 $cR2 <$a_pos $a_neg> <$etaPos $etaNeg> <$b_pos $b_neg>
+.. csv-table::
+   :header: "Argument", "Type", "Description"
+   :widths: 10, 10, 40
+
+   $matTag, |integer|, integer tag identifying material
+   $E, |float|, elastic Young's modulus
+   $FyPos, |float|, initial yield strength in the positive loading direction :math:`(\sigma_{y0}^{+})`
+   $FyNeg, |float|, initial yield strength in the negative loading direction :math:`(\sigma_{y0}^{-})`; must be negative
+   $alphaPos, |float|, strain-hardening ratio in the positive loading direction :math:`(\alpha^{+})`
+   $alphaNeg, |float|, strain-hardening ratio in the negative loading direction :math:`(\alpha^{-})`
+   $R0 $cR1 $cR2, 3 |float|, parameters to control the transition from elastic to plastic branches
+   $a_pos, |float|, cyclic isotropic hardening parameter in the positive loading direction (optional: default = 0.0).
+   $a_neg, |float|, cyclic isotropic hardening parameter in the negative loading direction (optional: default = 0.0).
+   $etaPos, |float|, saturation-to-initial-yield-strength ratio in the positive loading direction :math:`(\eta^{+})` (optional: default = 1.5).
+   $etaNeg, |float|, saturation-to-initial-yield-strength ratio in the negative loading direction :math:`(\eta^{-})` (optional: default = 1.5).
+   $b_pos, |float|, isotropic hardening rate parameter in the positive loading direction :math:`(b^{+})` (optional: default = 0.8). 
+   $b_neg, |float|, isotropic hardening rate parameter in the negative loading direction :math:`(b^{-})` (optional: default = 0.8).
+
+.. note::
+
+   Recommended values: $R0=between 10 and 20, $cR1=0.925, $cR2=0.15
+
+
+.. _fig-steel02m:
+
+.. figure:: figures/Steel02M/Steel02M_LivePlot.gif
+	:align: center
+	:figclass: align-center
+
+	Comparison of stress-strain response using Steel02 and Steel02M
+
+
+.. figure:: figures/Steel02M/Steel02MParametric.jpeg
+	:align: center
+	:figclass: align-center
+
+	llustration of the additional features incorporated in the Steel02M material model, showing independent definitions in the positive and negative directions of: (a) strain hardening ratios, (b) initial yield strengths, (c) isotropic hardening rates, and (d) saturation-to-initial yield strength ratios
+
+
+
+.. admonition:: Example
+
+   Download the Steel02M examples: :download:`Steel02M_Example.rar <Steel02M_Example.rar>`. The archive contains the input files; recorder output files are generated when the model is executed.
+
+   The following example defines a ``Steel02M`` material using all material parameters. For additional examples and implementation details, see `Steel02M GitHub repository <https://github.com/Kolay-IITK/Steel02M>`_.
+
+   .. code-block:: tcl
+
+      set matTag    1
+      set E         200000.0
+      set FyPos     300.0
+      set FyNeg     -300
+      set alphaPos  0.0196
+      set alphaNeg  0.0196
+      set R0        20.0
+      set cR1       0.916
+      set cR2       0.15
+      set a_pos     0.05
+      set a_neg     0.074
+      set etaPos    1.50
+      set etaNeg    1.50
+      set b_pos     0.80
+      set b_neg     0.80
+
+      uniaxialMaterial Steel02M $matTag $E $FyPos $FyNeg $alphaPos $alphaNeg $R0 $cR1 $cR2 $a_pos $a_neg $etaPos $etaNeg $b_pos $b_neg
+
+References
+==========
+
+Kolay, C., Karmakar, S., Kumar, B., and Kakoty, H. (2026). *An Improved Giuffré–Menegotto–Pinto Model: Implementation in OpenSees and Verification With Experimental Results.* Earthquake Engineering & Structural Dynamics. DOI: https://doi.org/10.1002/eqe.70266
+
+
+Code inquiry or bug reporting 
+==========
+
+- Chinmoy Kolay, Indian Institute of Technology kanpur, e-mail: ckolay@iitk.ac.in
+- Sukanya Karmakar, Indian Institute of Technology kanpur, e-mail: sukanyak@iitk.ac.in
+- Baban Kumar, Indian Institute of Technology kanpur, e-mail: babank@iitk.ac.in
+- Hironmoy kakoty, Indian Institute of Technology kanpur, e-mail: kakoty@iitk.ac.in