OpenSEES-BoucWenGG

Implementation in OpenSEES of the Bouc-Wen model modified by Gerolymos and Gazetas (2005).

Author: Andrea Marchi ([email protected])

References:

• Gerolymos N. and Gazetas G. Constitutive model for 1-D cyclic soil behaviour applied to seismic analysis of layered deposits. Soils and Foudations, 45-147 (2005).
• Marchi A. Improved Bouc-Wen model implementation in OpenSees. Proceedings of the 2022 Eurasian OpenSees Days. EOS 2022. Lecture Notes in Civil Engineering, vol 326, 31-38. Springer, Cham. https://doi.org/10.1007/978-3-031-30125-4_3

Usage (TLC):

Include BoucWenGG.dll file inside the same folder of the TCL model file to use the material. The material can be defined by the TCL command:

uniaxialMaterial BoucWenGG $matTag $alpha $k0 $strainY $n $gamma $beta $s1 $s2 $mkur

parameter	description
matTag	integer tag identifying the material
alpha	ratio of the post-yielding stiffness to the initial elastic stiffness
k0	initial elastic stiffness
strainY	yielding strain $\varepsilon_y$
n	parameter that controls the transition between the initial and post-yielding branch. As $n$ increases the transition becomes sharper (when $n\to\infty$ the model is piece-wise linear).
gamma, beta	parameters that control the shape of the hysteresis loop
s1, s2	control the stiffness degradation upon reversal
mkur	account for stress and tangent stiffness modification proposed by Drosos et al. (2012). mkur=1 modification is aplied, mkur=0 modification is not applied

Main behaviour

$F(u(t)) = \alpha \ k_0 \ u(t) + (1-\alpha) \ k_0 \ u_y \ \zeta(t)$

$\dot{\zeta}(t) = \frac{\dot{u}(t)}{u_y} [(\gamma+\beta) - |\zeta(t)|^n \ (\gamma + \beta \ sgn(\dot{u}(t) \ \zeta(t))) ] $