Título del libro: Proceedings Of The 4th International Conference On Soft Soil Engineering - Soft Soil Engineering
Título del capítulo: A simplified plastic hysteretic model for multi-directional nonlinear site response in soft soils
JUAN MANUEL MAYORAL VILLA; MIGUEL PEDRO ROMO ORGANISTA;
Autores externos:
Idioma:
Año de publicación:
2007
Palabras clave:
ABS resins; Clay minerals; Curve fitting; Damping; Deformation; Finite element method; Hysteresis; Plastic deformation; Plastics; Pore pressure; Soil mechanics; Soils; Stiffness; Three dimensional; A planes; Confining pressures; Constitutive laws; Coupled analyses; Cyclic behaviors; Cyclic loadings; Damping curves; Dimensional analyses; Direct simple shears; Effective stresses; Finite elements; Free fields; High frequencies; Hysteretic behaviors; Hysteretic models; Linear behaviors; Modulus degradations; Normal stresses; Over consolidated; Permanent deformations; Simple shears; Site responses; Soft soils; Soil responses; Soil stiffnesses; State of stresses; Steady states; Two parameters; Geologic models
Resumen:
Muti-directional strong shaking associated to major earthquakes may significantly increase the amount of non-linear behavior in the free field due to generation of pore pressure that can reduce the soil stiffness and increase the permanent deformations. An existing simplified effective stress based model formulated to describe the cyclic behavior of lightly over consolidated clays in simple shear (Pestana and Biscontin, 2000) was modified to account for hysteretic behavior. The formulation assumes an idealized state of stresses representing those existing in a DSS (Direct Simple Shear) test, therefore, only a normal stress ?n and two orthogonal shears ?x and ?y are considered. Two parameters w1 and w 2 describe the perfect hysteretic behavior of the soil. These parameters are obtained throughout a study which consists on fitting with the model representative experimental modulus degradation and damping curves obtained at a given confining pressure. This paper introduces this simplified plastic hysteretic model which is able to predict hysteretic behavior, plastic deformation, and the evolution of pore pressure during cyclic loading. The constitutive model was implemented in a three-dimensional 8-noded brick finite element. A demonstration of the predictive potential of the proposed constitutive law through the analyses of some hypothetic scenarios is included, as well as comparisons between uncoupled (i.e. a plane analysis in each component of motion) and coupled analyses (i.e. a bi-dimensional analysis considering both components of motion simultaneously). Overall, coupled analyses using only the hysteretic component better predicted the measured response than the uncoupled analyses for the cases studied. The results of the analyses seem to be highly dependent on the amount of Raleigh damping used, especially for high frequencies. The consideration of plastic deformations during the simulations seems to provide a better representation of the cyclic soil response during transient and steady state conditions. © 2007 Taylor & Francis Group.
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ISBN:
0415422809
Editorial:
Tipo de producto:
Conference Paper
