000010646 001__ 10646
000010646 005__ 20141205155749.0
000010646 04107 $$aeng
000010646 046__ $$k2008-10-12
000010646 100__ $$aLenti, Luca
000010646 24500 $$aDynamic Soil Response for Strong Earthquakes: A Simplified Non Linear Constitutive Model

000010646 24630 $$n14.$$pProceedings of the 14th World Conference on Earthquake Engineering
000010646 260__ $$b
000010646 506__ $$arestricted
000010646 520__ $$2eng$$aThe seismic soil response can be analyzed in the frequency (linear or equivalent linear approaches) as well as in the time domain (e.g. complex constitutive models). The nonlinear constitutive properties of soils being difficult and costly to determine, the present work proposes a simplified constitutive model to analyze the dynamic soil response for moderate or strong earthquakes at large scales (alluvial basins). In this work, we consider a non linear viscoelastic constitutive model involving both non linear elasticity as well as non linear viscous behavior. The non linear elastic part of the model is described by a hyperbolic law. The description of the viscosity starts from a Nearly Constant Quality Factor (NCQ) model able to fulfil the causality principle for seismic wave propagating in dissipative materials. In the NCQ model, we introduced a dependence on the excitation level in order to consider the variations of moduli and the increasing damping ratio. This dependence is controlled during the 3D stress-strain path by the variation of the second order invariant of the strain tensor. Applications are performed to study the rheological response of the materials without considering wave propagation, and then to study the effects of nonlinearity on the generation of higher harmonics and shift of spectral frequencies during wave propagation in a sedimentary layer. Starting from the here proposed mechanical formulation including the main features of soil nonlinear behavior, the analysis of the nonlinear response of a sedimentary layer submitted by a vertical SH wave is then performed thanks to a discretization by the finite element method. Validations of the model for different inputs show its ability to recover low amplitude ground motion response. For larger excitation levels, the analysis of wave propagation in sedimentary layer leads to interesting results: at the free-surface the spectral peaks are shifted to lower frequency values (when compared to the input motion); higher frequency components are not overdamped as for the equivalent linear model; the amplification level is generally lower. These results show the ability of this simplified nonlinear model to investigate, in the near future, site effects in 2D/3D alluvial deposits for strong earthquakes.

000010646 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000010646 653__ $$asite effects, amplification, strong motion, nonlinear behavior, viscoelasticity

000010646 7112_ $$a14th World Conference on Earthquake Engineering$$cBejing (CN)$$d2008-10-12 / 2008-10-17$$gWCEE15
000010646 720__ $$aLenti, Luca$$iSemblat, Jean-Francois$$iDelepine, Nicolas$$iBonnet, Guy
000010646 8560_ $$ffischerc@itam.cas.cz
000010646 8564_ $$s220316$$uhttps://invenio.itam.cas.cz/record/10646/files/03-03-0069.pdf$$yOriginal version of the author's contribution as presented on CD, Paper ID: 03-03-0069.
000010646 962__ $$r9324
000010646 980__ $$aPAPER