* Multidisciplinary approach of risk assessment and management, which can provide more efficient earthquake mitigation. * Transfer of Geo-scientific and engineering knowledge to Civil Protection and insurance agents * Approaches and common practices directly related to the preparation of earthquake emergency plans * Illustrated examples of actual applications, including web sites * Case-studies and information on relevant international projects
Jean-François SEMBLAT is Head of the "Earthquakes and Vibrations" Group at the Department of Geotechnical Eng., Environment and Risks of University Paris-Est, LCPC in Paris, France and Professor at Ecole Polytechnique , Palaiseau, France.
Webpage: http://perso.lcpc.fr/semblat.jean-francois/
Publications (downloadable): http://hal.archives-ouvertes.fr/aut/semblat/
His main areas of research are focused on the propagation and amplification of seismic waves in soils and complex media, the dynamic soil-structure interaction, the development of numerical methods and tools with emphasis on the inelastic soil behaviour. He has published more than 160 papers in international scientific journals and conferences. He recently published a book with Dr Alain Pecker entitled "Waves and Vibrations in Soils" (IUSS Press), where he is presenting the current state of the art in this field and his main scientific achievements and ideas.
Abstract of his main recent scientific and research work:
- Analysis of the global resonance of alluvial basins through simplified modal approaches, based on the Rayleigh approximation. Starting from admissible 2D or 3D eigenmodes, these approaches allow a fast and reliable estimation of the fundamental frequency of geological structures.
- Investigation at the scale of an alluvial basin of the amplification of seismic waves in surface layers using the Boundary Element Method (sites of EUROSEISTEST/Volvi, Nice and Caracas). Both the geometrical irregularities (topography) and the velocity heterogeneities (lithology) have a significant influence on the amplification process. Interesting comparisons between numerical and experimental results in the weak motion range. Since the classical BEM formulation is limited for 3D applications, he contributed to a new "fast multipole" formulation for boundary integral equations in elastodynamics allowing an important reduction of the computational cost as well as the memory requirements. These new results have been published in the Geophysical Journal International (2009).
- In the case of strong seismic motion, the influence of the constitutive nonlinearities in surface layers is significant. He contributed to the formulation of a simplified nonlinear model (nonlinear viscoelasticity). It takes simultaneously into account, for increasing shear strain, the shear modulus reduction and the increase of the energy dissipation. The one-dimensional simulations performed with this simplified model lead to lower amplitudes, larger propagation delays and the generation of odd order harmonics. These results were published in the Journal of Engineering Mechanics (ASCE) in 2009.
- Considering experimental results obtained from the EUROSEISTEST experimental site (http://euroseis.civil.auth.gr), he also modelled numerically structure-soil-structure interactions allowing the determination of the parameters governing these interactions. At large scales, the interaction between an alluvial basin and a building network - or site-city interaction - has been evidenced. The coincidence between the eigen frequencies of the structures and the fundamental frequency of the basin strongly influences the site-city interaction. The coherency of the wave field, the effects of the urban density and the building heterogeneity have also been studied. These results have been published in the Bulletin of the Seismological Society of America in 2008.
