Seismic Risk

Seismic Risk

This course aims to present to the students the concepts and methods necessary to the study and evaluation of seismic risk. The course is structured with the participation of several external speakers.

The knowledge of the threat associated with the seismic risk mainly relies on the comprehension of a cascade of physical phenomena related to the seismic source, the seismic wave propagation, the local behavior of the soils close to the structures as well as the mechanical response of the structures themselves.

The related physical phenomena as well as the characterization of the ground motion during an earthquake are presented : accumulation of regional tectonic stresses, nucleation and propagation of the rupture, seismic wave generation and propagation. Attenuation and diffraction of the elastic field ; amplification of the seismic movement by the shallow structure (sedimentary basins, alluvial valleys) and by the topography.

The response of the soils close to the structures plays a determinant role. Its study requires specific concepts like the non linear behavior of soils, their behavior at dynamic loading and liquefaction.

Finally, the response of the structure itself (buildings, bridges, etc) is studied. We treat the dynamics of structures applied to the earthquake excitation and study the way in which hazard is represented for the seismological engineering (PGA, response spectrum, etc) within the context of the seismic legal codes. Structural dynamics is treated through case studies both by numerical modeling ( modal analysis ) and empirical methods. This is important in particular when addressing the question of the vulnerability of preexisting structures.