Events Calendar

Astani CEE Seminar

Speaker: Dr. Dominiki Asimaki, Department of Mechanical and Civil Engineering, Caltech

Talk Title: Site effects in three dimensions: Theory, experiments and numerical simulations

Abstract:
This seminar will cover a series of studies on site effects, ranging from semi-ana¬lytical solutions of wave propagation in infinite wedges, to centrifuge experiments on topo¬graphy effects, to numerical simulations of idealized and true ground surface features subjected to seismic loading. Starting from the simplest configuration, I will first discuss our work on the response of infinite wedges, which comprises a semi-analytical solution and numerical simulations of wedge response to incident in-plane shear (SV) and compressional (P) waves. I will present results, focusing specifically on the insight that idealized features provide into the physics of wave focusing and scattering by non-flat surfaces in the context of earthquake ground motion simulations. I will then summarize results of a collaborative project that used cen¬trifuge experiments to study site effects for single, step-like slopes on the surface of shallow granu¬lar soils overlaying stiff bedrock; and I will present in detail our validated nonlinear numerical simulations of the said experiments, which we have extended to study the effects of soil stiffness and thickness, and the effects of bedrock-soil velocity contrast on the ground motion characteristics near the slope crest. Our results have shown that the inelastic response of pressure-dependent soils near the surface has a significant impact on the manifestation of topographic amplification, which may differ substantially from viscoelastic model predictions traditionally used in studies of site effects on the surface of non-flat ground. In the last part of the talk, I will present a system of dimensionless parameter¬s that we have synthesized from our semi-analytical, experimental and numerical results for the study of 3D site effects; a systematic parametric investigation of 3D site effects for idealized features; and a series of site-specific simulations at strong motion station sites in Southern California with irregular ground surface topography.







Biography: Dominiki Asimaki is a Professor of Mechanical and Civil Engineering at Caltech. She has a bachelor’s diploma in civil engineering from the National Technical University of Athens, Greece (1998), and an MS (2000) and PhD (2004) from the Department of Civil and Environmental Engineering at MIT. Her research combines geotechnical engineering, computational mechanics, and structural dynamics to study how natural and man-made geotechnical systems (ridges, valleys, dams, tunnels, building foundations, and offshore structures) respond to dynamic loading induced, for example, by earthquakes, hurricanes, and blast. She then uses results from these studies to develop predictive models for resilient design procedures for geotechnical systems, and for hazard assessment and mitigation in urban environments. Domniki is associate editor for the Journal of Computing in Civil Engineering (ASCE), for Earthquake Spectra (EERI), and for Soils and Foundations (Japanese Geotechnical Society); and she is the recipient of the 2009 Arthur Casagrande Award from the ASCE Geo-Institute and the 2012 Shamsher Prakash Research Award in Geotechnical Earthquake Engineering.



Host: Dr. Maria Todorovska

Location: Seeley G. Mudd Building (SGM) - 101

Audiences: Everyone Is Invited

Contact: Evangeline Reyes