CEE Seminar: Dynamic Soil-structure Interaction in Buildings with Deep Basements

McDonnell Douglas Engineering Auditorium (MDEA)
Christian Ledezma, Ph.D.

Associate Professor
Pontificia Universidad Catolica de Chile

Abstract: The construction of tall buildings has been increasing worldwide, creating new challenges in earthquake engineering and design. Prior studies and existing seismic design guidelines have indicated that the current fixed-base hypothesis for evaluating the seismic response of structures is not sufficient to properly represent the boundary conditions and behavior of tall buildings with basement levels. Studies of soil-structure interaction (SSI) for tall buildings have, however, typically been inconclusive. It is not clear under which conditions consideration of soil-basement-structure interaction (SBSI) is necessary for the design of the superstructure, foundation and basement levels and when it can safely be avoided. An experimental numerical approach is presented to better understand the seismic response of tall buildings with basement levels, considering explicit SBSI modeling. Chilean tall buildings and soil conditions are used as study cases, analyzed using nonlinear finite element analyses in conjunction with results from centrifuge experiments. The results show how seismic response changes when SBSI is appropriately incorporated.

Bio: Christian Ledezma is an associate professor at the Pontificia Universidad Católica de Chile (PUC). He has bachelor's and master's degrees from PUC, and a master's degree and doctorate from UC Berkeley. He is currently the vice president of ACHISINA, Chile’s Association of Earthquake Engineering, and an active member in the discussion and elaboration of Chilean seismic codes. At PUC, he teaches courses in geotechnical earthquake engineering and deep foundations. He is currently head of the Structural and Geotechnical Engineering Department at PUC. Ledezma has conducted post-earthquake reconnaissance investigations following the last three major Chilean earthquakes (Maule 2010 Mw8.8, Iquique 2014 Mw8.2, and Illapel 2015 Mw8.4), and the Mw7.1 Puebla 2017 Mexico earthquake. His main areas of interest are soil-structure interaction, soil liquefaction and geotechnical earthquake engineering. He is currently a visiting scholar in the U.S. thanks to a Fulbright scholarship.