Georgia Tech
CEE

Introduction

As the world’s population grows, the vulnerability to catastrophic events becomes more pronounced. According to the 2002 report of The International Federation of Red Cross and Crescent Societies [1], earthquakes affected 19 million peoOverturning of building on mat foundation 1999 Adapazari Earthquake, Turkey - Date & Time (UTC): Aug 17, 00:01:39, Magnitude: Mw 7.6 (Source: Geotechnical Engineering Photo Album by Prof. R.W. Boulanger & J.M. Duncan) ple in the year 2001 alone - more than any other year of the previous decade - and accounted for over a half of the year’s death toll. Realistic ground motion predictions of future earthquakes and their impact on the built environment implies advancement of the understanding and characterization of seismic ground motion, which can be only achieved by combining source, wave-propagation, site-response and soil-structure interaction. An important step towards this goal is the consensus that exists nowadays between the earthquake engineering and seismological community that the response of soft sediments to strong ground motion can significantly aggravate the catastrophic consequences of large earthquakes, while the dynamic interaction of the foundation elements with the surrounding soil may play “beneficial or detrimental”[2] role to the response of the superstructure depending on the ground motion intensity, site conditions and foundation characteristics.

Fortunately, the recently increasing number of seismic response observations has contributedtowards our improved understanding of nonlinear site effects and soil-structure interaction phenomenaLiquefaction & lateral spreading in the Port of Kobe - 1995 Hyogoken-Nanbu (Kobe) Earthquake, Japan - Date & Time(UTC) : Jan.16, 20:46:52, Magnitude : Mw 6.8 (Source: Prof. M. Yoshimine, Soil Mechanics Laboratory, TMU). According to the National Research Council (NRC) report on Improved Seismic Monitoring-Improved Decision-Making [3]: “…Thedevelopment of successful risk management strategies for earthquake hazards requires that the benefits from reduced uncertainty provided by seismic monitoring are integrated with the factors that influence risk perceptionand choice. The extent to which information from seismic monitoring networks can be used to reduce losses from future earthquakes depends, to a large degree, on providing this information to decision-makers and other end-users in an appropriate form, and on the extent to which these individuals and groups understand and make use of the information. With appropriate information, decision-makers can develop effective mitigation strategies to reduce the impacts of low probability, high-loss earthquake events….].
Through seismic activity monitoring, each event provides a unique learning opportunity, leadingto a more complete understanding of geophysical processes, more effective hazard mitigation strategies, and improved emergency response and recovery.

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Our research interests

Failure of bridge abutment backfill - 1999 Chi-Chi Earthquake, Taiwan - Date & Time(UTC) : Sep.20, 14:47:18, Maginitude : Mw 7.5 (Source: Prof. M. Yoshimine, Soil Mechanics Laboratory, TMU)Our research interests focus on investigating the response of the built environment in the occurrence of natural hazards (i.e. strong earthquakes, hurricanes, tsunami etc.). These problems require an inter­disciplinary effort of the seismological, geophysical, and civil engineering/offshore engineering commu­nities and involve the understanding of the response of soil formations subjected to extreme dynamic loads (e.g. seismic excitation, wind loading, deep and shallow-water waves) and the resulting dynamic response of the superstructures accounting for phenomena of soil-foundation-structure interaction.
Until recently, semi-analytical and numerical simulations of the nonlinear transient response of soil formations and founLandslide - 1994 Hokkaido-Toho-oki Earthquake, Japan (Earthquake off the East Coast of Hokkaido) - Date & Time(UTC) : Dec.28, 12:19:24, Maginitude : Mw 7.7 (Source: Prof. M. Yoshimine, Soil Mechanics Laboratory, TMU)dation elements have relied -and were

successively evaluated- on laboratory testing results, which would almost entirely provide critical con­straints on the interpretation methodologies and real in-situ material behavior, due to the lack of ground motion and superstructure response recordings during high intensity seismic events.
With the emerging technology of sensor networks and downhole instrumentation that have been increasingly deployed in seismically active areas over the past years, the “Geotechnical Earthquake Engineering & Geophysics” group at GATech is pursuing interdisciplinary research integrating forward and inverse ground motion analyses and soil-foundation-structure interaction simulations with emerging data acquisition technologies. Objective of our work to use fundamental principles and high quality data to evaluate the applicability of existing design methodologies and develop new techniques that will replace the phenomenological state-of-practice in earthquake engineering and strong motion seis­mology, allowing efficient and cost-effective credible ground motion and structural response predictions.

Here are some of our research interests:

  • Numerical methods in geotechnical earthquake engineering
  • Finite element simulation of coupled soil-structure interaction problems
  • Broadband motion site response: From rupture models to engineering design
  • Weak motion downhole array inversion: Decoupling energy absorption(damping) from scattering in the near surface
  • Strong motion site response inversion:  Understanding the transient soil behavior in-situ
  • Numerical simulations of topography-soil-structure interaction effects: Development of design correction factors

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Surface rupture of thrust fault (2m vertical offset) - 1999 Chi-Chi Earthquake, Taiwan - Date & Time(UTC) : Sep.20, 14:47:18, Maginitude : Mw 7.5 (Source: Prof. M. Yoshimine, Soil Mechanics Laboratory, TMU) Failure of bridge abutment backfill - 1999 Chi-Chi Earthquake, Taiwan - Date & Time(UTC) : Sep.20, 14:47:18, Maginitude : Mw 7.5 (Source: Prof. M. Yoshimine, Soil Mechanics Laboratory, TMU) Failure of waterfront structure 1995 Hyogoken-Nanbu (Kobe) Earthquake, Japan - Date & Time(UTC) : Jan.16, 20:46:52, Magnitude : Mw 6.8 (Source: Prof. M. Yoshimine, Soil Mechanics Laboratory, TMU) Numerical Model