ASCE Geo-Institute Technical Presentation

ABSTRACTS

Empirical Linear Seismic Site Amplification in Central  and Eastern North America by Grace Parker University of California Los Angeles

This presentation focuses on the development of empirical linear site amplification models conditioned on time-averaged shear wave velocity in the upper 30 m (V_S30) for central and eastern North America. The models are derived from ground motion data and site condition information from the NGA-East project and are intended for use with reference rock ground motion models. Site amplification is found to scale with V_S30 for intermediate to stiff site conditions (V_S30 > 300 m/s) in a weaker manner than for active tectonic regions such as the Western US. For stiff sites (> 800 m/s), we find differences in site amplification for previously glaciated and non-glaciated regions, with non-glaciated sites having lower amplification. Our models were developed using a combination of least-squares, mixed effects, and Bayesian techniques; the latter were used to show that predictor uncertainty did not appreciably affect the median model, but decreases estimates of dispersion. Our V_S30-scaling models are modular and additive to simulation-based models developed in complementary work that are applicable for conditions involving nonlinear site response.  

Behavior of Energy Piles in Soft Clays by Ismaail Ghaaowd    University of California San Diego

This study focuses on a novel approach to improve soft clays through in-situ heating to enhance the pullout capacity of offshore piles (suction caissons or torpedo piles) used to support floating structures. Research is needed to understand: the strategy for heat injection, the zone of influence of thermal, the time allotted before mechanical loads are applied, and the influence of thermal improvement on the pullout capacities of offshore piles for different loading directions. Although the time required for heating and thermal consolidation can be estimated using thermo-elastic analyses with heat flow due to conduction, the complexity involved in the coupled process indicates that these analyses need to be validated using experiments. This research approach involves a combination of heat transfer analysis, pore water pressure prediction, radial consolidation analysis, and centrifuge modeling of thermal effects on the pullout capacity of offshore piles.

Large-Scale Shake Table Testing with Saturated Sands: Experimental Observations  by Ahmed Ebeido University of California San Diego

Past earthquakes demonstrate that lateral spreading induced by liquefaction may cause excessive movement, and significant damage to structures and their underlying pile foundation. A large 16- ft laminar-container shaking table experiment was conducted to document pile response, due to the mechanism of liquefaction-induced lateral spreading. A single pile embedded in saturated soil was tested in a mildly inclined ground configuration. The pile was restraint above the soil surface. The ground stratum was built of sand in a multi-layered profile.  The experimental setup, test procedures will be described in detail. Results will be discussed to track the pile and soil lateral behavior.

Grace Parker is a PhD Candidate in Civil and Environmental Engineering advised by Dr. Johnathan Stewart at the University of California, Los Angeles. Her research focuses on engineering seismology, including ground motion modeling and site characterization. More specifically, she has worked as a part of the Pacific Earthquake Engineering Research Center (PEER) Next-Generation Attenuation (NGA) East Project on site condition proxies and empirical site amplification, and as part of the PEER NGA-Subduction Project on ground motion models for global subduction zones. She holds a bachelor's degree in Applied Geophysics from the University of California, Los Angeles. Grace has won many awards including the Seismological Society of America Annual Meeting student presentation award in 2017, the Martin Rubin Scholarship and award for academic excellence in 2016 and Dirty Bruin Award, UCLA Geotechnical Engineering outstanding first year graduate student in 2016.

Ismaail Ghaaowd is a PhD Candidate at the University of California, San Diego Department of Structural Engineering. He is also the student chapter president of ASCE Geo-Institute, UC San Diego representative to the G-I student leadership council, and Small Grant Committe Chair for 2018/2019. His main research area is the thermal soil improvement of soft clays, and his research involves centrifuge testing, triaxial testing, and analytical modeling. His research has focused on large-scale tests to study the shearing properties of tire derived aggregates. He holds bachelor and master of sciences degrees in Civil Engineering from Tripoli University in Libya and was a teaching assistant at Tripoli University from 2005 to 2008. He has also worked as the executive manager of a geotechnical consulting firm in Libya from 2008 to 2013 where he designed and supervised major geotechnical and civil engineering projects.

Ahmed Ebeido is a PhD Candidate in the Department of Structural Engineering at the University of California, San Diego advised by Prof. Ahmed Elgamal. His research focuses on lateral spreading and liquefaction effects on pile foundations. His research interests include geotehcnical earthquake engineering, soil-structure interaction and foundation engineering. He received his bachelor of science degree in 2012 where he graduated at the top of his class, with distinction and honors. In 2014, he graduated with his maters of science degree in structural engineering from Alexandria Univeristy  with a thesis titled "The effect of pile spacing on group behavior." He recieved a departmental fellowship for his research at UC San Diego in 2014. He has also worked for a structural engineering consulting firm and a geotechnical and marine design firm.

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