Geotechnical Engineering Distinguished Seminar Series
The Geotechnical Engineering Program brings acclaimed speakers to campus to discuss current advancements in geotechnical engineering.
Foundation Performance of Millennium Tower in San Francisco, California
Jonathan Stewart, Ph.D., P.E., NAE
Professor, University of California Los Angeles
Samueli School of Engineering, UCLA
Friday, Oct. 17, 2025
Noon to 1:30 p.m.
Earthquake Engineering Lab Auditorium
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Seminar abstract: The Millennium Tower is a 58-story reinforced concrete building that was constructed in San Francisco, California between 2005 and 2009. The tower is founded on an embedded, pile-supported mat with pile tips bearing in dense marine deposits that overlie an over-consolidated marine clay layer known locally as Old Bay Clay. This clay layer experienced stress increases from tower’s self-weight and from multiple episodes of de-watering between 2006 and 2018 at the tower site and neighboring sites. Settlements of the tower foundation have been measured since 2006 and lateral deflections of the tower have been inferred and measured since 2009. Available information on this case history includes geotechnical site conditions and data from a monitoring program that tracked foundation settlements, tower tilt, groundwater levels at the tower site and ground inclinations over time. This presentation will present the case history and its significance, discuss the ground deformation mechanisms that caused the observed movements, describe the degree to which the movements can be predicted and discuss lessons from this case history for the design of deep foundations for tall buildings in San Francisco and geologically similar regions.
About the speaker: Jonathan P. Stewart’s technical expertise is in geotechnical engineering, earthquake engineering and seismology. He works on problems related to hazard characterization (ground motion, ground failure) and infrastructure response to those hazards (soil-structure systems, distributed infrastructure systems). He has held leadership positions at the University of California, Los Angeles (department chair); American Society of Civil Engineers (committee chair, journal editor); the Earthquake Engineering Research Institute (board of directors, journal editor); as well as federal and state panels and committees related to seismic risk. He is an elected member of the National Academy of Engineering.
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