Jonathan D. Bray

Jonathan D. Bray, Ph.D., P.E., NAE

Faculty Chair in Earthquake Engineering Excellence

Professor Bray has supervised the research of 35 Ph.D. students. Much of this research was in response to issues raised following major earthquakes. For example, the Bray and Sancio (2006) liquefaction of fine-grained soil criteria followed observations of silt liquefaction in the 1999 Kocaeli, Turkey earthquake (Bray et al. 2004). The simplified seismic slope displacement procedures of Bray and Travasarou (2007, 2009) were calibrated to provide results consistent with post-earthquake field measurements of earth dams and municipal solid waste (MSW) landfills. Damage observed during the 1994 Northridge earthquake motivated studies of the engineering properties of MSW with insights on its shear strength by Bray et al. (2009). The devastating effects of near-fault, pulse ground motions due to forward-directivity led to characterization schemes developed by Bray et al. (2009) and Hayden et al. (2014). Geotechnical mitigation measures proposed in Oettle and Bray (2013) are well-founded by observations of the effects of surface fault rupture following several important earthquakes. Lastly, recent studies documenting and discerning lessons from the effects of soil liquefaction on office buildings in Christchurch, New Zealand (e.g., Bray et al. 2014, 2017) have provided key insights on the important roles of the CPT and cyclic laboratory testing to characterize soil deposits and on the use of dynamic soil-structure-interaction (SSI) effective stress analyses to evaluate shear-induced liquefaction building settlement. A simplified procedure for evaluating liquefaction-induced building settlement is proposed in his 2017 Ishihara Lecture.

Significant research thrusts also utilize advanced geotechnical centrifuge modeling and advanced numerical tools such as discrete element modeling (DEM). The Dashti et al. (2010a,b) centrifuge experiments identified and evaluated the relative importance of key shear-induced and volumetric-induced liquefaction mechanisms. Mason et al. (2013), Trombetta et al. (2014), and Hayden et al. (2015) explored key dynamic SSI responses of structures founded on non-liquefiable and liquefiable ground. O’Sullivan et al. (2002, 2003a,b, 2004) emphasized the need to utilize realistic 3D sphere-cluster particles to capture the response of granular media. Work is continuing with Ph.D. Candidate Qian who is utilizing a parallel-computing to evaluate the stress-dependent response of cemented sand that involves particle crushing.  

RESEARCH PROJECTS

"Assessment of the Performance of the Ground and Facilities at Wellington Port during Three Earthquakes,” National Science Foundation, 04/20-03/23, $480,382; Principal Investigator.

“Performance Based Earthquake Engineering Assessment Tool for Gas Storage and Transmission System,” California Energy Commission, 12/19-03/22, $4,940,158; Principal Investigator.

“Detailed Evaluation of Insightful Liquefaction Ejecta Case Histories,” U.S. Geological Survey, National Earthquake Hazards Reduction Program, 06/20-05/21, $96,974; Principal Investigator.

“Liquefaction-Induced Ground Settlement Procedure,” State of California, Department of Transportation (Caltrans), 10/21-9/22, $65,000; Principal Investigator.

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CPT CASE HISTORIES OF POST-LIQUEFACTION FREE-FIELD GROUND SETTLEMENT

Franklin Olaya and Professor Jonathan D. Bray developed a CPT-based post-liquefaction free-field ground settlement case history database described in the report provided below with the flatfile which is also provided below (other appendices are available through links below and in the report):

Olaya, F.R. and Bray, J.D. (2022) "CPT Case Histories of Post-Liquefaction Free-Field Ground Settlement," Report No. UCB/GT 2022-02, July 11, 2022.

Case Histories Summary Flatfile - Appendix A

CPT Data - Appendix B

Case Histories - Appendices C - I

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Detailed Evaluation of Insightful Liquefaction Ejecta Case Histories for the Canterbury Earthquake Sequence, New Zealand

Zorana Mijic and Professor Jonathan D. Bray in collaboration with Dr. Sjoerd van Ballegooy developed an liquefaction ejecta database described in the report provided below with two electronic appendices which are also provide below:

Zorana, M., Bray, J.D., and van Ballegooy (2021) “Detailed Evaluation of Insightful Liquefaction Ejecta Case Histories for the Canterbury Earthquake Sequence, New Zealand," Final Technical Report, U.S.G.S. Award Number: G20AP00079, August 31, 2021.

Detailed Ejecta Case Histories - Appendix A (large PDF file that documents each case history)

Detailed Ejecta Case Histories Summary Flatfile - Appendix B

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Simplified Procedure for Estimating Liquefaction-Induced Building Settlement

Professor Jonathan D. Bray in collaboration with Dr. Jorge Macedo developed a simplified procedure for estimating liquefaction-induced building settlement. The procedure is described in this paper:

Bray, J.D. and Macedo, J. (2017) “6th Ishihara Lecture: Simplified Procedure for Estimating Liquefaction-Induced Building Settlement,” Soil Dynamics and Earthquake Engineering J., V 102, 215-231, https://doi.org/10.1016/j.soildyn.2017.08.026.


This procedure includes a method for estimating Shear-Induced Liquefaction Building Settlement. It is implemented in the program CLiq v.2.0 (https://geologismiki.gr/products/cliq/). A spreadsheet for performing this calculation is also provided below:

Bray & Macedo (2017) Shear-Induced Liquefaction Building Settlement

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Simplified Seismic Slope Displacement Procedures

Professor Jonathan D. Bray in collaboration with Dr. Jorge Macedo and Dr. Thaleia Travasarou developed simplified procedures for evaluating the seismic slope stability of earth/waste structure and natural slopes. The procedures are described in these papers:

Bray, J.D. and Travasarou, T. (2007) “Simplified Procedure for Estimating Earthquake-Induced Deviatoric Slope Displacements,” J. of Geotech. & Geoenv. Engrg., ASCE, Vol. 133(4), 381-392.

Bray, J.D. and Travasarou, T. (2009) “Pseudostatic Coefficient for Use in Simplified Seismic Slope Stability Evaluation,” J. of Geotechnical and Geoenv. Engineering, ASCE, 135(9), 1336-1340.

Bray, J.D., Macedo, J., and Travasarou, T. (2018) “Simplified Procedure for Estimating Seismic Slope Displacements for Subduction Zone Earthquakes,” J. of Geotechnical and Geoenvironmental Engineering, ASCE, V. 144(3): 04017124, DOI: 10.1061/(ASCE)GT.1943-5606.0001833.

Bray, J.D., and Macedo, J. (2019) “Procedure for Estimating Shear-Induced Seismic Slope Displacement for Shallow Crustal Earthquakes,” J. of Geotechnical and Geoenvironmental Engineering, ASCE, V. 145(12), doi: 10.1061/(ASCE)GT.1943-5606.0002143.

The most recent procedures (e.g., Bray et al. 2018, and Bray and Macedo 2019) are provided in this Simplified Seismic Slope Stability Excel Spreadsheet:

B&M19_BMT18-Seismic-Slope-Displacement

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Oso Landslide State of Washington Reports

 

Rogers, J.D., Pyles, M.R., Bray, J.D., Skaugset, A., and Storesund, R. (2015) “Preliminary Expert Report, Superior Court of Washington for King County,” No. 14-2-18401-8 SEA, June 1.

 

Rogers, J.D., Pyles, M.R., Bray, J.D., Skaugset, A., Storesund, R., and Schlieder, G. (2016) “Interim Expert Report, Superior Court of Washington for King County,” No. 14-2-18401-8 SEA, January 22.

 

Pyles, M.R., Rogers, J.D., Bray, J.D., Skaugset, A., Storesund, R., and Schlieder, G. (2016) “Expert Opinion Report, Superior Court of Washington for King County,” No. 14-2-18401-8 SEA, June 30.

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Liquefaction Sediment Ejecta Estimates

The Ejecta Potential Index (EPI) captures key aspects of the hydraulic processes of liquefaction manifestation. Its use is described in Hutabarat, D., and Bray J.D. (2021) “Seismic Response Characteristics of Liquefiable Sites with and without Sediment Ejecta Manifestation,” J. of Geotechnical and Geoenvironmental Engineering, ASCE, 10.1061/(ASCE)GT.1943-5606.0002506, in press.

Supporting files for the Hutabarat & Bray (2021) paper are provided below:

Animations (uploaded at ASCE JGGE site with paper)

CPT Back-Analyses

Sensitivity Results - Layer Stratification

Sensitivity Results - Ground Motion

Sensitivity Results - Groundwater Level

Sensitivity Results - Hydraulic Conductivity

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Modified-UBCSAND User-Defined Model

This model was developed at UC Berkeley by Dr. Nicolas K. Oettle in collaboration with Professor Jonathan D. Bray. The models are based on UBCSAND developed by Professor Peter Byrnes, Michael Beaty, et al. Documentation of UBCSAND can be found on the FLAC website. The modifications to the UBCSAND model for use in surface fault rupture interaction analysis can be found in these papers:

Oettle, N, and Bray, J.D., “Fault Rupture Propagation through Previously Ruptured Soil,” JGGE, ASCE, Vol. 139(10), 2013, pp. 1637-1647.

Oettle, N, and Bray, J.D., “Geotechnical Mitigation Strategies for Earthquake Surface Fault Rupture,” JGGE, ASCE, Vol. 139(11), 2013, pp. 1864-1874.

Modified-UBCSAND Model:

FLAC6 DLL for modUBCSAND

FLAC7 DLL for modUBCSAND