Conventional “pseudo-probabilistic” procedures to evaluate liquefaction triggering and its effects have been shown through recent research to produce estimates of liquefaction factor of safety at inconsistent and often unacceptable levels of risk. These errors are introduced through the incorrect assumption that using probabilistic ground motions in a deterministic liquefaction analysis will yield a probabilistic estimate of liquefaction factor of safety. The inconsistent consideration of liquefaction risk could contribute to undesirable performance or even collapse of various important structures such as bridges or retaining walls in the event of an earthquake. Conversely, the inconsistent consideration of liquefaction risk could also potentially contribute to the unnecessary and expensive over-design of liquefaction mitigation alternatives. Utilization of a fully-probabilistic or performance-based liquefaction triggering procedure, which considers both uncertainty in the seismic loading and the liquefaction triggering relationship, could effectively solve these problems. Furthermore, probabilistic evaluation of liquefaction triggering could potentially be taken into account when considering liquefaction effects such as lateral spreading or free-field liquefaction settlements. However, current performance-based liquefaction procedures (e.g. Kramer & Mayfield 2007) are quite complex and beyond the level of practical application for most practicing engineers. Additionally, available performance-based methods generally focus on using the standard penetration test (SPT). Increasingly, the cone penetration test (CPT) is becoming a preferred instrument for performing in-situ assessment of liquefaction hazard. Development of code-compatible simplified approximations of performance-based analysis methods for the CPT to assess liquefaction triggering and its effects could be a viable solution to overcome these challenges.

1. Develop performance-based procedures for the CPT modeled after recent performance-based procedures for the SPT to compute the hazard from liquefaction triggering, lateral spread displacement, and post-liquefaction free-field settlement at select return periods (475, 1033, and 2475 years). 2. Develop simplified performance-based procedures for the CPT modeled after recent simplified performance-based procedures for the SPT [TPF-5(296)] to closely approximate the performance-based analysis results for liquefaction triggering, lateral spread displacement, and post-liquefaction free-field settlement at select return periods (475, 1033, and 2475 years). 3. Develop liquefaction triggering, lateral spread displacement, and post-liquefaction reference parameter maps in GIS format at return periods of 475 years, 1033 years, and 2475 years for each of the states participating in the study.

Tasks for this study include, regarding the participating states: 1. Develop full performance-based liquefaction triggering procedure 2. Develop full performance-based lateral spread procedure 3. Develop full performance-based post-liquefaction, free-field settlement procedure 4. Develop a numerical tool that will allow the calculation of performance-based liquefaction triggering, post-liquefaction settlement, and lateral spread displacement 5. Derivation and validation of a new simplified liquefaction triggering procedure 6. Derivation and validation of a new simplified lateral spread displacement procedure 7. Derivation and validation of simplified post-liquefaction free-field settlement procedure 8. Development of liquefaction reference parameter maps 9. Comparison of simplified, conventional (AASHTO), and deterministic analysis methods 10. Development of a simplified design procedure that incorporates both performance-based and conventional methods 11. Preparation of the Annual and Final Reports 12. Dissemination of Results 13. Technical Advisory Committee (TAC) Meetings

The Principal Investigator for this study will be Dr. Kevin Franke of Brigham Young University. Dr. Franke has extensive experience with developing performance-based models to evaluate liquefaction and its effects. He has been the Principal Investigator/Co-Principal Investigator on previous performance-based liquefaction studies for the US Geological Survey and the NSF. His qualifications for this study are based on nearly 11 years of experience with performance-based and probabilistic design methods. Work is planned to begin in early 2016 and will run through 2020. At least one face-to-face meeting in Utah is anticipated with the project partners during the study, with travel costs covered by the project funds. The minimum partner commitment expected is $44,000, consisting of $22,000 for FY 2016 and $22,000 for FY 2017.