Seismic Hazard Curves for the Probability of Liquefaction: Fid-Bau Portal

Seismic Hazard Curves for the Probability of Liquefaction

Ulmer, Kristin J. / Franke, Kevin W. / Peterson, Brian D.

Seismically induced soil liquefaction is a significant seismic hazard that has caused substantial damage to foundations and other aspects of infrastructure in past earthquakes. The risk of soil liquefaction and subsequent unsatisfactory foundation performance often leads to the installation of remedial ground improvement, usually at significant cost to the project. While the majority of engineering practitioners use empirical triggering models to evaluate liquefaction initiation hazard, there is typically substantial uncertainty associated with these types of approaches. Performance-based earthquake engineering (PBEE) design methods have recently been introduced that will allow engineers to directly account for this uncertainty and express liquefaction triggering potential in seismic hazard curves for factor of safety against liquefaction. However, many engineering practitioners are choosing to move away from subjective factor of safety metrics. Although PBEE liquefaction assessment methods already incorporate the probability of liquefaction into the development of factor of safety hazard curves, these engineers would prefer the development of probability of liquefaction hazard curves. This paper derives a simplified approach for obtaining such hazard curves directly from factor of safety or N_req hazard curves for two popular probabilistic liquefaction triggering models. Such an approach allows engineers to easily switch between factor of safety and/or probability of liquefaction metrics. An example case study is demonstrated with the two probabilistic liquefaction approaches. The potential for probability of liquefaction to be incorporated into the performance-based assessment of certain liquefaction effects is briefly discussed.