STV Group (Czechia)

ASCE 7 requires site response analysis (SRA) for Site Class F locations due to the potential for seismic-induced soil failure, which is not adequately captured by code-based amplification factors. This study presents two such projects in the New Madrid Seismic Zone (NMSZ), where loose, saturated, granular soils are susceptible to liquefaction and strong ground shaking is expected. One-dimensional, total stress SRAs were conducted using both equivalent linear and nonlinear methods to evaluate ground motion amplification and soil behavior. The study highlights the challenges of modeling liquefiable soils in high seismic hazard zones, including uncertainties in site characterization, ground motion selection, and capturing the nonlinear response of loose soils undergoing large shear strains. Emphasis is placed on understanding model limitations and the uncertainties involved, with the goal of developing realistic ground motion estimates. The findings offer practical insights to guide seismic design in complex soil conditions where traditional approaches may fall short.