Toward Improving Damping Characterization for Site Response Analysis

Accurately constraining site response analysis (SRA) results and their associated uncertainty is a key aspect of the seismic design process. The variability and uncertainty in SRA results are typically attributed to the uncertainties in the dynamic properties of the materials, the selected input motions, and intrinsic model assumptions. This study focuses on the impact of damping on site response and explores ways to improve the compatibility of laboratory damping measures with the observed attenuation in the field. Sixteen recording stations from the KiK-net database are used as case studies to compare theoretical transfer functions using different damping models with the corresponding empirical transfer functions. Results from this study support recent research efforts that highlight how geotechnical damping models provide a lower estimate of damping than what is observed in the field, primarily because only material damping can be captured when testing small-scale soil samples in the laboratory.