Probabilistic Seismic Hazard Analysis for Maximum Seismic Shear Stresses in Soils Using Improved Ground-Motion Parameters.

Maximum seismic shear stresses () have been recognized as one of the important parameters in design practice. This study develops ground-motion parameters for and implements these in probabilistic seismic hazard analysis to provide the distribution of deep soil layers for design purposes. The application of improved ground-motion parameters for is demonstrated at the Oakland International Airport, where a thick Young Bay Mud deposit exists under the artificial fill. Model biases in the predictive equations of seismic shear-stress reduction coefficients () are evaluated by comparison with the site response analyses performed with a wide range of input ground motions. Based on these results, we introduce improved ground-motion parameters for as a linear combination of spectral accelerations, implemented in probabilistic seismic hazard analysis to calculate seismic hazard curves. Conditional mean spectra are calculated, given at 10% in 50 years to illustrate the variations in frequency contents with depth compared with the uniform hazard spectra. Finally, is calculated with depth by using hazard values of and compared with the peak-ground-acceleration-based and uniform-hazard-spectra-based calculations. Analysis results show that will be underestimated for deep soil layers by peak-ground-acceleration-based calculation if the median value of is used in design practice. [ABSTRACT FROM AUTHOR]