Project:  Characterization of Strong Ground Motion

PI(s):  Steve Kramer

Sponsor:  NSF, University of Washington

Objective:  This project is intended to identify strong ground motion parameters that provide improved correlation to the seismic performance of geotechnical systems. In current practice, ground motions are most commonly characterized using amplitude parameters such as peak acceleration or spectral acceleration(s). Such parameters typically provide information about the ground motion that is most useful in a particular frequency band, but which may not correlate well to actual performance.

Research Approach:  We assume that the most useful ground motion parameters must be defined on a problem-specific basis, and are focusing on two important problems in geotechnical earthquake engineering. The first is prediction of permanent displacements of slopes in non-liquefiable soils. For such slopes, permanent displacements are most commonly predicted using Newmark (sliding block) analyses. We have performed Newmark analyses for 1492 recorded and synthetic ground motions that cover a wide range of source parameters (magnitude, distance, style of faulting) and site conditions. We have also computed 79 different strong motion parameter values for each of these motions. Statistical analysis of the correlation between the ground motion parameters and the predicted displacements have been used to identify an optimum parameter, i.e. a parameter that correlates well with predicted displacements). An attenuation relationship for this parameter will be developed and used in a probabilistic seismic hazard analysis to produce improved regional estimates of seismic slope stability hazards. This process will be repeated for lateral spreading displacements.

For more information send E-Mail to: kramer@u.washington.edu