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Intensity Measures (2010-2013)

NEESR-CR: Evolutionary Intensity Measures for More Accurate and Informative Liquefaction Hazard Evaluation

Principal Investigator: Steve Kramer (University of Washington)

Co-Principal Investigators: Kenan Hazirbaba (University of Alaska, Fairbanks) Matthew Kuhn (University of Portland)

This study is intended to investigate the relative abilities of different earthquake intensity measures to predict the initiation and resulting effects of liquefaction. To accomplish this we will use centrifuge testing to systematically investigate liquefaction under transient loading conditions. We will create a series of four models, each composed of saturated sand. The four models will have layers of varying density, and will be tested under level ground conditions and then tested again while slightly inclined to simulate sloping ground conditions.

Each of these models will be placed in the centrifuge, and once they have attained the appropriate gravitational force, each will be subject to a suite of 24 transient motions. Each motion is unique with respect to its amplitude, duration and frequency content, and has been carefully selected for its ability to distinguish between the predictive capabilities of different candidate intensity measures. All 24 of these input motions will be scaled down to generate relatively low pore pressures. Once a single motion has been applied to our model and data has been recorded, all excess pore pressure will be allowed to dissipate prior to the application of the next motion. Once the specimen has been subject to the 24 motions at the initial scaling level, they will be applied again at a higher scaling level. After these suites of motions have been applied and the subsequent recordings documented the model will be tilted at a 2o angle and the process repeated.

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