EFFECTS OF RELATIVE DENSITY AND PULSE DURATION ON DYNAMIC RESPONSE OF FOOTINGS BURIED IN SAND.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS
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A series of dynamic tests on square footings buried in sand was conducted to determine the effect of varying relative density. It was found that a 60 percent increase in the stiffness of the load-displacement relation resulted from increasing relative density from 70 to 90 percent. In addition, it was determined that a dimensionless maximum load parameter-maximum displacement parameter relation developed in an earlier study involving tests at a single relative density was valid for the 70 to 90 percent relative density range. A second series of dynamic tests on square footings buried in sand was conducted to determine the influence of the duration of the dynamic load pulse. From this series of tests it was concluded that for peak dynamic loads of about one-half the static bearing capacity, pulse duration has a negligible influence on response. However, for loads slightly in excess of static bearing capacity, maximum displacement and the time to its occurrence increase with pulse duration. For each dynamic test in the relative density study, plots of computed column load, load column acceleration, footing load or reaction, and footing displacement versus time were drawn and are presented as an appendix. Author
- Structural Engineering and Building Technology