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|Title:||Vibration test of Richard B. Russell Concrete Dam after reservoir impoundment|
|Authors:||United States. Army. Corps of Engineers. Savannah District.|
Bevins, Tommy L.
Chiarito, Vincent P.
Hall, Robert L.
Forced vibration tests
Richard B. Russell Dam
|Publisher:||Structures Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; SL-88-14.|
Abstract: The Richard B. Russell Dam has recently been completed by the US Army Corps of Engineers approximately 170 miles from the mouth of the Savannah River between Georgia and South Carolina. The crest of the concrete gravity dam is 1,884 ft long and is composed of 13 nonoverflow, 8 intake, and 11 spillway monoliths, the tallest of which is approximately 200 feet high. To experimentally determine the dynamic properties of the dam with and without hydrodynamic interactions, forced vibration tests were conducted before and after reservoir impoundment. The average reservoir elevation during the test following reservoir impoundment was 470 feet. This is an increase of 127 feet above the upstream elevation during the first test. The structure was excited at three locations by a crest-mounted 17,000-lb inertial mass that was driven by an electrohydraulic servo-controlled actuator. The force input was computed as the product of the measured acceleration and the mass. Servo accelerometers with sensitivities ranging from 0.25 to 5.0 V/g were used to measure the horizontal motion of all 32 monoliths and the distributions of horizontal acceleration with elevation in the three drive-point monoliths. Dynamic pressures at the dam-reservoir interface were measured at the upstream face of the tallest nonoverflow monolith. Piezoelectric pressure transducers with a charge sensitivity of approximately 150 pC/psi measured the dynamic pressure. The results determine the dynamic parameters of the dam with hydrodynamic interactions. The natural frequencies, damping estimates, and mode shapes were determined. Comparisons with the first test before impoundment indicated: (A.) natural frequencies were reduced (approximately 10 percent for the fundamental frequency and 2 percent for the fifth mode), (B.) damping estimates were increased by approximately 0.4 percent of critical, and (C.) there was a reasonable agreement in the first three mode shapes between the two tests. The hydrodynamic pressures were of low magnitude but were in agreement with analytical predictions and earlier test results from forced vibration tests.
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