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|Title:||Fragility analysis of concrete gravity dams|
|Authors:||Georgia Institute of Technology. School of Civil and Environmental Engineering.|
United States. Army. Corps of Engineers. Baltimore District.
Black & Veatch.
Tekie, Paulos B.
Ellingwood, Bruce R.
|Keywords:||Bluestone Dam (W. Va.)|
Probabilistic safety analysis
|Publisher:||Information Technology Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||ERDC/ITL TR ; 02-6.|
Abstract: Concrete gravity dams are an important part of the nation's infrastructure. Many dams have been in service for over 50 years, during which time important advances in the methodologies for evaluation of natural phenomena hazards have caused the design-basis events to be revised upwards, in some cases significantly. Many existing dams fail to meet these revised safety criteria and structural rehabilitation to meet newly revised criteria may be costly and difficult. A probabilistic safety analysis (PSA) provides a rational safety assessment and decision-making tool managing the various sources of uncertainty that may impact dam performance. Fragility analysis, which depicts the uncertainty in the safety margin above specified hazard levels, is a fundamental tool in a PSA. This study presents a methodology for developing fragilities of concrete gravity dams to assess their performance against hydrologic and seismic hazards. Models of varying degree of complexity and sophistication were considered and compared. The methodology is illustrated using the Bluestone Dam on the New River in West Virginia, which was designed in the late 1930's. The hydrologic fragilities showed that the Bluestone Dam is unlikely to become unstable at the revised probable maximum flood (PMF), but it is likely that there will be significant cracking at the heel of the dam. On the other hand, the seismic fragility analysis indicated that sliding is likely, if the dam were to be subjected to a maximum credible earthquake (MCE). Moreover, there will likely be tensile cracking at the neck of the dam at this level of seismic excitation. Probabilities of relatively severe limit states appear to be only marginally affected by extremely rare events (e.g. the PMF and MCE). Moreover, the risks posed by the extreme floods and earthquakes were not balanced for the Bluestone Dam, with seismic hazard posing a relatively higher risk. Limit state probabilities associated with postulated states of structural damage are larger than the "de minimis" risk acceptable to society, and further investigation involving benefit-cost analyses to assess the risk posed by the Bluestone Dam appears warranted. NOTE: This file is large. Allow your browser several minutes to download the file.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|
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|ERDC-ITL-TR-02-6.pdf||30.88 MB||Adobe PDF|