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Selecting Analytic Tools for Concrete Dams Address Key Events Along Potential Failure Mode Paths

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In this document, failure is considered the uncontrolled release of the reservoir. However, this may or may not always be the case given the purpose or hazard of a structure or given an agency’s requirements for a structure. How do we determine if a concrete dam can fail? Failure results from sequences of events that must follow one upon another. Because a dam cannot fail without the full chain of events, conclusively ruling out any event justifies concluding that the dam will not fail. This document introduces event trees. Event trees are pictorial representations of the sequences of events (called nodes) leading to failure. The possibility of each node occurring is evaluated by analyses. It is the experience of the authors that engineers often rush to analysis without consideration of the failure process. As a result, expensive analyses are done that are not needed, waste time, and often do not answer the question of whether a dam will fail. Examples presented are for instructional purposes only. Assumptions made, material properties used, and loadings were selected to illustrate structural analysis methods and failure modes, and are not generally applicable.

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Icon for file of type application/pdfSelecting Analytic Tools for Concrete Dams Address Key Events Along Potential Failure Mode Paths (FEMA P-1016)

The purpose of this document is to stress the importance of understanding the sequences of events leading to failure of concrete dams and selecting analysis methods that address these specific events. The selected analysis method may range from straightforward to complex, depending on the potential failure mode being analyzed. It is stressed that a less complex analysis with less uncertainty is the preferred strategy. Included in this report and the appendices are examples of this process. These examples are not intended to be a complete listing of concrete dam potential failure modes. Each dam is unique and has its own issues; therefore, it is important for the engineer to understand the potential failure modes and sequences of events that enable them.

5.74MJuly 1, 2014