Seismic fragility assessment of concrete gravity dams

Abstract

SUMMARYMany concrete gravity dams have been in service for over 50 years, and over this period important advances in the methodologies for evaluation of natural phenomena hazards have caused the designbasis events for these dams to be revised upwards. Older existing dams may fail to meet revised safety criteria and structural rehabilitation to meet such criteria may be costly and di cult. Fragility assessment provides a tool for rational safety evaluation of existing facilities and decision-making by using a probabilistic framework to model sources of uncertainty that may impact dam performance. This paper presents a methodology for developing fragilities of concrete gravity dams to assess their performance against seismic hazards. The methodology is illustrated using the Bluestone Dam on the New River in West Virginia, which was designed in the late 1930s. The seismic fragility assessment indicated that sliding along the dam-foundation interface is likely if the dam were to be subjected to an earthquake with a magnitude of the maximum credible earthquake (MCE) speciÿed by the U.S. Army Corps of Engineers. Moreover, there will likely be tensile cracking at the neck of the dam at this level of seismic excitation. However, loss of control of the reservoir is unlikely.

A new class of seismic damage and performance indices for arch dams via ETA method

“…The evolution of joint movement (especially joint sliding), Fig. 10(a), resembles the cumulative distribution function commonly used in fragility functions [29]. Thus, one may propose an analytical expression for joint response under ETA.…”

Earthquake Damage Analysis of Concrete Gravity Dams: Modeling and Behavior under Near-Fault Seismic Excitations

“…In this research, the surface-based fluid-structure interaction approach [Abaqus, 2007] is utilized for the modeling of the dam-reservoir and foundation-reservoir interactions. On the other hand, the modeling of the dam-foundation interaction follows the contact surface approach [Abaqus, 2007;Tekie and Ellingwood, 2003]. With this approach, a surface-based contact pair is defined at the dam-foundation interface.…”

“…The surfaces come into contact when the interpenetration between them becomes zero. The contact interaction in the tangential direction is characterized by the Coulomb friction law [Abaqus, 2007;Tekie and Ellingwood, 2003], which is depicted in Fig.11b. With this law, at the contact interface, the tangential behavior is divided into two kinematic states, i.e., the sticking state and the slipping state.…”

Aging degradation of mechanical structures

“…The methodology is able to take into account the nature of past and future loads, and randomness in strength and in degradation results from environmental factors. A methodology was presented by Tekie and Ellingwood [2003] for developing fragilities of concrete gravity dams to assess their performance against seismic hazards. A robust system reliability evaluation method was proposed for ageing redundant structures by Wang et al [1997].…”