Issue 61

M.E. Kerkar et alii, Frattura ed Integrità Strutturale, 61 (2022) 530-544; DOI: 10.3221/IGF-ESIS.61.36

the Teton Dam (USA) in 1976, significant progress has been made and society continues to increase its demands for safety, reliability of critical infrastructure, design, construction and operation of dams should be integrated into the risk management framework where dam safety is not only a federal, state or local issue, it can affect people and property across locations, state and even national borders [15, 16]. Concrete gravity dams are usually built from many monoliths, when a concrete gravity dam fails, one or more monoliths are washed away [17].

S TRUCTURAL RELIABILITY

T

he reliability of an engineering system can be defined as the ability to fulfil its design purpose for a specified period of time. This ability can be measured using the probabilistic theory that it will perform the function for which it was designed under given conditions and for a given duration. Structural reliability is formulated in terms of a vector of structural system random variables, X = {X 1 , X 2 , ..., X n }, where {X 1 , X 2 , ..., X n } are the basic random variables which can describe loads, structural system dimensions, materials and these characteristics and properties of the cross-section [18, 19]. A limit state function, g (X) = 0 describes the operation of the system in terms of the basic random variables X, where S is the strength of the material making up the structure and L is the stresses (loads) exerted on the structure [20]. The safety margin M and the limit state function g can be written in the general form:

(4)

g(X) g( )   M S, L

When we place ourselves in the physical space, the space formed by S and L , we notice that the limit state function allows us to divide the physical space into three domains (Fig. 6):

 g ( S, L ) < 0: failure domain;

 g ( S, L ) = 0: limit state;

 g ( S, L ) > 0: safety range.

Figure 6: Failure domain, limit state and safety range. An analysis space can be defined for concrete dams based on two vectors; structural reliability models (X-axis) and deterministic models (Y-axis), as shown in Fig. 7.

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