Issue 57

A. Aliche et alii, Frattura ed Integrità Strutturale, 57 (2021) 93-113; DOI: 10.3221/IGF-ESIS.57.09

To ensure the accuracy of the estimation of the probability of failure obtained with Monte Carlo simulations, convergence tests were performed for different limit state functions as shown in Fig.10.These results show that the convergence and the stability of estimation of P f value are obtained from a number of simulations equal to 4.10 5 . Therefore, the number 5.10 5 is used to generate Monte Carlo samples.

0,35

0,25

0,15

P f

Overturning Compression stress Sloshing

0.05

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 x 10 5 0

N sim

Figure 10: Convergence and stability of probability of failure P f with respect to the number of simulations.

Evolution of the failure probability regarding to the water height in the container Figs. 11 to 13 show the evolution of the failure probability for the following failure modes: overturning, compression stress and sloshing, as a function to the water height in the tank and the different seismic zones.

-3

Overturning

x 10

3.5

Zone I Zone IIa Zone IIb Zone III

3

2.5

2

P f

1.5

1

0.5

0

0

1

2

3

4

5

6

7

8

He (m)

Figure 11: Failure probability as a function of water height in the overturning failure mode.

The failure probability is very small (< 10 -8 ) for sliding and traction failure mode regarding the water height in the tank container and the seismic zone, thus it can be considered insignificant. However, Fig. 13 shows that the failure probability of the sloshing failure mode is insignificant, except when the water height approaches the level of the overflow (about 50 cm). In other words, the sloshing failure mode appears when the water height in the tank is at its maximum level. Moreover, this situation leads to a high failure probability for the high and very high seismic zones, where the probability of failure exceeds the admissible values for a civil engineering structure, which should be lower than the admissible value of 10 -3 [26]. For compression stress and overturning failure modes, the failure probability increases with respect to the water height and the seismic zone. Tab. 5 gives the maximum values of the failure probability P f-max regarding of the seismic zone and for a water height equal to 50% of H max . These results demonstrate

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