PSI - Issue 28

G.N. Gusev et al. / Procedia Structural Integrity 28 (2020) 2328–2334 Gusev G.N., Shardakov I.N/ Structural Integrity Procedia 00 (2019) 000–000

2333

6

Number

Type of work

Dwell time

of stages

1 2 3 4 5 6 7 8

Filling the tank to 50% of its capacity and inspection Filling the tank to 75% of its capacity and inspection Filling the tank to 90% of its capacity and inspection Filling the tank to its maximum capacity

1 hour 2 hours 3 hours 24 hours

Emptying the tank to 90% of its capacity and generating the overpressure greater than the design pressure by 25 % Emptying the tank to 50% of its capacity and inspection Emptying the tank to 10…15% of its capacity and inspection

30 minutes

— — —

Complete emptying the tank and inspection

Fig. 5. Graphical plot showing changes in stresses at the examined points and changes in water level over time in buckling zone (zone 3) and at lower height. 4. Results After gathering and analyzing the results of the experimental study, the following conclusions can be drawn:  Throughout the experiment, no critical strain value specified in normative and design documents was exceeded in any structural element (joint), which agrees well with the calculated results. The results of mathematical modeling (second stage) performed taking into account the characteristics of defects correlated with the in-situ measurements taken at all examined points.  Correlation of the water level in the tank with the level of deformations at points along the shell height is traced. The results are consistent with the mathematical simulation data determined for the design version of the tank.  The values of deformation at the very beginning of measurements and at their end differ within the measurement error. No strain accumulation was observed at all 32 measurement points. The tank returned to its original state, which was confirmed by calculations.  The safety factor of the completely filled tank varied, according to the test schedule, within 7% to 50%. It is worth noting that the safety factor less than 10% (Fig.5) was detected only for one joint of zone 3.