PSI - Issue 65

I. Shardakov et al. / Procedia Structural Integrity 65 (2024) 233–240 235 I. Shardakov, R. Tsvetkov, I. Glot, A. Shestakov, G. Gusev, V. Yepin / Structural Integrity Procedia 00 (2024) 000–000 3

using two independent boards. Software synchronization of the registration of AE signals coming from various sensors was carried out by recording a binary code sequence into the signal.

a

b

loading device

sensors

Fig. 1. (a) Model reinforced concrete structure placed on the test stand; (b) symmetrical fragment of the model structure with the layout of AE sensors and the location of the force load.

AE sensors were located along the crossbars and slab of the 2nd floor, as shown in Figure 1b. The distance from the jack to the sensors was different. Preliminary numerical simulation within the framework of elastic-plasticity theory showed that with a sufficient magnitude of force, areas of inelastic deformation of the floor slabs should appear in the vicinity of the jack. Therefore, the generation of AE signals will primarily be carried out in the vicinity of the place where the localized load is applied. The sensor placement scheme chosen in this way makes it possible to compare the parameters of AE signals occurring at different distances from the source location. The distance from the jack to sensors 1 and 2 was 0.2 m, the distance to sensors 3 and 4 was 1.8 m and 3.8 m, respectively. After each loading stage, unloading was carried out. At each subsequent stage, the maximum load value was greater than the previous one, and the load increase was no more than 10 kN. A total of 38 cycles were implemented. The load at the last loading step reached 150 kN. Figure 2 shows the time dependence of the magnitude of the local normal force acting on the floor slab, experimentally measured by a force sensor, in accordance with Figure 1b.

0 50 100 150

Force, kN

5000

10000

15000

20000

25000

Time, s

Fig. 2. Time dependence of external localized force in successive cycles of loading - complete unloading.