PSI - Issue 64

Abbas S.A. Al-Hedad et al. / Procedia Structural Integrity 64 (2024) 1386–1393 Abbas S. A. Al-Hedad and Muhammad N. S. Hadi / Structural Integrity Procedia 00 (2019) 000 – 000

1392

7

(1)

is the accumulative number of load cycles of n stress levels up to failure of Specimens UC, GC and

where 2GC,

is the number of load cycles at the stress level i ,

is the maximum cyclic load at the stress level i ,

is the average failure load of plain concrete beam specimens tested under static loads. From Fig. 7(a), it can be seen that the geogrid prolonged the fatigue life of Specimens GC and 2GC in comparison with Specimens UC. The geogrid increased the fatigue life of Specimens GC by about 44% more than the fatigue life of Specimens UC. In addition, Specimens 2GC (reinforced with two layers of geogrid) exhibited a significant improvement in the fatigue behavior by about 6.5 times more than the fatigue life of Specimens GC and by about 11.6 times more than the fatigue life of Specimens UC. Figure 7(b) shows the fracture energy of Specimens UC, GC and 2GC up to failure. The fracture energy of Specimens UC, GC and 2GC was calculated by multiplying the maximum cyclic load at each flexural stress level by the width of crack measured at the tip of the notch of the specimens. Figure 10 shows that Specimens GC (reinforced with one layer of geogrid) did not exhibit a clear resistance of the cyclic loads in comparison with Specimens UC (control specimens). While the fracture energy of Specimens 2GC (reinforced with two layers of geogrid) was significantly higher than that of Specimens UC (Fig. 7(b)). The increase of the average fracture energy of Specimens 2GC was about 86% more than the average fracture energy of Specimens UC. The maximum cyclic loads with the average width of crack at the tip of Specimens UC, GC and 2GC are shown in Fig. 8. In general, Specimens GC and 2GC failed at the maximum cyclic loads higher than the maximum cyclic loads of Specimens UC. The increase in the average maximum cyclic loads was 8% for Specimens GC and 18% for Specimens 2GC compared with the average maximum cyclic loads of Specimens UC. The average width of crack at the tip of the notch of Specimens 2GC significantly increased by about 90% in comparison with the average width of crack of Specimens UC and GC (Fig. 8). It can be mentioned that the geogrid reinforced concrete specimens significantly remained able to resist the cyclic loads in spite of a crack was being visible.

(a)

(b)

Fig. 7. The fracture energy of Specimens UC, GC and 2GC up to failure; (a) Fatigue life of Group CY specimens to failure, and (b) Fracture energy of the specimens of Group CY to failure.

Fig. 8. Maximum cyclic loads and the width of crack at failure of Group CY specimens.