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

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increase of the number of geogrid layers significantly leads to improving the flexural behavior of the concrete specimens. The geogrid succeeded in increasing the flexural strength of specimens tested under static loads by about 22% for Specimens GS and 81% for Specimens 2GS compared with Specimens US (Fig. 5(a)). Figure 5(b) shows the static flexural strength ratio of Specimens US, GS and 2GS. The static flexural strength ratio of Specimens US, GS and 2GS was determined by dividing the static flexural strength of Specimens US, GS and 2GS at failure load by the average static flexural strength of plain concrete. It can be seen that the static flexural strength ratio of Specimens GS and 2GS slightly improved in comparison with the static flexural strength ratio of Specimens US (Fig. 5(b)). The average static flexural strength of Specimens GS was 5% more than the average static flexural strength ratio of Specimens US. It should be mentioned that two peak loads during the static loading tests of Specimen 2GS1 were observed before failure occurred. As shown in Fig. 6, the first peak load of Specimen 2GS1 resulted from the resistance of the static load by the concrete with the geogrid reinforcement. The second peak load of Specimen 2GS1 resulted from the resistance of the static load by the geogrid layer. The second peak load increased the static flexural strength ratio of Specimen 2GS1 by about 3% more than the average flexural strength ratio of Specimens US (Fig. 6). In addition, it can be seen from Fig. 6 that Specimens GS and 2GS continued to resist the applied loads for a long time after the propagation of crack up to failure. While Specimens US suddenly failed without any clear propagation. This result matches the conclusions reported by Tang et al. (2008) and Meski and Chehab (2014).

(a)

(b)

Fig. 5. The width of crack at the tip of notch at the failure of Specimens US, GS and 2GS tested under static loads; (a) Width of crack at failure of the specimens of Group ST, and (b) Static flexural strength ratio of the specimens of Group ST.

Fig. 6. Cracking of the specimens of Group ST.

3.3. Behavior Group CY Specimens under Cyclic Loading The failure mode of fatigue life of Group CY specimens tested under cyclic loads is shown in Fig. 7(a). The fatigue life of Group CY specimens shown in Fig. 7(a) represents the accumulative number of load cycles of Specimens UC, GC and 2GC when the cracks were visible up to failure. The accumulative number of load cycles of Specimens UC, GC and 2GC was determined by multiplying the number of load cycles for each flexural stress level by the maximum cyclic load to failure load ratio, as shown in Eq. (1)