PSI - Issue 37

Ghusoon S. Alshami et al. / Procedia Structural Integrity 37 (2022) 367–374 Alshami et al./ Structural Integrity Procedia 00 (2021) 000 – 000

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Fig.8. Ultimate attained strain in the CFRP laminates

Fig.9. Failure of tested prisms: (a) CC; (b) SD; (c) SD+AR; (d) SD+AR; (e)SD; (f) SR+AP.

Table 4 shows an increase in the ultimate load-carrying capacity ( P u ) of the strengthened specimens over that of the control unstrengthened specimen (C) in the range of 66 – 121%. Also, the results show that anchoring the laminates with FRP anchors enhanced the behavior of strengthened specimens and their ultimate load-carrying capacity by 11 33% compared to L1(unanchored prism). Ductility and strain in the FRP laminates were also improved. The test results also indicate that there is a direct relation between the anchor embedment depth and the flexural capacity of the specimens, where increasing the embedment depth increased the pullout capacity. Therefore, FRP debonding failure was delayed, capacity of the prism was increased, and strain in the CFRP laminates was utilized as shown in Figs. 6-8. The failure mode of the control specimen C (plain concrete), and L1 (strengthened and unanchored prism) was concrete crushing and CFRP sheet debonding, respectively. Prisms with embedment depths of 50 and 75 mm faced the same failure mode, which was anchor rupture along with sheet debonding. This shows that short, embedded anchors are insufficient for transferring all the load, since they resulted in anchor rupture before the laminate. On the other hand, longer dowels with embedment depths of 100 mm and 125 mm developed more strains in the CFRP laminate until rupture, where such specimens failed by sheet debonding (SD) and sheet rupture with anchor pullout (SR+AP), respectively. So, they were able to transfer the load better than short, embedded anchors. 5. Summary & Conclusion This paper investigates the flexural strengthening of concrete prisms using CFRP laminates and CFRP anchors. Four point bending tests were performed on all prisms and the midspan load-deflection response curves are ploted. Based on the experimental results, it could be concluded that: • Strengthening concrete prisms showed a significant increase in its capacity in the range of 66-121%. • Using CFRP spike anchors is an effective technique to increase the capacity and ductility of the strengthened systems by delaying FRP debonding.