PSI - Issue 54

Rami A. Hawileh et al. / Procedia Structural Integrity 54 (2024) 287–293 Hawileh et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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3.3. Strain in the FRP laminates The load versus CFRP strain for each beam specimen was plotted and presented in Fig. 4. Initially, the strains in the CFRP laminates are very small. Post cracking, CFRP laminates started to engage in taking the load. This can be noted in the load-strain plots by a change in the slope of the curve at a load of about 20 to 40 kN. The curve then ascends until failure occurs in the strengthened beam where a sudden drop or a leap takes place. In the load-strain figures below, the curve was stopped at the point where failure occurred. It is apparent that the specimen A4 presented the highest value of CFRP strain. It exhibited a maximum strain of 10900 με, very close to the rupture strain of CFRP which is 11000 με. This marks a significant improvement in utilizing the strain of FRP laminates by means of anchorage.

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Fig. 4. Strain in the FRP laminates

4. Conclusions This paper presented the experimental results of three externally strengthened RC beams with CFRP laminates, of which two beams were anchored with CFRP splay anchors. The effect of the number of anchors on the performance of the strengthened beams was studied. Specimens were tested under a four-point bending test. The behavior of the specimens in terms of load-deflection, flexural strength, strain in the CFRP laminates was studied and discussed. The following conclusions can be drawn from this study: • The use of CFRP anchors delayed the delamination and improved the behavior of the beams at failure. • Increasing the number of anchors exhibited a positive effect on controlling the brittle failure of strengthened beams and increased the utilization of FRP strength. • The strain in the CFRP laminates attached to the beam having two anchors at each end approached the ultimate rupture strain of CFRP. This marks a significant improvement in the strain utilization (99%) compared to the beam specimen with only one anchor at each end which exhibited only a 30% strain utilization. References Abdalla, J. A., Mohammed, A., & Hawileh, R. A. (2020). Flexural strengthening of reinforced concrete beams with externally bonded hybrid systems. Procedia Structural Integrity , 28 , 2312 – 2319. doi: 10.1016/j.prostr.2020.11.078 Ali, A., Abdalla, J., Hawileh, R., & Galal, K. (2014). CFRP mechanical anchorage for externally strengthened RC beams under flexure. Physics Procedia , 55 , 10 – 16. doi: 10.1016/j.phpro.2014.07.002 Al-Tamimi, A. K., Hawileh, R., Abdalla, J., & Rasheed, H. A. (2011). Effects of Ratio of CFRP Plate Length to Shear Span and End Anchorage on Flexural Behavior of SCC RC Beams. Journal of Composites for Construction , 15 (6), 908 – 919. doi: 10.1061/(asce)cc.1943 5614.0000221 Assad, M., Hawileh, R. A., & Abdalla, J. A. (2022a). Modeling the behavior of CFRP-strengthened RC slabs under fire exposure. Procedia