PSI - Issue 64

Mohamed Elkafrawy et al. / Procedia Structural Integrity 64 (2024) 436–444 Author name / Structural Integrity Procedia 00 (2019) 000–000

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index. Increasing the opening size to 150 mm decreases the ductility index to 2.55. The ductility index decreases to 2.09 when the beam opening size increases to 200 mm. Adding Fe-SMA bars as reinforcement around the opening increases the beam’s ductility. The larger the opening size, the more the ductility increases when adding Fe-SMA bars. The ductility increases by around 89% from 2.09 to 3.95 when the 200 mm opening is reinforced with Fe-SMA bars. Reinforcing the 100 mm and 150 mm openings with Fe-SMA bars increased the ductility index by 5% and 20%, respectively. Pre-stressing the Fe-SMA bars to 50% further increases the beam's ductility index, primarily due to the enhancement in initial stiffness rather than an increase in peak load displacement. As seen, reinforcing the 100 mm, 150 mm, and 200 mm openings with 50% pre-stressed Fe-SMA bars increases the ductility index from 2.88, 2.54, and 2.09 to 3.12, 3.13, and 4.37, respectively.

Fig. 7. Ductility index of each beam

5. Conclusions Openings within RC beams significantly compromise their structural performance and integrity. Strengthening openings with Fe-SMA bars enhances the load-carrying capacity as well as the ductility of RC beams. The behavior of RC beams with various opening sizes strengthened with Fe-SMA at varying pre-stressing levels has been studied, and the following conclusions were made: • The stress localization and crack development around openings in RC beams increase with the increase in opening size. However, using a large Fe-SMA reinforcement diameter has been found to reduce the development of diagonal cracks around openings at ultimate load conditions. • RC beams strengthened with Fe-SMA reinforcement around openings experienced higher strength and ductility than those not reinforced around openings. With the addition of Fe-SMA reinforcement, the ultimate load capacity increased by 27% for beams with 100 mm openings size, 37.5% for beams with 150 mm openings size, and 50.1% for beams with 200 mm openings size compared to when unreinforced. • The degree of pre-stressing applied to Fe-SMA bars around the opening has a minor influence on the structural performance of RC beams with openings. By increasing the level of pre-stressing up to 50%, the ductility increased marginally by 3.14% for beams with 100 mm openings size, 1.7% for beams with 150 mm openings size, and 9.6% for beams with 200 mm openings size compared to when non prestressed. Acknowledgments The authors gratefully acknowledge the financial support provided by the American University of Sharjah (AUS). References Ahmed, A. et al. (2012) ‘Reinforced concrete beams with web openings: A state of the art review’, Materials and