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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capacity. 2. Finite Element Modeling (FEM)

Finite Element Modeling (FEM) is an efficient approach for simulating the behavior of structural elements (Alhamaydeh, Choudhary and Assaleh, 2013; Alhamaydeh and Ghazal Aswad, 2022). This approach can study the structural performance of different types of members without the need for experimental testing (Nie et al. , 2020a; Nie, Zhang and Yu, 2021). A FE model for RC beams with Fe-SMA strengthened openings is proposed using ABAQUS software (Michael, 2009). Concrete is simulated using eight nodes element (C3D8R) with reduced integration. Steel bars and Fe-SMA reinforcement are simulated using a two-node linear displacement-based truss element (T3D2). This element is commonly used for modeling reinforcement bars with a linear material behavior. The mesh size in ABAQUS influences the finite element model’s simulation accuracy and computational efficiency. This study uses a 20 mm element mesh size to balance accuracy and computational efficiency. Fe-SMA bars are commonly used as pre-stressing tendons for repairing structures in many civil engineering applications (Izadi et al. , 2018; Cladera et al. , 2022; Raza et al. , 2022; Shahverdi et al. , 2022; Qiang et al. , 2023; Shao and Huang, 2023; Yaqub, Czaderski and Matthys, 2023). Fe-SMA bars have an elastic modulus of 133 GPa and Poisson’s ratio of 0.3 (Elkafrawy et al. , 2023). Experimental data by Shahverdi et al. (Shahverdi et al. , 2016) demonstrated complete bonding between Fe-SMA bars and concrete, a finding that has been incorporated into this numerical study to establish the bonding criteria between Fe-SMA bars and concrete. The simulation of Fe-SMA models in ABAQUS involves defining a stress-strain curve and activating a predefined field to account for pre stressing effects, as two pre-stressing levels of 0% and 50% were investigated in this study. Smeared cracking, brittle cracking, and concrete damage plasticity (CDP) models in ABAQUS represent the concrete behavior of modeled structural elements (M. Elkafrawy et al. , 2022). This study adopts the CDP model, which applies to all reinforced concrete structures, such as RC beams, representing their actual behavior (M. E. Elkafrawy et al. , 2022; Khalil et al. , 2023). Fig. 1 shows the meshed model simulated on ABAQUS. To obtain a comprehensive understanding of the constitutive models utilized for all elements within this research, readers are encouraged to consult the previous study conducted by authors [7].

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Fig. 1. Meshed model in ABAQUS (a) 2D view (b) 3D view

2.1 Specimens Detailing RC rectangular beams with a height of 450 mm, width of 200 mm, and span length of 2800 mm reinforced with longitudinal and transverse reinforcement were subjected to four-point loading. The beams have a shear span of 1000 mm. Fig. 2 shows the geometry and reinforcement details of the studied specimens. The control beam without openings noted as (Control) is a benchmark for comparing the structural behavior of beams without openings with those with openings. Three square beam openings of 100 mm, 150 mm, and 200 mm were used in each beam group of this study. These openings are left un-strengthened in Group I beams and strengthened with 2T25 Fe-SMA bars at