PSI - Issue 66

Ram Lal Riyar et al. / Procedia Structural Integrity 66 (2024) 181–194 Ram Lal Riyar et. al./ Structural Integrity Procedia 00 (2025) 000–000

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A bar's fracture toughness generally rises as its diameter increases because a bigger diameter results in a broader area over which stresses may be dispersed, which lowers the stress concentration at the crack tip and raises the resistance to crack propagation, and it requires more energy for crack propagation. On the other hand, a beam's fracture toughness often decreases with increasing beam size (i.e., length and depth), as shown in Figure 9. Due to the increased number of possible fracture initiation sites and stress concentration changes brought on by the bigger beam size, the material's resistance to crack propagation may be lowered. A material with greater fracture toughness will be less susceptible to unexpected failure. Consequently, a material with a bigger diameter bar will often be more resistant to fracture propagation than a material with a smaller diameter bar.

Fig. 9. Variation of Critical crack length (ac) v/s Bar diameter for small, medium and large beams at a critical point.

A bar's fracture energy normally rises as its diameter increases. This is because a larger bar has a larger cross sectional area, which allows for more absorption of energy before failing. It was also observed that a beam's fracture energy normally reduces as its size increases, as shown in Figure 10. A bigger beam has more locations where stress concentrations may happen and more possible fracture routes, allowing the crack to spread faster and with less energy. A material with greater fracture energy will need more energy to propagate a crack through it in terms of crack energy. Compared to a material with a smaller diameter bar, it will thus be more resistant to crack propagation. The lower fracture energy of a material with a smaller beam size makes it more likely for cracks to spread than a larger beam size.

Fig. 10. Plot of fracture energy (Gf) vs Bar diameter for small, medium, and large beams at critical point.

3.4. Fracture properties of reinforced concrete under corrosion The occurrence of corrosion inside a material containing a crack often leads to an increase in the effective or equivalent length of such crack. Corrosion may cause the surrounding material to degrade and weaken, which will lead the crack to prolong and expand. Chemical processes bring on corrosion at the crack's tip or inside the material around it. These interactions often result in the formation of corrosion products, such as oxides or salts, which may occupy more space than the initial material. As a result, the corrosion products put pressure on the nearby material, lengthening the initial crack and prompting it to break further. The peak load is lowered as the corrosion increases. It