Issue 63

M. Khalaf et alii, Frattura ed Integrità Strutturale, 63 (2023) 206-233; DOI: 10.3221/IGF-ESIS.63.17

Figure 3: RC beam models dimensions, reinforcements, loading arrangement and the strengthening technique details

Figure 4: Types of the used finite elements [26].

Concrete The considered concrete properties and failure criteria for all beams models in the current research such as the elastic modulus of concrete E c , Poisson’s ratio  c , ultimate compressive strength f c , ultimate tensile strength which is typically ranges from 8% to 15% of the compressive strength [27] and is considered as f t ≈ 0.1f c . The multi-linear isotropic simplified compressive uniaxial stress-strain curve characteristics are tabulated in Tab. 1. Concrete is considered as a quasi-brittle material where the stress decreases gradually after the peak stress and the properties of concrete in compression and tension are different from each other. The shear transfer coefficients β t and β c are for open and closed cracks respectively. They denote the reduction factors of the concrete shear strength for the subsequent loads inducing the shear sliding across the crack face [26]. These

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