Issue 56

K. Fawzy et al, Frattura ed Integrità Strutturale, 56 (2021) 123-136; DOI: 10.3221/IGF-ESIS.56.10

Material properties CFRP : The fibre used in the experimental work is longitudinal, unidirectional wrap of Carbon Fibre (Fig. 2). Tab. 3 displays the main features of the manufactured CFRP strengthening material used for the tests. Epoxy adhesive : The epoxy adhesive consists of two-part; resin (component A) and hardener (component B). Tab. 3 shows a summary of the mechanical and physical characteristics of CFRP impregnation resin used. Concrete and steel : To achieve concrete mix constituents with a strength of 32 N/mm 2 , the concrete mixture was designed using the ACI method. For each casting process, three standard concrete cubes (150 mm x 150 mm x 150 mm) and three standard concrete cylinders (150 mm x 300 mm) were cast and cured in water for 28 days. The average of compressive strength after 28 days was 32 MPa (Tab. 1). Standard tension tests were performed on steel specimens according to ASTM using MTS 200 tons universal testing machine. Three steel specimens were tested for each bar diameter and the average value was considered. the average steel yield stress was 525 MPa for the longitudinal reinforcement and 400 MPa for the stirrups (Tab. 2).

Properties

Values found in the laboratory

Compressive strength (MPa) Modulus of elasticity (GPa) Modulus of rupture (MPa)

32

30.6

3.4

Table 1: Concrete properties.

Reinforcement type Tension (10 mm) Compression (8mm)

Yield strength (MPa)

Modulus of elasticity (GPa)

525 525 400

200 200 195

Shear (6 mm)

Table 2: Steel properties.

Materials

Properties

Values (GPa)

Modulus of elasticity (GPa) Elongation at ultimate (%) Design thickness (mm/ply) Tensile strength (MPa)

230 1.70

0.129 4000

CFRP laminates

Density (g/cm 3 )

1.82 4.50

Modulus of elasticity (GPa) Elongation at ultimate (%) Tensile strength (MPa) 0.90 30 Table 3: CFRP laminates and epoxy adhesive properties.

Epoxy (the mix)

Figure 2: CFRP sheet used in this study.

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