PSI - Issue 28

Jamal A. Abdalla et al. / Procedia Structural Integrity 28 (2020) 2312–2319 Author name / Structural Integrity Procedia 00 (2019) 000–000

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2.2. Materials Concrete : Three concrete cylinders were tested after 28 days of curing and their average compressive strength was 47.2 MPa. Steel bars: Three steel bar specimens were tested at room temperature using a universal testing machine and their average yield strength, ultimate strength and modulus of elasticity were 551 MPa, 640 MPa and 200 GPa, respectively. Aluminum Allo y Plates : The type of AA plates used is AA5083-H111 (Aalco 2017). This type of AA plates has a high tensile strength. The mechanical properties of AA5083-H111 are shown in Table 1. CFRP materials: The CFRP plates used in this study has a thickness of 1.4 mm, modulus of elasticity of 170 GPa and ultimate tensile strength of 3100 MPa based on the manufacturer technical worksheet sheet (MAPEI 2017). GSM materials : Galvanized steel mesh (GSM) with high tensile strength, which is composed of high carbon steel cords with a micro-fine zinc galvanized coating, was used. The high tensile strength GSM sheets have a high cord density of 7.09 cord/cm (Hawileh et al., 2018). Epoxy adhesive: GeoLite® Gel (MAPEI 2017) was the epoxy used for bonding the FRP sheets to the RC beams and that has a modulus of elasticity of 5.3 GPa based on the manufacturer technical worksheet (MAPEI 2017). Table 1 shows the mechanical properties of Steel bars, AA 5083-H111, GSM, CFRP and Epoxy.

Table 1. Mechanical properties of materials

Material

Ultimate strain (%)

Ultimate tensile Strength (MPa)

Yield Strength (MPa)

Modulus of Elasticity (GPa)

Steel bars

640 310

551

200 70.3 190

20 25

Aluminum 5083-H111

148.8

GSM CFRP

3070 3900

- - -

1.6 1.7

70-250

Epoxy (GeoLite® Gel)

4.0

5.3

-

2.3. Specimen preparation and test setup Fifteen coupon specimens were tested using a Universal Testing Machine (UTM) with a 100 kN capacity as shown in Figure 3 (a). Four RC beam specimens were strengthened with hybrid materials of one-layer GSM of high density cord SMH and CFRP attached to the RC beam’s soffit then AA plate were bonded to the beam using epoxy adhesive. All four beams were loaded and tested in four-point bending using A Universal Testing Machine (UTM) that has a capacity of 2000 kN as shown in Figure 3(b). The load was applied at a rate of 2 mm/min and a linear variable differential transducer (LVDT) was used to record the mid-span deflection. Load-deflections readings were continuously recorded and cracks were marked and traced during testing as shown in Figure 3 (b).

(a) (b) Fig. 3. Test setup; (a) tensile test of coupon specimen; (b) four-point bending test of beam specimen.

3. Results and Discussions 3.1 Coupon specimens

Table 2 shows a summary of the average values of ultimate loads, average values of strain at ultimate load, average of maximum extensions and failure modes. It is observed from Table 2 that the ratio of strain at ultimate