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. Experimental Program 2.1. Test specimen and test matrix 2.1.1 Coupon specimens

A total of fifteen different types of coupon laminates were prepared and tested in this experimental investigation to determine the mechanical properties of hybrid FRP laminates. The tested specimens included different combinations of CFRP plates and sheets, AA, and GSM. All coupon laminates were prepared according to ASTM D 638-02a (ASTM 2016) as shown in Figure 1 (a). Each coupon specimen has a width and a gauge length of 20 mm and 100 mm, respectively as shown in Figure 1(b). The thickness of the coupon varied between 4.70 mm to 5.43 mm depending on the type of laminate and number of CFRP layers, except the control (AA) specimen, it has a thickness of 2.98 mm. All composite laminate coupon samples were prepared in such a way to resemble real application when externally bonded to concrete surfaces. This was achieved by applying a layer of epoxy adhesive on a smooth surface of AA, followed by the CFRP sheet. The same procedure was followed with AA and GSM.

(b) Fig. 1. (a) Coupon specimen; (b) laminate dimensions.

(a)

2.1.2 Beam specimens A total of four RC beams were cast, three of them were strengthened with hybrid combination of AA and CFRP and AA and GSM laminates. All beam specimens have a nominal rectangular cross-section with width and height of 150 mm and 300 mm. All specimens were 2000 mm long, strengthened with 2Φ16 mm steel bars as the main longitudinal reinforcement and stirrups of Φ8 mm were provided with a spacing of 80 mm. Stirrups were provided along the beam’s span length in order to prevent shear failure as shown in Figure 2. One specimen was not strengthened and used as a control beam. The remaining beam specimens were strengthened with CFRP, and a hybrid combination of CFRP+AA and SMH+AA laminates. Figure 2 shows the beam dimensions and reinforcement details.

Fig. 2. Beam specimen details