PSI - Issue 64

Francesco Bencardino et al. / Procedia Structural Integrity 64 (2024) 932–943 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

937

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While ϕ 6 mm steel stirrups spaced at 150 mm intervals were used as transverse reinforcement. Concerning the C-FRP plates applied on the bottom side of beams A1.1 and A1.2, they were 80 mm wide and 1.2 mm thick and were bonded over a length of 4700 mm, slightly short of the effective span of 4800 mm. The thickness of the adhesive was maintained constant at 2 mm throughout the length of all the beams. Lastly, regarding the external anchorages, they consisted of steel plates with a thickness of 2 mm, which were bonded to the concrete surface using an epoxy adhesive (same as that used to bond the C-FRP plate). The average compressive strength of the concrete at 28 days, determined by standard compression tests, was 25.8 MPa while the average yield strength of both longitudinal and transverse steel reinforcements was equal to 435 MPa. Concerning the C-FRP plates, in accordance with the data sheet provided by the manufacturer, they present a fiber volume fraction of 66%, with a longitudinal tensile strength of ~2200 MPa and a Young's modulus in tension of ~155 GPa. Furthermore, the material exhibits a strain at failure of ~1.4% and has a density of 1.45 g/cm³.

Table 1. Experimental test program.

Beam Nomenclature

Concrete cover

Steel reinforcement

Strengthening system Control: no external plate

A1

Longitudinal reinforcement: four ϕ 16 mm rebars

A1.1

One C-FRP plate with dimensions of 80×1.2×4700 mm 3

40 mm

One C-FRP plate with dimensions of 80×1.2×4700 mm 3 combined with external anchorages

Transverse reinforcement: ϕ 6 mm stirrups spaced at 150 mm

A1.2

Figure 4. Details of tested RC beams: (a) beam A1, (b) beam A1.1 and (c) beam A1.2 (dimensions in mm).