PSI - Issue 64

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

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Figure 5 shows the load vs. deflection and moment vs. curvature curves at mid-span section of the beams. Furthermore, a summary of the results obtained in terms of ultimate load, ultimate concrete compression strain, maximum C-FRP plate tensile strain ε fd,exp (and its ratio compared to the ultimate C-FRP tensile strain ε fu ) and failure modes is reported in Table 2.

(a)

(b)

Figure 5. Experimental test results: (a) Load vs. mid-span displacement and (b) Moment vs. Curvature curves

Table 2. Summary of the results obtained from the flexural tests.

Beam A1

Beam A1.1

Beam A1.2

Failure load [kN]

54.0

86.8

98.0

Failure loads increase due to C-FRP strengthening [%] Concrete compressive strain at failure [mm/mm]

-

+ 61%

+ 81%

0.0050

0.0021

0.0037

C-FRP tensile strain at failure, ε fd,exp [mm/mm]

0.0096 (69% ε fu )

0.0071 (50% ε fu )

-

Debonding of both C-FRP plate and external anchorages

Failure mode

Concrete crushing

Debonding of C-FRP plate

From the obtained results, it can be observed that the control beam exhibited the typical flexural failure attributed to the yielding of the tension steel, followed by the crushing of the concrete in compression zone. As expected, beams A1.1, reinforced solely with a C-FRP plate (without external anchorage), presented higher failure loads compared to the control specimen (~ 61% higher) but exhibited a brittle failure characterized by a sudden and explosive debonding of the C-FRP plate. On the other hand, the beam reinforced with external anchorages exhibited an even higher failure load than that reinforced only with a C-FRP plate (~20% more), also demonstrating greater ductility.