Issue 61

R. Elsadany et alii, Frattura ed Integrità Strutturale, 61 (2022) 294-307; DOI: 10.3221/IGF-ESIS.61.20

summarized in table 7. In general, the first crack load and ultimate load of all RC beams containing RCA are lower than those of corresponding RC beams without RCA. The opposite trend was observed for maximum deflection.

Comp. St rength (7 days) Comp. St rength (28 days) Tensile St rength (28 days)

100 150 200 250 300 350 400 450

401.7

348.2

Strength (N/mm 2 )

242.7

173.7

74.33

52

0 50

Normal C.Agg.

Recycled C.Agg.

Figure 4: Compressive and tensile strength of concrete with and without RCA.

Ultimate Load, P ULT , (kN)

P ULT - RCA /P ULT - NCA For beams failed due to concrete crushing

Maximum Deflection (mm)

Beam First crack Load (kN)

Failure mode

BNG1 BRG1

15 12

57 54

27 35

Rupture in FRP Concrete crushing

N/A

Yielding in steel followed by Concrete Crushing Yielding in steel followed by Concrete crushing

BNS1

18.5

70

22

0.90

BRS1

15

63

25

BNG2 BRG2

21 17

70 62

25 32

Concrete crushing Concrete crushing

0.89

Yielding in steel followed by Concrete crushing Yielding in steel followed by Concrete crushing

BNS2

28

79

18

0.99

BRS2

24

78

22

BNG3 BRG3

31 25

79 72

23 31

Concrete crushing Concrete crushing

0.91

Yielding in steel followed by Concrete crushing Yielding in steel followed by Concrete crushing

BNS3

39

89

17

0.96

BRS3

28

85

19

Table 7: Flexural test results of all RC beams

In the beginning, a comparison between the measured values of ultimate loads of GFRP RC beams and those predicted by the ACI 440.1R-06 provision [17] was made. The approach of the ACI code was based on the forces equilibrium, strain compatibility of sections and considers the equivalent stress block. The equations of moment capacity depend on whether the reinforcement ratio is lesser or higher than the balanced ratio:

300