Issue 68

H. Mostafa et alii, Frattura ed Integrità Strutturale, 68 (2024) 19-44; DOI: 10.3221/IGF-ESIS.68.02

Solid 65 element. The specimens were assumed to be supported on their four sides, which accurately represented the experimental configuration. The steel reinforcement bars and GFRP gratings were modeled as two node Link 8 elements, assuming a full bond with the concrete elements. All gratings’ positions and sizes explored in the experiment were accounted for by the model meshing. In addition, the position of the top and bottom steel reinforcement layers, the vertical reinforcement, and the column stirrups were taken into account.

Figure 12: Idealization of concrete, reinforcement steel bars, and GFRP gratings for specimen SP02 (as an example)

R ESULTS AND DISCUSSION

Analysis of the experimental results Ab. 2 shows the experimental results: (1) first crack load, (2) failure load, (3) deflection at failure load, (4) concrete strain at failure, (5) steel strain at failure, (6) GFRP gratings strain at failure, and (7) toughness. Tab. 3 compares the test results to those of the control specimen SP01. Fig. 13 shows the effects of the studied variables on the load deflection curves. Fig. 14 displays the first crack and failure loads for all tested specimens, whereas Figs. 15, 16 and 17 represent the bottom reinforcement, top surface concrete, and grating strains for all specimens at failure load. Fig. 18 represents the toughness of all tested specimens, showing that the use of gratings increased toughness in all cases compared to the control specimen SP01 without gratings. Specimens with GFRP gratings exhibited a greater failure load and a wider punched failure surface compared to specimen SP01 without GFRP gratings. Fig. 19 illustrates the failure modes of all the tested specimens. T

 gf (10

-3 )

Specimen Number

P cr (kN)

P f (kN)

T kN/mm

 f (mm)

 cf (10 -3 )

 sf (10 -3 )

Top Middle Bottom

SP01

100.47

275.62

12.39

2.28

2.20

N.A.

N.A.

N.A.

1962.76

SP02

110.27

300.52

13.98

2.04

2.32

N.A.

2.78

N.A.

2212.60

SP03

110.14

327.81

13.48

2.49

2.08

N.A.

N.A.

1.88

2251.67

SP04

110.38

331.90

13.27

2.25

1.93

2.34

N.A.

N.A.

2318.58

SP05

110.08

324.74

13.32

2.32

2.23

2.00

N.A.

1.63

2157.82

SP06

111.54

351.87

13.18

2.42

2.29

N.A.

1.96

N.A.

2377.21

SP07

110.76

332.58

14.52

2.29

2.42

N.A.

2.95

N.A.

2697.67

Table 2: Experimental test results.

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