PSI - Issue 37

Sonia Djenad et al. / Procedia Structural Integrity 37 (2022) 321–329 Djenad et al / Structural Integrity Procedia 00 (2019) 000 – 000

326

6

60

50

40

30

Stress (Mpa)

Saadatmanesh el al 5CS3B3 Wu et al 3CS1 Unconfined: Exp Unconfined: FEM

20

10

0

0

0,002

0,004

0,006

0,008

0,01

Strain

Fig. 2. Numerical

model validation:

Stress-Strain response, FEM vs. Experimental.

a)

b)

30

30

Unconfined

5CS2 5CS1

Unconfined 3CS1 3CS2 3CS3

5cs3 5Cs4

25

25

20

20

15

15

10

10

Stress (Mpa)

Stress (Mpa)

5

5

0

0

0

0,002

0,004

0,006

0,008

0,01

0

0,002

0,004

0,006

0,008

0,01

Strain

Strain

Fig. 3. Stress-Strain response according to FRP Strips spacing: (a) 03 FRP Strips; (b) 05 FRP Strips.

Fig.3 analysis confirms that: the comparison of simulated stress-stain curves for unconfined and confined cylinders, shows clearly that concrete confined 5CS1 reaches a peak strength of 26.74 MPa, while, the predicted one for unconfined concrete is 22.69 MPa, that makes a confinement contribution in terms of resistance of 17.84%. In addition, confined 5CS4 which reaches a peak stress of 28.38 MPa allow a contribution of 25.07% in terms of compressive capacity. On the other hand, resistance of 3CS1 was increased up to 25.24 MPa with an estimated gain compared to unconfined concrete of 11.54%, whereas, with same number of strips, 3CS3 cylinders achieve a peak compressive resistance of 27.12 MPa. Predicted values demonstrate the effects of the clear spacing of FRP strips on the axial compressive behavior of partially FRP-confined concrete. It is important to notice that FRP spacing has no effect on the global behavior and the failure modes of confined members. Numerical results in Fig. 5 show that the average compressive strength of the 5CS4E4 was increased by an average of 60 %, while the capacity improvement of 5CS4E3 was around of 43.10 %. Such confrontation allows us to assess the contribution of the FRP strips stacking and layering to reduce the cracks initiation and to oppose to the radial deformations. Fig.4 analysis confirms that: confined cylinders with 5 strips of 40mm width (5CS4E4B40) present an ultimate strength of 38.14 MPa with an improvement which exceeds 176%. Results comparison shows that the FRP Strips width increases the confinement rate, which leads to a passage from softening behaviour to hardening one.