PSI - Issue 64

Muhammad Ishfaq et al. / Procedia Structural Integrity 64 (2024) 1540–1548 Ishfaq et al./ Structural Integrity Procedia 00 (2019) 000 – 000

1544

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failure mode to rupture of the U-wraps. The fourth specimen, anchored with a 2-ply U-wraps (2U), increased the moment capacity by approximately the same 28%, albeit greater displacement was achieved. The contribution to the flexural enhancement provided by the longitudinal CFRP anchored with 2-ply U-wraps was negligible; although, the failure mode shifted from U-wrap rupture to U-wrap debonding. Overall, the addition of U-wraps permitted an increase in the strains in the longitudinal steel tension reinforcement of 21% and in the flexural CFRP of 69%, compared to the strengthened specimen 0U (Table 2).

500

750

400

600

300

450

Control (no stirrups) 0U (no stirrups) 1U (no stirrups) 2U (no stirrups) Control (#2@200) 0U (#2@200) 1U (#2@200) 2U (#2@200) Control (#4@200)

200

300

Moment (kN-m)

Shear Force (kN)

100

150

0U (#4@200) 1U (#4@200) 2U (#4@200)

0

0

0

20

40

60

80

100

Deflection (mm)

Fig. 3. Load-Deflection plots of all specimens.

Table 2. Summary of experimental results.

Failure Modes (kN) (kN-m) (kN-m) (kN-m) (µε) (µε)

Specimen

Control (no stirrups) 0U (no stirrups) 1U (no stirrups) 2U (no stirrups) Control (#2@200) 0U (#2@200) 1U (#2@200) 2U (#2@200) 0U (#4@200) 1U (#4@200) 2U (#4@200) Control (#4@200)

174.5 167.8 291.3 300.6 205.7 224.3 316.3 344.7

- - - - - - - -

- - - - - - - -

- - - - - - - -

1662 1342 2537 2612 2192 1954 2722 3215

-

Shear

1602 2868 2973 2305 3252 5064 -

Shear (U-wrap debonding) Shear (U-wrap debonding) Shear (U-wrap debonding) Shear (U-wrap debonding) Shear (U-wrap debonding) Shear (U-wrap debonding) Shear

- - - -

59.4 70.1 70.1 70.1

454.1 474.0 493.7 504.4

499.6 563.1 627.2 639.9

17167

-

Flexure

9450

7021

IC debonding U-wrap rupture

11045 11571

10175 11890

U-wrap debonding = shear force at peak load; = cracking moment; = moment at tension steel yielding; = moment at peak load; = maximum strain in tension steel at peak load; = maximum strain in longitudinal flexural CFRP at peak load