PSI - Issue 64

Shamsoon Fareed et al. / Procedia Structural Integrity 64 (2024) 1057–1064 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1063

7

These strips offer notablly high resistance in restraining the development of cracks induced by high tensile stresses in the slabs, especially when compared to slabs without CFRP strips.The maximum load-carrying capacities of NAC slabs with and without CFRP strips predicted using FE analysis are shown in Table 5. As expected, the load-carrying capacities of NAC with and without CFRP strips increased with the increase in compressive strength, as the punching capacity of concrete is also proportional to the concrete compressive strength. The load-carrying capacities of slabs with CFRP showed an increase compared to the ones observed in the preceding discussions, reflecting the effectiveness of the use of CFRP in resisting punching shear.

100 120 140

100 120 140

NAC-NoCFRP-20MPa NAC-NoCFRP-30MPa NAC-NoCFRP-40MPa

0 20 40 60 80

0 20 40 60 80

NAC-CFRP-20MPa NAC-CFRP-30MPa NAC-CFRP-40MPa

Load (kN)

Load (kN)

0

0.5

1

1.5

2

0

0.5

1

1.5

2

Deflection (mm)

Deflection (mm)

(a)

(b)

Figure 6: Load-displacement relationship for slabs with different concrete compressive strengths (a) without CFRP and (b) with CFRP strips.

Table 5: Load exhibited by specimens having different strength. Concrete compressive strength (MPa) NAC without CFRP % Increasewhen compared to control (30 MPa)

Peak Load (kN)

% Increase when compared to (30 MPa)

% Increase when compared to without CFRP

NAC with CFRP

20 30 40

51.0 68.7 82.4

-26

89.2

-18

75 59 65

-

109.4 135.9

-

20

24

4. Conclusions The following conclusions can be drawn from the study: 1. The use of CFRP in strengthening RAC two-way slabs in punching was found to be effective in enhancing the overall performance of strengthened slabs. 2. A significant increase was noticed in the stiffness of slabs strengthened with CFRP strips in comparison to slabs without CFRP strips for RAC two-way slabs, resulting in higher ultimate failure loads for strengthened slabs. 3. The placement of the CFRP strips from the edge of the column was also found to be effective in reducing the deflections of the slabs at similar load levels. The placement of CFRP strips from the face of the column played a significant role in resisting the stresses induced by the punching of the column into the slab at the slab-column intersection. 4. The influence of slab thickness and concrete compressive strength was also found to be significant on the behavior of the two-way RAC slabs. 5. Deformations and load-carrying capacities exhibited by both NAC and RAC slabs were significantly influenced by thickness. Maximum deformations were observed in the 75mm thick slab at the column-slab intersection, which reduced when slab thickness was increased to 100mm and 125mm. However, load carrying capacities increased when the slab thickness was increased from 75mm to 100mm and 125mm.