10

8

6

4

2

0
0.


000


Figure 3-10.


 0.004 0.008 0.012 0.016
 Axial Strain (in/in)

Stress-strain curves for control cylinders
1 ._ .1 ... .... 1- _


able 3-3. CLlinder results
Type Grid Peak Strain at Conc. Peak Aver. COV
 dia. load peak core stress stress (%)
 (in.) (kip) load area (ksi) (ksi)
 (in/in) (in2)
 Control 1 N/A 192.33 0.00251 28.274 6.80
 Control 2 N/A 191.97 0.00232 28.274 6.78 6.83 1.1
 Control 3 N/A 195.88 0.00236 28.274 6.92
 Grid 1 5.25 184.65 0.00281 21.647 8.53
 Grid 2 5.25 146.33 0.00200 21.647 6.76
 Grid 3 5.25 178.16 0.00256 21.647 8.23
 7.67 8.5
 Grid 4 5.5 167.19 0.00279 23.221 7.20
 Grid 5 5.5 174.39 0.00256 23.221 7.51
 Grid 6 5.5 180.66 0.00279 23.221 7.78


 The carbon fibers in the CFRP grid are embedded in an epoxy matrix that creates a

smooth surface on the outside faces of the CFRP strands, which may have contributed to

spelling. A grid cylinder after testing with ruptured hoop CFRP grid strands can be seen

in Fig. 3-9(b). Experimental stress-axial strain curves for specimens Grid 1 to 3 and

specimens Grid 4 to 6 were plotted in Figs 3-11 and 3-12 respectively. The stress values

for the grid cylinders were calculated based on the area of the concrete core enclosed by

the CFRP grid and the axial strain was calculated as the average change in the length,


 -B- Control 1
 -- Control 2
 -A- Control 3





A