PSI - Issue 17

Waleed H. Alhazmi et al. / Procedia Structural Integrity 17 (2019) 292–299 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

298

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changed from bearing to tension with decreasing w/d H with constant e /d H . As mentioned before, shear-out failure can be regarded as a special case of bearing failure, therefore, the joint strength,  ult , may be determined by the following equation (Park 2001):  ult P d t ult B = (6) where t is the plate thickness, t = 1.2 mm. Table 3 shows the stiffness and the strength of the joint as a function of w/d H , e /d H , d B /d H , and d B . It is clear that, the main parameter control the strength of the joint is the contact arc, i.e. d B . The highest value of the joint ultimate load is equal to 3.41 kN and equals only 2.7% of the ultimate load of open-holed specimen.

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Test # d H d B e w 1 7 6 10 20 2 10 6 11 30 3 10 6 25 30 4 10 6 25 50 5 13 6 17 50 6 13 6 25 50 7 10 8 30 30 8 10 8 30 50 9 13 8 25 50

2

Load, kN

0

0

2

4

6

Bolt displacement, mm

Fig. (3) Load-Bolt Displacement curves of Unidirectional CFRP plates. Table (3) Single-Bolt Tension Joint Test Results for Unidirectional CFRP Plates

e /d H

Test #

w/d H

d B /d H

d B , mm

Disp. @ P ult , mm

P ult , kN * 2.45 2.35 2.58 2.74 2.15 2.62 3.23 2.94 3.41

Stiffness

 ult , MPa

1 2 3 4 5 6 7 8 9

2.86

1.43

0.86

6 6 6 6 6 6 8 8 8

1.2 1.1 1.1 1.5 0.9 1.1 1.6 1.1

2.04 2.14 2.35 1.83 2.39 2.38 2.02 2.67 2.66

340.28 326.67 358.33 381.11 298.61 363.89 336.88 306.25 355.20

3 3 5

1.1 2.5 2.5

0.6 0.6 0.6

3.85 3.85

1.31 1.92

0.46 0.46

3 5

3 3

0.8 0.8

3.85

1.92

0.61

1.28

* It is worth noting that, P ult in open-holed specimen, d H /w = 0.3, is equal to 126 kN. The present results showed the behaviour of unidirectional CFRP plates containing either open or pin loaded circular holes with no clamping force. The effect of clamping force and washer size on the strength and mode of failure of mechanically fastened joints in unidirectional CFRP is left to future interest. The clamping force may be increased the ultimate strength of the joint markedly as a result of the change in the mode of failure. Therefore, it can be recommended that, the concrete cover replacement technique and/or clamped plate end anchorage technique are the suitable techniques for fixing unidirectional composite without introducing high stress concentration sites.