PSI - Issue 42

Jamal A. Abdalla et al. / Procedia Structural Integrity 42 (2022) 1223–1230 Abdalla et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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The detailing of the U-jackets and CFRP spike anchors is shown in Fig. 2. In addition, the test matrix is shown in Table 1. The test matrix is composed of a control unstrengthened beam (BC), a U-wrapped beam (BU), and beams with anchored U-wraps (BAU). The numbers following the letters in the designation refer to the dimensions of the anchors. For example, specimen BAU 75/10/45 indicate an anchored beam with 75 mm embedment depth, 10 mm dowel diameter, and 45 º insertion angle. a

b

Fig. 2. Strengthening detailing (dimensions are in mm): (a) U-wrapped specimen (BU); (b) Anchored U-wrapped specimens (BAU)

Table 1. Test matrix

Anchor details

Specimen

U-wraps

IA ( º )

ED (mm)

DD (mm)

BC BU

-

- -

- -

- -

✓ ✓ ✓ ✓ ✓

BAU 75/10/45 BAU 50/12/90 BAU 75/12/45 BAU 50/12/45

75 50 75 50

10 12 12 12

45 90 45 45

The beams specimens were prepared by grinding the concrete 3-surfaces and cleaning it. Then, the location of the CFRP sheets and anchors were marked and the holes were drilled, cleaned, and remeasured. The hole diameter was chosen such as to provide an extra 2 mm for epoxy impregnation. Following that, the epoxy was mixed in a ratio of 2.5:1 by volume. The flexural FRP sheets were then cut (1700 mm x 150 mm), impregnated in epoxy, and bonded to the bottom of the beams. Similarly, the U-wraps were cut (550 mm x 100 mm), impregnated in epoxy, and bonded in the form of U-wraps onto the beams. The entrapped air was removed from the CFRP laminates using a grooved roller. Premanufactured anchors were impregnated with epoxy and inserted into the holes. Finally, the fan was splayed over the width of the U-wraps. The specimens were then left to cure for 7 days before testing. 2.3. Material properties The compressive strength of concrete was obtained by testing three concrete cylinders during the testing week in accordance with (ASTMC39/C39M (2015)). The average obtained compressive strength was 45 MPa. In addition, three steel coupon bars were tested under tensile tests to obtain the mechanical properties of the 16 mm diameter bars in accordance with ASTM A370-18 (ASTM International (2018)). The average yield strength and elastic modulus were found to be 590 MPa and 200 GPa, respectively. The CFRP U-wraps and anchors were fabricated from the same material (V-Wrap ™ C200H). The sheets and anchors were bonded to the concrete substrate using V-Wrap ™ 770 epoxy