Suppressing Delamination Failure Mode in Concrete Beams Strengthened with Short CFRP Laminates

This study is intended to examine the suppression of delamination failure for short CFRP laminates using wide transverse CFRP U-Wrap anchors. To achieve this objective, four beams were designed, fabricated, cast, and tested. Two beams serve as control specimens with different concrete strength and primary steel yield strength. The other two beams serve as strengthened specimens where they are twins of the two control beams and they both have identical flexural and anchorage strengthening reinforcement. The beams were tested in three-point bending. The control specimens (beam 1 and 2) failed in flexure. The capacity of these beams was 33 kN and 25 kN respectively. Beams 1FRP and 2FRP failed in vertical shear cracking at the laminate tip due to the shear stress concentration at 56.5 kN and 65 kN respectively. Beam 2FRP was very close to failing in flexure. It was observed that horizontal shear and diagonal shear cracking failure modes have been suppressed by the U anchors due to the intersection of fibers to these orientations. Vertical shear was the only weak plane since it was parallel to transverse fibers. Accordingly, the strengthened beams failed in that mode. To further suppress vertical shear cracking, bidirectional fabric is proposed to be used in future experiments.