The effectiveness of independent bent-up bars with insufficient anchorage and inclined links as shear reinforcement

Shear failure in beams is caused by diagonal cracks near the supports. Any form of effectively anchored reinforcement which intersect these cracks will be able to resist the shear stress to a certain extend. This thesis presents the results of an experimental investigation on six reinforced concrete beams in which their structural behaviour in shear was studied. All the beams were cast with the same grade of concrete and provided with identical amount of main reinforcement. In order to investigate the contribution of the independent bentup bars with insufficient anchorage and varying amount as well as the inclined links to the shear carrying capacity of the beam. Four of the beams were provided with independent bent-up bars of different amount and anchorage, and one with inclined links. The performances of the beams were measured in terms of deflection, strain, diagonal cracks loads and ultimate loads. The results show that the shear capacities of the beam with inclined links and independent bent-up bars (4T16) of 150 mm anchorage length are higher than that of the conventional designed beam. At the same time, independent bent-up bars of 9T16 with 50 mm anchorage length also give higher shear capacities due to its larger shear reinforcement to cross-sectional ratio of 1.2%. Meanwhile, independent bent-up bars of 4T16 with 50 mm anchorage length to crosssectional ratio of 0.8% give low shear capacities. It may therefore be suggested that independent bent-up bars of 150 mm anchorage length be used to replace the conventional vertical links as shear reinforcement.