Browsing by Author "Akililu, Abraham"
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Item Effects of Loss of Bond on the Shear Behavior of Slender Reinforced Concrete Beams(Addis Ababa University, 2021-09) Akililu, Abraham; Esayas, Gebreyouhannes (PhD)This study investigates the shear behavior of slender reinforced concrete beams, which were fabricated with loss of bond between main longitudinal reinforcement and surrounding concrete. To remove the bond effect, the reinforcements were inserted into a plastic pipe, and then they were properly anchored behind the supports to control excessive slip. Four simply supported beams were tested under monotonic loading: one with full bond and three with the varied bond length between concrete-rebar interfaces. The test results show that the loss of bond has significant effects on crack patterns, mode of failure and ultimate load-carrying capacity. In a full span unbonded beam, only two flexural cracks were formed before failure and the mode of failure changed from shear to flexure. In partially unbonded beams, the formed failure inclined cracks are found to be steeper than the reference beam failure inclined cracks, and these cracks crossed the shear span of the beam at the end of unbonded length. Also, the failure inclined crack patterns and mode of failure are found to be similar, in partially unbonded beams. Besides, the test results show that the loss of bond has significant effects on the load-carrying capacity of beams. The ultimate load-carrying capacity has been varied depending on the percentage of unbonded length in the shear span of the beam. In the fully unbonded beam, the ultimate load-carrying capacity had increased whereas it has decreased in the case of partially unbonded beams when compared to the reference beam. However, increasing the percentage of debonding length enhanced the carrying capacity of the beams. Finally, the flexural stiffness of beams decreases as the percentage of loss of bond increases.