Improved Shear Performance of Bent-Up Bars in Reinforced Concrete Beams

Shear failure of reinforced concrete beams is often sudden and catastrophic. This sudden failure, due to shear, made it necessary to explore more effective ways to design reinforced concrete beam for shear. The reinforced concrete beams show different behavior at the failure stage in shear compare to the bending, which is considered to be unsafe mode of failure. The shear cracks progressive rapidly without sufficient advanced warning, and the diagonal cracks that develop due to excess shear forces are considerably wider than the flexural cracks. The cost and safety of shear reinforcement in reinforced concrete beams led to the study of other alternatives. Bent-up bars have been used in the past. New form of bent-up bars will be used. Cross bars will be welded to these bent-up bars making rectangles capable of resisting shear in a plane compared to single bar performance. The main purpose is to identify the most efficient shape to carry shear forces at the lowest cost. Several reinforced concrete beams were carefully prepared and tested in the lab. The results of these tests will be presented and discussed. The deflection of each beam is also measure at a given applied load. The propagation of shear cracks was also closely monitored.