WEB REINFORCEMENT EFFECTS ON SHEAR CAPACITY OF REINFORCED HIGH-STRENGTH CONCRETE BEAMS

Thirty-two beams made of normal- and high-strength concrete were teste d to study the effects of web reinforcement placement on load-carrying capacity. Sixteen beams had stirrup reinforcement only in the shear s pan (type A beams); the other 16 had web reinforcement only in the fle xural span (type B beams). The shear span-to-depth ratio a/d was varie d between 0.6 and 3.7; the concrete strength was varied between 31.7 a nd 93.1 MPa. Test results indicate that for a/d = 2, high-strength con crete beams have more reserve capacity than normal-strength concrete b eams. For beams with web reinforcement in the shear span only, the she ar reinforcement is more effective for smaller aid ratios. The ultimat e load capacity of the two types of beam is comparable for aid < 2. Fo r higher aid ratios, the ultimate load capacity of type A beams is sup erior to that of type B beams. The ductility of the two types of beam is comparable for a/d = 0.6, but with increasing a/d the ductility of type A beams becomes superior to that of type B beams. Also, a compari son was carried out with ACI, BS 8110 and CEB-FIP, and it is suggested that some of their recommendations be reconsidered.