Influence of stirrup spacing on shear resistance of reinforced concrete beams

This study investigates the behaviour of, and evaluates the benefit accruing to, shear critical reinforced concrete beams, when provided with vertical stirrups spaced at decreasing intervals along the axis of the beam, but with the same amount of web reinforcement per unit beam length. Tests are carried out on three reinforced concrete beams, identical in geometry, flexural reinforcing, amount of web reinforcement per unit span length, material properties and test details. The only varable is vertical stirrup leg spacing along the span. The beams are loaded at half point on a simple span of 2500 mm and all fail in shear. Experimental results demonstrate that, as stirrup spacing decreases, there is a strength gain at ultimate. Besides increased carrying capacity, closer spacing of shear reinforcement results in more beneficial deformational characteristics. Transverse deflections and crack widths decrease as stirrup spacing decreases. The test results establish the desirability of using stirrup reinforceme...