Shear Strength of Light-Weight Reinforced Concrete Beams with Continuous Rectangular Spiral Reinforcement

Concrete beams reinforced with rectangular spiral shear reinforcement instead of the ordinarily closed stirrups have been recently extended. However, this extension has never been addressed for light-weight concrete structural elements. An experimental program is conducted in this research to investigate the shear performance of light-weight concrete beams that are transversely reinforced with continuous rectangular spirals. Four groups, including 20 specimens, were constructed where the groups contain two different shear span to depth ratios of 2.0 and 1.5 and have two different spiral spacing of 200 mm and 150 mm. Five different inclination angles of the spiral reinforcement were considered for each group: 85°, 80°, 77.2°, 75o, and 72.5°. The beams were tested under static four-point loading. Test results have shown that using rectangular spiral reinforcement has enhanced the shear capacity and deflection of the test specimens. Shear strength enhancement has ranged from 3% up to 47% compared to the ordinarily closed stirrups. Test results have also shown that the angle of inclination, which would result in the best performance, is influenced by the shear span to depth ratio. The optimum angles were found 85° and 75°, for the shear span to depth ratio of 2.0 and 1.5, respectively.