Experimental investigation on M50 grade concrete beams with influence of aggregate interlocking and dowel action under flexural loading

Abstract

The shear strength of the concrete beam without shear reinforcement is usually determined by shear strength of concrete compression zone, shear force due to dowel action and shear force due to aggregate interlock. The existing theories, predict shear strength of concrete beams based on geometric theories related to beam action and arch action, neglecting the influence of aggregate interlock and dowel action, as not much research information is available. The current research mainly focuses on an extensive experimental investigation on eight reinforced concrete beams with M50 grade concrete were cast and tested under flexural loading. Out of eight test specimens, four beams were provided with predetermined shear cracks having width of 5 mm, 170 mm height and inclination of 45° on either side of test specimen, whereas remaining four test specimens were not provided with predetermined shear cracks as parametric study. In eight test specimens, two beams were cast without provision of shear and flexural reinforcement and the remaining six beams were cast with increase in percentage of flexural reinforcement at 30%, 60% and 90%. Clear span of the beam was 2200 mm and cross section of the beam was 150 mm × 300 mm. The behavior of aggregate interlocking has been investigated in terms of applied load vs displacement response, stress- strain behavior, normalization curve, stiffness degradation and energy dissipation. From the test results on M50 grade reinforced concrete beam, ultimate load carrying capacity is increased with increase in percentage of flexural reinforcement for beams with predetermined shear cracks than without predetermined shear cracks. The beams with predetermined shear cracks and with additional increase in flexural reinforcement showed significant strength and stiffness.