Diagonal tension resistance of structural lightweight aggregate concrete beams

Abstract

The purpose of this investigation was to determine the diagonal tension resistance of lightweight reinforced concrete beams without web reinforcement. The study was based on thirteen simple span rectangular beams. The principal variables were shear span to depth ratio a/d and percentage of tensile reinforcement p. The cross sections of all test beams were constant. The beams were tested under a two point static loading system. The external load was applied through a secondary steel beam. Al the beams failed in shear with the formation of diagonal tension cracks in the zone of combined shear and bending moment. Two types of shear failures, shear compression failure and diagonal tension failure, were observed in this investigation. Five beams with shear span to depth ratio a/d less than or equal to three failed in shear compression while the other eight beams with a/d ratio greater than three failed in diagonal tension. The ultimate loads sustained by the beams of lower a/d ratios were much higher than the initial diagonal tension cracking load. On the other hand, the ultimate load capacity of beams with larger a/d ratios was equal to the initial diagonal tension cracking load. In the latter case, the formation of the initial diagonal tension crack and collapse of the beam were simultaneous. ...