Behaviour in shear of beams with flexural cracks

Synopsis The paper aims to clarify the way in which a reinforced concrete beam with a plain web resists shear, with particular reference to the transfer of shear forces across jkxural cracks by the action known as ‘aggregate interlock’ or ‘interface shear’. Tests were made on special specimens to study the interlock phenomonen and dowel action in isolation and on ordinary rectangular reinforced concrete beams without web reinforcement. Measurements of movements at cracks in all the tests enabled the distributions of forces at cracked sections to be estimated. From the information obtained in this way, a rational equation is developed for the prediction of diagonal tension strength. The study was made using three different aggregates – a natural gravel, and two types of lightweight aggregate.