Shear transfer across cracks in reinforced concrete due to aggregate interlock and to dowel action

Abstract

Synopsis Tensile cracking of reinforced concrete plate elements results in a significant reduction in the in-plane shear stiffness and strength. Shear can be transmitted across the cracks either by interlocking of the aggregate particles protruding from each face or by shearing of the reinforcement crossing the cracks. Tests of a new type are devised to study these mechanisms independently and the results are compared with several theoretical models. It is concluded that the aggregate mechanism results from a combination of crushing and overriding of the crack faces and can be predicted if the normal stiffness that restrains crack widening is known. The initial shear stiffness and ultimate shear strength due to dowel action are successfully predicted from theoretical models and an exponential curve is used to describe the intermediate behaviour.