Shear transfer across a crack in concrete subjected to repeated loading. Experimental results: Part I

Abstract

This research relates to the behaviour of cracked concrete under repeated shear loading. Pre-cracked monolithic specimens were subjected to a repeated shear load. The normal restraint stiffness was applied by means of embedded reinforcing bars with a diameter of 8 mm. The variables of the tests were the concrete grade, the steel grade, the reinforcement ratio, the number of cycles, the applied shear stress level and the initial crack width. The maximum applied shear stress tm was in the range of 50%-90% of the static shear strength. The experimental program on reinforced specimens comprised 42 tests with repeated load and four tests with an increasing static shear load. The repeated tests were so-called 'high-cycle low-amplitude' experiments, i.e. the number of cycles exceeded 1,000. The displacements of the crack faces were measured by scanning the electronic signal nine times per load cycle. The load was sinusoidal. The experimental results are represented by the relations between the displacements of the crack faces and the number of cycles, the crack-opening path and the behaviour of the crack in a cycle. In the second part of the research program tests were performed on similar specimens without embedded reinforcing bars. The normal restraint stiffness was governed by four external steel bars having no bond with the concrete. The force normal to the crack face was measured by means of strain gauges glued to the steel bars.Design & ConstructionCivil Engineering and Geoscience